US20010055286A1 - Asymmetric internet access over fixed wireless access - Google Patents

Abstract

A radio base station in a Fixed Wireless Access System broadcasts downlink data packets, each packet being transmitted on a single logical channel. A plurality of network subscribers in a sector may be members of a user group, each user group configured to receive and transmit packets transferred on a specific single logical channel only. Packets include a destination address which specifies a member of the user group. The packets include a token which specifies which user group member may transmit uplink data to the base station on the next frame. Logical channels are yielded for use by circuit switched traffic when required.

Description

FIELD OF THE INVENTION
• The present invention relates to telecommunications networks and particularly, although not exclusively, to communicating packet data in Fixed Wireless Access (FWA) networks.[0001]
BACKGROUND TO THE INVENTION
• In a fixed wireless access (FWA) telecommunications system, subscribers are connected to a backbone telecommunications network by means of radio links in place of traditional copper wires. Each of a plurality of subscribers is provided with a subscriber radio terminal. A plurality of subscriber radio terminals of a plurality of subscribers premises communicate with a base station which provides cellular coverage, typically in urban environments over a 5 km radius. Each base station may be connected to a Public Switched Telecommunications Network (PSTN) switch via a conventional transmission link, known as a backhaul link. A number of potential subscribers sites in a base stations' area of transmission can be of the order of several thousands. A single base station can serve up to several thousand subscribers, making the installation and maintenance cost of a fixed wireless access system lower than that of an equivalent copper wire access network.[0002]
• Referring to FIG. 1 herein, there is illustrated a prior art fixed wireless access system. A plurality of[0003]subscriber radio terminals100 each comprising atransceiver101 and an antenna102, part of a residential subscriber system (RSS) installed at a subscriber's premises, communicate with aradio base station103 having abase station antenna104 and a basestation transceiver apparatus105. A plurality of suchradio base stations103 each communicate with acentral office switch106 to gain access to abackbone telecommunications network111, eg a Public Switched Telephone Network (PSTN) or an Integrated Services Digital Network (ISDN). In a geographical area, eachbase station103 is connected to alocal exchange switch106 via abackhaul transmission line107 which may comprise for example a terrestrial line eg fiber optic cable or coaxial cable, or a microwave transmission link. Communication between the subscriber radio terminal and the base station is via awireless radio link108. Each localwireless link108 betweenradio base station103 andsubscriber radio terminal100 comprises an uplink beam from the subscriber transceiver and antenna to the radio base station, and a downlink beam transmitting from the radio base station antenna and transceiver to the subscriber antenna and transceiver. Equal spectrum of frequency slots are allocated for uplink and downlink according to a frequency division duplex scheme, in which a first frequency of a frequency pair is allocated for uplink transmission and a second frequency of the frequency pair is allocated for downlink transmission.
• Conventional fixed wireless access systems are narrow band systems which are mainly designed for providing narrow band circuit switched telecommunications services such as telephony, fax or modem. On the other hand, with increased penetration of personal computers into domestic residential markets, access to Internet services is increasingly demanded by subscribers. Thus, it is desirable for subscribers to a FWA system to be able to connect their Personal Computers (PCs)[0004]109 to their RSSs for accessing the Internet rather than require a conventional wire based communications network line to be installed at their premises. The most popular Internet services include world wide web services and downloading of files. In particular, subscribers are increasingly making use of Internet services downloaded from Internet service providers. Internet access traffic is characterized as being highly asymmetric in the transfer of data as between a subscriber and an Internet service provider. This results in a significant difference in data rate in one direction on a subscriber line compared with another, appropriate direction. Internet access also has the characteristic of having a relatively long holding time. For example, a World Wide Web (WWW) session may last for a few hours.
• For example, a dominant Internet access traffic type in the residential subscriber market is generated by web browsing. Typical figures on an average download on a page of data by a subscriber is around 50 kBytes, and some estimates project an increase of this figure to around 150 kBytes by the year 2000. Assuming subscribers will tolerate a 6 second waiting time during the page download, a peak data rate for download of web browsing data over a fixed wireless access link is of the order of 64 kbits/s increasing to around 192 kbits/s by the year 2000. After page download, subscribers typically take time to study the information downloaded. Estimates of an average time for such study is around 24 seconds, giving an average data rate on a fixed wireless access downlink of around 13 kbits/s, estimated to increase to around 39 kbits/s by the year 2000.[0005]
• However, on an uplink, data sent from a subscriber to an Internet service provider is typically very light compared to the data downloaded from the Internet service provider. An approximate estimate of uplink loading requirement is that the uplink loading is typically around one tenth of the downlink loading for Internet services, ie one subscriber will produce a peak uplink rate of around 6.4 kbits/s (increasing to 19.2 kbits/s by the year 2000) and an average data rate of 1.3 kbits/s (increasing to 3.9 kbits/s by the year 2000).[0006]
• Whilst conventional fixed access wireless systems may be efficient for services, eg voice data, having a relatively balanced data rate in each direction, maintaining a circuit switched connection over a fixed wireless access link for services having an asymmetry of data rate as between different directions of a subscriber link is inefficient use of available wireless link bandwidth.[0007]
• FIG. 2 of the accompanying drawings schematically illustrates a prior art uplink transmission from RSS antenna[0008]102 toradio base station103. Theuplink transmission201 comprises a sequence of timeslots, each lasting approximately 300 microseconds. Afirst timeslot202 oftransmission201 comprises an uplink transmission from subscriber to the base station. Timeslot203, immediately followingtimeslot202, would usually represent a pause in the transmission by the the subscriber whilst the base station receives data transmitted intimeslot202. Timeslot204, which immediately followstimeslot203, usually represents a gap when the RSS is still unable to make a downlink transmission to the subscriber RSS. Timeslot205, which immediately followstimeslot204, represents a second timeslot when the radio base station is able to make a downlink transmission to the subscriber RSS. Thus, each downlink transmission timeslot is separated by two intermediate timeslots.
• [0009]Gap timeslot204 represents a delay when the RSS may change the carrier frequency which it uses to transmit to the base station. Other procedures may also be executed by the RSS duringtimeslot204 and other subscriber terminals may communicate with the base station. The gap may also exist in order to allow a transmit timeslot205 (immediately following timeslot204) to be time aligned with other transmissions, ie to attempt to ensure that all transmissions to the radio base station arrive at the same time.
• In addition to data transfer relating to internet services being asymmetric, ie, considerably more data being transmitted on the downlink than on the uplink as discussed herein above, the data transferred can be of a bursty nature, thus the data is transmitted intermittently, compared with, for example, voice data which tends to be continuous. The continuous nature of circa switch data, such as voice, means that it is undesirable for the RSS to change the carrier frequency which results in gaps, such as[0010]timeslots204. However, for package switch data, the constraints of maintaining continuous data transfer is not present, therefore, it is more acceptable for the RSS to change carrier frequency more frequently, because the bursty nature of the data transferred allows a training sequence to take place during the gaps in data transfer.
• In general, each subscriber RSS will experience different propagation characteristics over its uplink/downlink air interface. The radio base station transmits on the downlink over a plurality of downlink frequencies. Each downlink frequency is divided into a plurality of timeslots. It may not be possible for each subscriber RSS to communicate on all of the downlink frequencies offered by the radio base station. Individual subscriber RSSs may be restricted to a selection of a few of the downlink frequencies available. As bearer timeslots on preferred downlink frequencies become occupied by communications, it is inefficient to place an existing circuit switched connection onto a different bearer timeslot on a different carrier frequency. The reason for this inefficiency is that every time a circuit switched connection is moved from one to bearer timeslot to another bearer timeslot, there is a relatively long training sequence required for transfer of that circuit switched connection between different bearer timeslots. Thus, consecutive bearer timeslots carrying a circuit switched connection must be at least two intermediate timeslots apart to allow transfer of a circuit switched connection from one bearer timeslot to another bearer timeslot. For example, a circuit switched connection on a frequency division duplex pair may carry a first 500 μs timeslot for transmit on the uplink, and then receive a second 500 μs timeslot on the downlink, before proceeding to transmit a third 500 μs timeslot on the uplink followed by a fourth 500 μs timeslot on the downlink, and so on throughout the duration of a circuit switched connection. For a change of carrier frequency, there must be an interruption in communication, since changing the circuit switch connection from one frequency to another takes longer than 1000 μs, meaning that a transmit timeslot or a received timeslot must be omitted in the communication. Since data carried on circuit switch connections, eg voice data is more susceptible to interruptions than packet switched data, to avoid degradation of grade of service, it is more efficient once the circuit switched connection is set up, to retain that circuit switched connection on a same bearer timeslot on a same carrier frequency. However, packet switched data may tolerate higher levels of delay, due to the bursty nature of data transfer and also since the packet switched data may be completely retransmitted if necessary, it is not as delay sensitive as circuit switched traffic (eg voice data) in general.[0011]
SUMMARY OF THE INVENTION
• An object of the present invention is to provide efficient packet switched data transfer for subscribers to a FWA network. This may be achieved by taking advantage of the asymmetric and bursty nature of data transfer resulting from use of services such as internet access.[0012]
• A further object of the present invention is to provide a bandwidth on demand data packet transfer system over a FWA network.[0013]
• Preferably, a group of users in a cell transmitted to by a radio base station share a common logical channel on a frame by frame basis which can be yielded to circuit switched traffic when there are few or no more spare air side logical channels available for the circuit switched data. Logical channel sharing is preferably provided in the form of closed user groups wherein each user of the user group is required to register and join the group before using the shared logical channel. Preferably, a user group forms a virtual pipe over an air interface and data packet at both ends of the air interface may be dynamically routed or switched along a number of parallel user groups. Preferably, the system can be added to an existing known air interface protocol. The system may take advantage of a broadcast nature of downlink transmissions from a radio base station so that several subscribers belonging to a closed user group may listen to the same logical channel and, using a token mechanism, a user who may make an uplink transmission on a next frame may be decided.[0014]
• According to one aspect of the present invention there is provided a communications apparatus for transferring packet switched data said apparatus comprising:[0015]
• a radio base station capable of transmitting downlink data packets each said data packet being transferred in a specified single timeslot replicating over a plurality of time frames; and[0016]
• at least one network subscriber equipment capable of receiving said downlink data packets;[0017]
• wherein said subscriber equipments are joined as members of at least one user group, each said user group configured to receive said downlink packets in said specified single repeating timeslot only.[0018]
• According to a second aspect of the present invention there is provided a method of communicating packet switched data comprising the steps of:[0019]
• communicating a downlink data packet from a radio base station to at least one network subscriber equipment,[0020]
• wherein said network subscriber equipment is registered as a member of a user group, said user group configured to receive said downlink packets in a specific single timeslot only.[0021]
• According to a third aspect of the present invention there is provided a method of communicating packet switched data over a wireless link, said method comprising the steps:[0022]
• registering at least one subscriber lines for receipt of said packet switched data on a downlink channel of said wireless link; and[0023]
• communicating said packet switched data on said downlink channel;[0024]
• wherein said downlink packet switched data carries an address of a group of registered said subscriber lines, for which said data is intended.[0025]
• According to a fourth aspect of the present invention there is provided a method of communicating packet switched data over a wireless link, said method comprising the steps of:[0026]
• registering at least one subscriber line for receipt of said packet switched data on a downlink channel of said wireless link;[0027]
• allocating a single uplink channel of said wireless link for receipt of packet switched data from a group of said subscriber lines;[0028]
• transmitting a token data on said downlink, said token data indicating which of said registered subscriber lines has authorization to transmit on said uplink channel.[0029]
• According to a fifth aspect of the present invention there is provided a method of communicating packet switched data over a wireless link, said method comprising the steps of:[0030]
• receiving packet switched data on a downlink channel of said wireless link, said downlink channel allocated for receipt by a group of subscriber lines;[0031]
• receiving a token data indicating authorization to transmit packet switched data on an allocated uplink channel; and[0032]
• transmitting said packet switched data on said allocated uplink channel.[0033]
• According to a sixth aspect of the present invention there is provided a method of registering a plurality of users of a communications network for receipt of packet switched data services over a wireless link, said method comprising the steps of:[0034]
• receiving a registration request from a said network user;[0035]
• in response to said registration request, allocating a user identification data to said user;[0036]
• allocating an identification data to said user; and[0037]
• allocating at least one logical communications channel to said user.[0038]
• According to a seventh aspect of the present invention there is provided in a communications network operating a wireless link for communicating packet switched data to a network user of at least one channel of a plurality of channels, a method of re-synchronizing a user with a said channel to which said user has been previously assigned, said method comprising the steps of:[0039]
• determining if said user is already assigned to a said logical channel;[0040]
• if said user is already assigned to said logical channel, retrieving data identifying[0041]
• a user group to which said user belongs;[0042]
• a logical channel to which said group is assigned;[0043]
• a physical channel to which said group is assigned; and[0044]
• transmitting said data identifying said user group, said logical channel and said physical channel over said wireless link.[0045]
BRIEF DESCRIPTION OF THE DRAWINGS
• For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:[0046]
• FIG. 3 illustrates schematically a radio base station providing air interface coverage for A cell, the cell comprising subscribers forming a user group;[0047]
• FIG. 4 illustrates data which may be associated with the user group illustrated in FIG. 3;[0048]
• FIG. 5 illustrates schematically components of a radio base station, a user's Internet terminal and a residential subscriber system connected to a first Internet service provider over a telecommunications network and a second Internet service provider connected by a digital leased line;[0049]
• FIG. 6 illustrates schematically protocol stacks intended for transferring data between the components of FIG. 5 when the telecommunication network comprises a PSTN;[0050]
• FIG. 7 illustrates schematically protocol stacks intended for transferring data between the components of FIG. 5 when the telecommunication network comprises a ISDN;[0051]
• FIG. 8 illustrates schematically protocol stacks intended for transferring data between the components of FIG. 5 when the Internet service provider is connected by means of the digital leased line;[0052]
• FIG. 9 illustrates a format of a downlink packet data unit used by the preferred embodiment's Media Access Control (MAC) layer protocols shown in FIGS.[0053]6 to8;
• FIG. 10 illustrates a format of an uplink packet data unit used by the preferred embodiment's MAC layer protocols shown in FIGS.[0054]6 to8;
• FIG. 11 illustrates functional components of the preferred embodiment's MAC layer;[0055]
• FIG. 12 illustrates steps typically executed by the functional components illustrated in FIG. 11, including a user registration step, a user joins group step, a suspend and resume transmission step, a physical channel switch step, and a group re-synchronization step;[0056]
• FIG. 13 details steps executed during the user registration step of FIG. 12;[0057]
• FIG. 14 details steps executing during the user joins group step of FIG. 12;[0058]
• FIG. 15 details steps executed during the suspend and resume transmission step of FIG. 12;[0059]
• FIG. 16 details steps executing during the physical channel switch step of FIG. 12; and[0060]
• FIG. 17 details steps executed during the group re-synchronization step of FIG. 12.[0061]
DETAILED DESCRIPTION OF THE BEST MODE FOR CARRYING OUT THE INVENTION
• There will now be described by way of example the best mode contemplated by the inventors for carrying out the invention. In the following description numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one skilled in the art, that the present invention may be practiced without using these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention.[0062]
• FIG. 3 of the accompanying drawings illustrates schematically part of a Fixed Wireless Access (FWA) telecommunications network in accordance with the preferred embodiment. A Radio Base Station (RBS)[0063]301 provides cellular coverage, typically in urban environments over a 4 kilometer radius, to a plurality of subscriber radio terminals. The RBS may be connected to a backbone network, eg a public switched telecommunications network (PSTN) switch via a conventional transmission link, known as a backhaul link, thereby providing the plurality of subscribers with access to the PSTN. A single base station may serve several thousand subscribers. Communication between a subscriber's Network Terminal Equipment (NTE) and its corresponding RBS is via a local wireless Radio Frequency (RF) link using a known Air Interface Protocol (AIP). Each local wireless link between a RBS and a subscriber's NTE comprises an uplink from a subscriber antenna, part of a Residential Subscriber System (RSS) installed at the subscriber's premises, to the RBS antenna, and a downlink transmitting from the RBS to the subscriber's RSS. Downlink beam coverage is provided in a nominally hexagonal cellular pattern. Each RBS operates either an omni-directional beam or a plurality of broad sectorized beams encompassing all subscribers in a cell or sector for receive and transmit, whereas each subscriber's RSS may operate a directional pencil beam directed at the RBS for receiving and transmitting.
• In FIG. 3,[0064]RBS301 provides coverage for Acell303.Cell303 may be divided into sectors, for example 3 sectors each covering a 120 degree portion of the cell. It would be appreciated by those skilled in the art that other common configurations of cellular transmission may be used, for example, tri-cellular. According to the preferred embodiment, each timeslot in the RBS's downlink beam comprises a logical channel. A logical channel may be transmitted between RBS and subscriber's RSS on a specific carrier frequency (which may be called a “physical channel”). A logical channel transmitted to/fromRBS301 from/to a subscriber RSS may be uniquely identified by a logical channel identification data. Each logical channel is intended to be shared by a group of subscribers' RSS each of which are connected to Internet terminals which have been registered as users. In a group of registered users, each user's RSS preferably includes a line intended for use with a NTE such as a telephone handset or fax and also a line intended for use with an Internet terminal such as a modem attached to a Personal Computer (PC)109. A group of registered users which share a specific logical channel transmitted to/fromRBS301 may comprise up to four subscribers whose premises are all located in the same cell,303, covered byRBS301. If the cell is sectorised, the members of the user group may be located in a single sector of the cell. In the example shown in FIG. 3, the RBS's user group which share a single logical channel transmitted to/fromRBS301 includessubscribers305,306,307 and308 incell303. The user group may be called a “closed” user group as data transferred on the group's shared logical channel is not intended to be listened to by any other users and preferably up to a maximum of four users must be registered users who have joined as members of the group before sharing the logical channel. Members of a closed user group may be given a password in order to join the group, thereby improving security.
• Preferably, each downlink PDU broadcast on the shared logical channel during a single frame by[0065]RBS301 to subscribers305-308 includes data representing a token. The token comprises a code denoting which of the subscribers305-308 may use the uplink transmission to transfer data toRBS301 in a next frame. Preferably,RBS301 and subscribers'305-308 RSSs are configured such that when the logical channel timeslot used by the group is required for circuit switched data the group suspend their use of the shared logical channel in order to give way to the circuit switched data.
• FIG. 4 of the accompanying drawings illustrates data which may be associated with a group of users, such as the closed user group illustrated in FIG. 3. Electronic signals representing the data may be stored and accessed by the user's RSSs and/or[0066]RBS301. As each user in the group is a subscriber of the FWA telecommunications network, each user's has a Permanent NTE Identifier (PNID). The PNID is used as a unique identifier which is used by the network operator for billing the customer, etc. A PNID may also be used by network equipment to route connections to a particular subscriber's NTE, etc. Each user group is given a Group Identifier (GID) which may be a unique value assigned to a group of users sharing a logical channel transmitted by a particular RBS. Thus, the GID for all users belonging to a particular group will be identical. Each user in the group is also preferably assigned a User Identifier (UID) which may be a unique identifier for each user in the group. A UID and GID are preferably allocated to a user during a user registration process described hereinbelow. Thus, each user in a closed user group may be uniquely identified by data representing their GID and UID, as well as their PNID. For example:

  	User	PNID	GID	UID
  	305	234	2	0
  	306	200	2	1
  	307	212	2	2
  	308	253	2	3

• FIG. 5 of the accompanying drawings details schematically components of the FWA system illustrated in FIG. 3. A[0067]RSS501 may be installed at each of the premises of users305-308.RSS501 comprises aRF antenna502 which may be connected to a Residential Transceiver Unit (RTU)503.RTU503 can transmit/receive RF signals to/fromantenna502 by using a Radio Modem Unit (RMU)504.RMU504 can communicate with PPM Application Specific Integrated Circuit (ASIC)505. Preferably, circuit switched traffic received atantenna502 is transferred to S/T chip506. Preferably, packet switched data is transferred fromPPM ASIC505 to ShareMOM component507.Share MOM component507 can communicate data withmicroprocessor508. Preferably,microprocessor508 executes instructions for converting data received atantenna502 into a form suitable for S/T chip506. The instructions preferably convert data by interfacing between a series of protocols according to the preferred embodiments described herein below.
• [0068]RSS501 may also comprise a RSS Board Unit (RBU)509.RBU509 comprises a S/T chip510 which is preferably capable of communicating with S/T chip506 ofRTU503. Data is transferred from S/T chip510 tologic component511.Logic component511 is capable of routing circuit switched data toALM component512.ALM512 may be connected to subscriber NTE equipment suitable for circuit switched traffic, forexample telephone handset513.Logic component511 preferably transfers packet switched data tomicroprocessor514.Microprocessor514 preferably executes instructions for converting data to/from a format compatible with V.34 commands according to protocols used by the preferred embodiments.Microprocessor514 may transfer converted data to V.24port515 and receive data for conversation from V.24port515. V.24port515 can communicate with the user'sInternet terminal equipment109 by means of a V.24serial interface529, which may be configured to be asynchronous or synchronous. Alternatively,user terminal109 may communicate withRSS501 by means of a purely digital line.
• [0069]RBS301 comprises anantenna516. Signals may be transferred to/fromantenna516 of the RBS from/toantenna502 of the RSS via a knownair interface530 preferably using RF links.Antenna516 is preferably connected to a Transceiver Microwave Unit (TMU)517.TMU517 preferably communicates with a Packet Data Unit (PDU) switch component518 by means of IF/base band signals. The PDU switch518 is preferably contained within a Transceiver Processor Module (TPM)519 ofRBS301.TPM519 also comprisesdigital signal processors520, which communicate with the PDU switch518 using AI (Air Interface) slots. Thedigital signal processors520 may comprise modems and/orISDN Terminal Equipment521. Thedigital signal processors520 may also be connected tomicroprocessor522 by means of an Internet Protocol (IP)/ Point to Point Protocol (PPP)router522.Microprocessor523 may be used to convert data received atantenna516 into a format suitable for routing across a PSTN, ISDN or digital leased line, for example the known E-1 format.Digital signal processors520 preferably transfer data to anE-1 switch523 by means of Access Node (AN) slots. The E-1 switch preferably givesRBS301 access to abackbone telecommunications network111, for example a PSTN or an ISDN by means of anE-1 backhaul cable525. Packet data being transferred to/fromRBS301 viatelecommunications network111 may be received byISP110 which is connected to the network.ISP110 may comprise modems for communicating data withtelecommunications network111 if it is a PSTN.ISP110 may compriseISDN Terminal Equipment527 for communicating withtelecommunications network111 if the network is an ISDN by means of S/T or E-1 signals.Modems526 and/orISDN terminal equipment527 may be connected to an IP/PPP router528 ofISP110.
• Alternatively, if[0070]ISP110 is connected directly toRBS301 by means of a digital leased line524 (this may be the case whenISP110 is also a telecommunications network operator), which typically provides more reliable and faster transfer of data between the ISP and the RBS.RBS301 may communicate data across the digital leasedline524 to a PPP/IP router528 ofISP110.
• An example of operation of the[0071]RBS301 and anInternet TE109 connected to a RSS installed for one ofsubscribers305 to308 which has been registered and joined as a member of a closed user group for sharing a logical channel transmitted byRBS301 may be as follows (it will be appreciated that substantially similar operation will occur for all other members of the user group, or for a member of any other user group sharing another single logical channel):
• A member of the user group wishing to web browse may turn on their[0072]Internet user terminal109 and operates conventional web browse software within the terminal, which generates packet switched data. The packet switched data is sent to and converted by the user'sRSS501, preferably by means of protocol stacks described hereinbelow, into a form which can be transmitted over the air interface.
• The RSS communicates packet switched data, over a known uplink access channel eg ALOHA, which is received by[0073]RBS301. The uplink transmitted packet switched data may be for example a service request for Internet services provided byInternet service provider110, or alternatively may be a short message, for example an e-mail message. The packet switched data may share the uplink transmission with the normal circuit switched connection requests which are transmitted by an RSS requesting bearer slot resources when subscribers wish to make circuit switched connections. Since the packet switched data shares the uplink transmission, and requests for circuit switched connections also occupy these transmissions, in the best mode herein the logical channels transferring packet switched data are configured to yield channel capacity typically when no or few timeslots are available for circuit switched data (which may be a preset number of timeslots selected to ensure a particular quality of service), giving priority to circuit switched connection requests in an attempt to ensure that circuit switched data transfer quality of service is of an acceptable level. Similarly, on the downlink transmission, the downlink transmission is similarly configured to give priority to circuit switched traffic.
• In a connectionless network service each packet of information between a source and destination network component travels independently of any other packet. In practice, FWA networks may be capable of operating in either a connectionless or a connection oriented mode. A datagram may comprise a self-contained package of data that carries enough information to be routed from a source to a destination network component independently of any previous and subsequent data exchanges. There may be a probability that any datagram may be lost or damaged before reaching its destination.[0074]
• Thus, there may be two reasons why connectionless bearer datagram services are preferred. Firstly, because there is an advantage in giving way to voice traffic relatively rapidly as system capacity is increasingly utilized, and secondly for achieving a quick reclamation of spare bandwidth when there is spare capacity available. Under some circumstances, the radio base station may request a subscriber to give up a timeslot used for packet switched data, to release that timeslot for circuit switched connections, not primarily because of lack of capacity in a sector as a whole, but for ease of management of circuit switched connections, causing as little disruption as possible to circuit switched services.[0075]
• On the uplink, the connectionless bearer service comprises an uplink pilot packet having a relatively long training sequence and being self-contained. Because the training sequence is relatively long, receipt of the whole packet on the uplink is more likely to be received error-free. However, on the downlink, conventional Internet Protocol (IP) packets are preferably used.[0076]
• On the downlink, a downlink distribution logical channel is listened to continuously by members of the user group who share the logical channel. Data packets are broadcast from the radio base station on that downlink distribution logical channel for all four members of the user group. Each user's RSS may use IP to pick off data packets addressed to that particular RSS. Up to 128 downlink distribution channels may be accommodated, with four subscribers listening to each downlink distribution channel, giving a maximum capacity of 512 subscribers, assuming no yielding to circuit switched voice data traffic. For each sector covered by the RBS, a maximum number of logical channels may be 60, each timeslot comprising a logical channel. Thus, for each logical channel there is a closed user group of up to four subscribers listening to that channel.[0077]
• On the uplink, the four members of the user group may share one logical channel. To avoid conflicts of subscribers using a logical channel on the access uplink channel simultaneously and thereby colliding, uplink transmission is controlled by use of a token. Allocation of the token is made by transmission of a token address on the downlink. Within each logical channel, data packets being broadcast on the downlink may include a token address which specifies which subscriber of the user group sharing the logical channel has a right to transmit on the uplink, on a next frame. This token mechanism is intended to resolve contention of access channel resources on the uplink.[0078]
• The service request may be decoded at the RBS and recognized as being an Internet data service request, rather than a connection set-up request.[0079]
• The RBS sends the packet switched data to its[0080]TPM519. The TPM's microprocessor and IPP/PP router522 preferably contains a database listing RSS identification data, and corresponding Internet protocol addresses for user terminals at those respective RSSs. The database information may be configured during provisioning or registration of the RSSs, or provisioning or registering of the asymmetric packet switched data service on existing RSSs. The TPM determines from the air interface protocol address received, a corresponding Internet Protocol address of a user terminal at that RSS, from the database. The TPM may convert the received packet switched data from a form suitable for carrying over the wireless link to a form which is recognizable byInternet service provider110. The TPM may communicate withInternet service provider110 by a variety of mechanisms, depending on configuration of the RBS. Where the RBS is connected toInternet service provider110 by private leasedline524, the request for packet switched data (an Internet service request) is forwarded directly toInternet service provider110 over the line.Internet service provider110 responds by providing packet switched Internet data services which are returned over leasedline524 to the RBS which transmits the packet switched data via itsTMU517 over the sectorized downlink beam on a downlink distribution channel carried on an logical channel as a downlink carrier frequency. The downlink distribution channel is received by a plurality of RSSs, including the RSS which originated the packet switched data requesting the Internet service data. The RSS which originated the request for Internet service data receives the retrieved packet switched Internet service data and recognizes that the Internet service data is addressed to itself, by virtue of the conventional Internet protocol and converts into a form suitable foruser terminal109.
• Alternatively, where leased[0081]line524 is not used, the RBS signals to itsE1 switch523 to set up a circuit switched modem call overE1 line525 to theInternet service provider110 over thecommunications network111. The packet switched service request for packet switched Internet service data is sent from the RBS across the circuit switched connection toInternet service provider110. The Internet service provider responds by providing Internet service data over the circuit switched connection which is received at the RBS. On receipt of the packet switched Internet service data, the RBS forwards this packet switched data to itsTMU517 which transmits the packet switched data (Internet service data) on the downlink logical channel which is received by the RSS originating the service request. The RSS receives the packet switched Internet service data and recognizes that data according to the conventional Internet protocol and preferably sends it toInternet TE109 over the V.24line529.
• For example,[0082]user terminal109 connected to the RSS may have an Internet protocol address 47.10.11.1. However, whenuser terminal109 sends a request for Internet service data (packet switched data) to the RSS, this information is preferably translated into a PNID, that is to say an address which is recognized by the fixed wireless access protocols. Additionally, identification data used internally by the fixed wireless access system may be appended to the IP address, for example the UID, identifying the subscriber, and the GID identifying the user group sharing a downlink logical channel to which the user belongs. This identification information may be used to distinguish between different user terminals attached to a single RSS. Thus, the Internet application layer address 47.10.11.1 which is understood by Internet service provider414 is interworked with address data specific to the fixed wireless access system prior to transmission over the wireless link on the uplink contention access channel. Upon receipt at the RBS, the interworked data is translated into a format which is understandable byInternet service provider110, preferably by the RBS'sTPM519. The TPM may achieve the translation through use of a look up table which maps IP address against subscriber lines of the subscriber RSS, preferably stored in microprocessor and IP/PPP router522. For example, where the user terminal has a registered internal address. Within the table, there may exist mappings between IP address and PNID. For example:
• 47.11.11.2—234[0083]
• IP address PNID[0084]
• In response to the service request[0085]Internet service provider110 issues service data eg web pages or like computer data which is routed via thebackbone network111 toRBS301. On receipt of the service data, the RBS may segregate the Internet service provider's response service data and transfers the data toTMU517 for transmitting via the air interface as packet switched data. The service packet is transmitted by a sectored downlink beam, which covers an area containing several subscribers, eg one of cells302-304 where the user group is located. Although the downlink packet may be received by several subscribers' RSSs, only the RSS to which the downloaded service data is addressed in accordance with IP may decode the service data contacted within the packet. Typically, the amount of service data received in response to the service request is significantly larger in terms of number of bytes than the number of bytes in the service request message.
• FIG. 6 of the accompanying drawings illustrates schematically protocol stack intended for transferring data between a user's[0086]Internet terminal equipment109,RSS501,RBS301 andISP110 whennetwork111 comprises a PSTN. A protocol stack comprises a set of protocols governing information exchange of information between the components at a number of layers, and a set of interfaces governing exchange between adjacent protocol layers. The protocols are intended to exchange information between co-operating components, such as those shown in FIG. 5, wherein the components usually communicate by passing information across a local interface to so-called lower level protocols until a lowest, physical layer is reached. Data is transferred from one component to another using the physical layer protocol, and then passes upward via the interfaces until it reaches a corresponding level at a destination component. A common communications model including layers is the ISO/CCITT seven layer reference model. The lowest layer of the seven layer reference model is the physical layer. A data link layer is a next highest layer of the seven layer reference model. A Media Access Control (MAC) (sub)layer may exist between the physical layer and the data link layer. A network layer is the next highest layer of the seven layer reference model. A highest layer of the seven layer reference model is the application layer.
• The application layer for user[0087]Internet Terminal Equipment109 preferably comprisesapplication software601, which is stored as instructions in the PC's memory and executed on its processor.Software601 may be a World Wide Web browser or e-mail software or any other software application which may require Internet access. The network layer ofuser NTE109 may comprise Transmission Control Protocol (TCP). TCP is intended to provide error-free delivery of arbitrarily long messages, known as segments, with the data being released to a host system in a same order as an original transmission. The error free delivery may be achieved by means of a sliding window mechanism. The data link layer for theuser NTE109 may comprise IP. IP is intended to provide a connectionless datagram service, and a managed address structure for data transmission. An IP address can take one of four forms, class A to class D, which always occupies a total of 32 bits. A first group of bits define a class of the address; a second group of bits define an identity of a sub-network attach to the Internet. A final group of bits define an address of a host system within the sub-network. IP allows a long datagram to be fragmented into numbered packets, which can then be transmitted and reassembled in their correct sequence at a destination component. IP is intended to be used in conjunction with TCP. The MAC layer ofuser NTE109 may comprise PPP. PPP is intended to allow IP traffic to be handled on a serial line such as the V.24line529 connectingNTE109 toRSS501. The physical layer foruser NTE109 may comprise V.34 modem control protocol of the known Hayes Command Set. The V.34 commands are widely used for connecting PCs to modems and are used in the preferred embodiment so thatsoftware applications601 which require Internet access can be used with no or little modification as the present invention intends to provide Internet access to user terminal equipment over an FWA system as if it were connected to a conventional wire based network via a conventional modem. V.34 commands of userInternet terminal equipment109 may be transferred toRSS501 by means of V.24serial interface529.
• Suitably, the physical layer of[0088]RSS501 also comprises the V.34 modem control protocol and the physical layer protocol of the air interface. The MAC layer ofRSS501 preferably comprises PPP and the MAC layer protocol of the air interface. The MAC layer ofRSS501 may also comprise an Internet Wireless Unit (IWU). The IWU may also provide an interface between the RSS's MAC layer and its data link layer, its network layer and its application layer performing certain processes and converting data, including data generated and used by the processes, into a form readable by various components' layers. The data link layer ofRSS501 may comprise the data link protocol of the air interface. The network layer ofRSS501 may comprise the network layer protocol of the air interface. The physical layer ofRSS501 preferably communicates with the physical layer ofRBS301 viaair interface530.
• The physical layer of[0089]RBS301 preferably comprises V.34 modem control protocol and preferably the complete Hayes V.34 operation and the physical layer protocol of the air interface. The MAC layer ofRBS301 may comprise PPP and the MAC layer protocol of the air interface. The MAC layer may also include IWU which provides an interface between the RBS's MAC layer and its data link layer, its network layer and its application layer. The data link layer ofRBS301 preferably comprises IP and/or the data link layer protocol of the air interface. The network layer ofRBS301 preferably comprises TCP and/or the network layer protocol of the air interface.
• The physical layer of[0090]RBS301 preferably communicates with the physical layer ofISP110 by means of aPSTN modem link525. The physical layer ofISP110 preferably comprises the Hayes V.34 protocol. The MAC layer ofISP110 preferably comprises PPP. The data link layer ofISP 110 preferably comprises IP. The network layer ofISP110 preferably comprises TCP. The application layer ofISP110 preferably comprisessoftware602 which provides Internet services compatible with services of the kind required by the user'ssoftware application601. TheISP application software602 may act as a server providing WWW information, e-mail accounts and the like.
• FIG. 7 of the accompanying drawings illustrates schematically protocol stacks intended for transferring data between a user's[0091]Internet terminal equipment109,RSS501,RBS301,ISP110 wherenetwork111 comprises an ISDN. The application layer for userInternet terminal equipment109 preferably comprisesapplication software701 which may be identical or substantially similar toapplication software601. The network layer ofuser NTE109 may comprise TCP. The data link layer for theuser NTE109 may comprise IP. The physical layer foruser NTE109 may comprise V.34 modem control protocol of the known Hayes Command Set. V.34 commands of the userInternet terminal equipment109 may be transferred toRSS501 by means of V.24serial interface529.
• Suitably, the physical layer of[0092]RSS501 also comprises the V.34 modem control protocol and the physical layer protocol of the air interface. The MAC layer of RSS preferably comprises PPP and the MAC layer protocol of the air interface. The MAC layer may also comprise IWU. The IWU may also provide an interface between the RSS's MAC layer and its data link layer, its network layer and its application layer. The data link layer ofRSS501 preferably comprises the data link layer protocol of the air interface. The network layer ofRSS501 preferably comprises the network layer protocol of the air interface. The physical layer ofRSS501 preferably communicates with the physical layer ofRBS301 via theair interface530.
• The physical layer of[0093]RBS301 preferably comprises the V.34 modem control protocol and preferably the complete Hayes V.34 operation and the physical layer protocol of the air interface. The MAC layer ofRBS301 may comprise PPP and the MAC layer protocol of the air interface. The MAC layer may also include IWU which provides an interface between the RBS's MAC layer and its data link layer, its network layer and its application layer. The data link layer ofRBS301 preferably comprises IP and/or the data link layer protocol of the air interface. The network layer ofRBS301 preferably comprises TCP and/or the network layer protocol of the air interface. The Physical layer ofRBS301 preferably communicates with the physical layer ofISP110 by means of Basic Rate ISDN (BRI)525. The physical layer ofRBS301 preferably comprises the known V.120 protocol and the known 1.431 protocol.
• Suitably, the physical layer of[0094]ISP110 comprises the known 1.430/1.431 protocol. The MAC layer ofISP110 preferably comprises PPP. The data link layer ofISP110 preferably comprises IP. The network layer ofISP110 preferably comprises TCP. The application layer ofISP110 preferably comprisessoftware application702 which may be identical or substantially similar tosoftware application602.
• FIG. 8 of the accompanying drawings illustrates schematically protocol stacks intended for transferring data between a users[0095]Internet terminal equipment109,RSS501,RBS301 andISP110 whenISP110 is connected toRBS301 by means of a digital leasedline524. The application layer for userInternet terminal equipment109 preferably comprises application software801, which may be identical or substantially similar to asoftware application601. The network layer ofuser NTE109 preferably comprises PPP. The network layer may also comprise TCP and/or IP. Alternatively, layers between the application layer and the network layer of the seven layer reference model (ie presentation layer, session layer, transfer layer) may comprise TCP and/or IP. The data link layer ofuser NTE109 preferably comprises IP tunnel. The MAC layer ofuser NTE109 preferably comprises the known 802.2 protocol. The physical layer ofuser NTE109 preferably comprises the known 802.3 protocol. Data may be transferred from the physical layer ofuser NTE109 to the physical layer ofRSS501 by means of Ethernet (defined in ISO 802.3).
• Suitably, the physical layer of[0096]RSS501 may comprise 802.3 protocol and the physical layer protocol of the air interface. The MAC layer ofRSS501 may comprise the 802.2 protocol and the MAC layer protocol of the air interface. The data link layer ofRSS501 may comprise IWU and the data link layer protocol of the air interface. The IWU may provide an interface between the RSS's data link layer, its network layer and its application layer. The network layer ofRSS501 preferably comprises the network layer protocol of the air interface. The physical layer ofRSS501 preferably communicates with the physical layer ofRBS301 viaair interface530.
• The physical layer of[0097]RBS301 preferably comprises the known 1.430 protocol and the physical layer protocol of the air interface. The MAC layer ofRTBS301 preferably comprises the known 802.2 protocol and PPP and the MAC layer protocol of the air interface. The data link layer ofRBS301 may comprise IP tunnel and the data link layer protocol of the air interface. The data link layer ofRBS301 may also comprise IWU. The IWU may provide an interface between the RSS's data link layer and its network layer and its application layer. The network layer ofRBS301 preferably comprises the network layer protocol of he air interface.RBS301 preferably communicates withISP110 by means of digital leasedline524.
• The physical layer of[0098]ISP110 preferably comprises 1.430 protocol. The MAC layer ofISP110 preferably comprises PPP. The data link layer ofISP110 preferably comprises IP. The network layer ofISP110 preferably comprises TCP. The application layer ofISP110 preferably comprisessoftware application802, which may be identical or substantially similar tosoftware application602.
• FIG. 9 of the accompanying drawings illustrates a format of a Packet Data Unit (PDU) used by the preferred embodiment's MAC layer protocols on a downlink logical channel broadcast by[0099]RBS301 to a closed user group which shares the logical channel. Preferably, the downlink PDU comprises a substantially unmodified standard IP packet. Each downlink PDU may comprise three 8 bit data lines, each data line may comprise one or more data fields. Each bit in a data line may be labeled with a reference numeral 0-7, with 0 being a least significant bit of the data line and 7 being a most significant bit of the data line. Afirst data line901 of the downlink PDU preferably comprises four data fields.Bits0 and1 ofdata line901 may comprise tokenaddress data field907. The token address field is used to indicate which user of a user group sharing the same logical channel identified by a logical channel number and/or the GID can transmit in a next frame. The value stored in thetoken address field907 may be a numerical value between 0 and 3, each value corresponding to a UID of a user in the group.Bits2 and3 ofdata line901 may comprise a destinationaddress data field906. The destinationaddress data field906 is used to distinguish which of the different users of the user group sharing the logical channel identified by the GID is intended to read the PDU. The value stored in thedestination address field906 may be a numerical value between 0 and 3, corresponding to a UID of a user in the user group.Bits4 and5 ofdata line901 may comprise aGID field905. The GID field is used to distinguish between different user groups. The value stored in theGID data field905 may be a numerical value between 0 and 3.Bits6 and7 ofdata line901 comprise atype data field904. The type data field is used to distinguish between different downlink MAC message types. The value stored in thetype data field904 may be a numerical value between 0 and 3, each values used to denote a type of message as defined herein below:
• 0 system broadcast[0100]
• 1 user data[0101]
• 2 MAC control[0102]
• 3 reserved[0103]
• A[0104]second data line902 of the PDU preferably comprises two data fields.Bits0 to6 ofdata line902 preferably comprise a Logical Channel Number (LCN)909. A logical channel is uniquely identified by its LCN and the GID. Each LCN/GID is mapped onto a physical channel which delivers 32 Kb/s in the downlink direction and around 14 Kb/s in the uplink direction. The value stored in theLCN data field909 may be a value between 0 and 127, corresponding to a unique LCN for the logical channel upon which the Pdu is being transmitted.Bit7 ofdata line902 comprises an M/F bit field908. The M/F bit field908 is used to indicate whether the PDU is the final packet to be transmitted by the RBS or whether there are more the follow. The value stored in the M/F bit field may be 0 or 1, wherein thevalue 1 indicates there are more PDUs to follow and thevalue 0 indicates no more PDUs to follow. Athird data line903 of the downlink PDU preferably comprises a single 8 bit cyclic redundancy check (CRC)field910. TheCRC field910 is preferably used for error detecting in the downlink PDU.
• FIG. 10 of the accompanying drawings illustrates a format of a PDU used by the preferred embodiment's MAC layer on the uplink. The uplink PDU may be a pilot PDU for use in a connectionless datagram service. The uplink pilot packet may have a relatively long training sequence and may be self-contained. As the training sequence is relatively long, receipt of the whole packet on the uplink is more likely to be error-free. Each uplink PDU may comprise two 8 bit data lines, each data line comprising one or more data fields. Each bit in a data line may be labeled with a[0105]reference numeral 0 to 7, which 0 being a least significant bit of the data line and 7 being a most significant bit of the data line. Afirst data line1001 of the uplink PDU preferably comprises four data fields.Bits0 and1 ofdata line1001 may comprise senderaddress data field1003. The send address data field is used to identify a sender of the uplink PDU. The values stored in senderaddress data field1003 may be a numerical value between 0 and 3, corresponding to a UID of a particular user in the group.Bits 2 and 3 ofdata line1001 may comprise areservation data field1004. The reservation data field may contain a value corresponding to a UID of a user who has reserved the uplink PDU in advance for making data transmissions.Bits4 and5 ofdata line1001 may compriseGID data field1005. The GID data field is used to distinguish between different user groups. The value stored in theGID data field1005 may be a numerical value between 0 and 3.Bits6 and7 ofdata line1001 may comprise atype data field1006. The type data field is used to distinguish between different uplink MAC message types. The value stored in thetype data field1006 may be a numerical value between 0 and 3, each value used to denote a type of message as defined hereinbelow:
• 0 system broadcast[0106]
• 1 user data[0107]
• 2 MAC control[0108]
• 3 reserved[0109]
• A value 3 (reserved) stored in uplink[0110]type data field1006 and/or downlinktype data field904 may indicate that the next uplink and/or downlink packet respectively, has been reserved for use by a particular member of the user group.
• A[0111]second data line1002 of the uplink PDU preferably comprises two data fields.Bits0 to6 ofdata line1002 may comprise aLCN data field1007. A value stored inLCN data field1007 may be a value between 0 and 127, corresponding to a unique LCN for the logical channel upon which the PDU is being transmitted.Bit7 ofbit line1002 may comprise an M/F it field1008. The M/F bit field1008 is used to indicate whether the uplink PDU is a final packet to be transmitted to the RBS of whether there are more to follow. The value stored in the M/F bit field1008 may be 0 or 1, where thevalue 1 indicates there are more PDUs to follow and thevalue 0 indicates no more PDUs to follow.
• FIG. 11 of the accompanying drawings illustrates functional components of[0112]RSS501 andRBS301's MAC layers and higher layers. The functional components may comprise the IWU contained in the protocol stacks ofRSS501 andRBS301. Functional components of the RSS's MAC layer comprise Air Interface Closed User Group (AICUG)MAC1101 which may be responsible for controlling transmission of uplink packets and reception of downlink packets to the RSS.AICUG MAC1102 can communicate withAICUG access control1102, which may be responsible for routing messages and access control for system messages between the RSS andRBS301.
• Functional components of the RBS's MAC layer may include[0113]AICUG1106 which may be responsible for controlling reception of uplink packets and transmission of downlink packets by the RBS. Functional components of the RBS's MAC layer may also include AICUGglobal service manager1102, which may be responsible for overall AICUG service management. Functional components of the RBS's MAC layer include AICUGLCN resource manager1108, responsible for the RBS's management of logical channels preferably including (logical channel allocation/de-allocation, physical channel switching, logical channel suspend and resume operations as described hereinbelow). Functional components of the RBS's MAC layer may also include AICUGuser registration component1109, which may be responsible for registering network subscribers as users. Functional components of the RBS's MAC layer may also include airside resource manager1110, which is responsible for allocating resources such as timeslots over the air interface protocol.
• Air[0114]side resource manager1110 may communicate with AICUG global service manager1107. The AICUG global service manager1107 may also communicate with AICUGuser registration component1109. The AICUG global service manager component1107 may also communicate with AICUGLCN resource manager1108. AICUGLCN resource manager1108 may communicate withAICUG MAC1106. The RSS'sfunctional components1101 and1102 may be processes being executed onmicroprocessor514 ofRBU509 and/ormicroprocessor508 ofRTU503. The RBS'sfunctional components1106 to1110 may be processes being executed onmicroprocessor component522 or another processor in the RBS'sTPM519.
• AICUG[0115]1102 ofRSS501 may communicate with AICUG global service manager1107 ofRBS301 by means ofALOHA communications channel1105.Communications channel1105 may also/alternatively comprise a broadcaster SAS channel and/or an air interface protocol LME channel.AICUG MAC1101 ofRSS501 may transfer control data to/fromAICUG MAC1106 ofRBS301 be means ofAICUG control channel1104. Data such as packet data containing Internet service requests may be transferred betweenAICUG MAC1101 ofRSS501 andAICUG MAC1106 ofRBS301 by means ofAICUG data channel1103.
• FIG. 12 of the accompanying drawings illustrates steps typically executed by the functional components illustrated in FIG. 11 when a FWA network subscriber uses[0116]Internet terminal109 for a session of accessing Internet data according to the preferred embodiment. Atstep1201 the subscriber is registered as a user of the FWA Internet access system. Atstep1202 the registered user joins a resource (ie logical channel) sharing closed user group.Steps1201 and1202 may be repeated for each user (up to a maximum of four) which may be registered and join as a member of the closed user group. Atstep1203 the user may access and transfer Internet data over the FWA system as described hereinabove with examples. At step1204 a question is asked whether airside resource manager1110 is requesting resource reallocation of the shared logical channel. This request may occur when the timeslot used as the group's logical channel is required for transmission of FWA circuit switched traffic (eg voice traffic), usually when no more spare air side time slots are available for the circuit switched traffic, or when a predetermined number of timeslots are occupied by circuit switched traffic. If the question asked atstep1204 is answered in the affirmative then control is passed to step1208 where the timeslot is yielded to circuit switched traffic (called a “suspend” operation). The suspended timeslots may be reused as the group's logical channel when a spare timeslot becomes available (called a “resume” operation).
• At step[0117]1205 a question is asked whether airside resource manager1110 is requesting a physical channel switch. The physical channel switching request may occur in order to ease soft call blocking on FWA circuit switched traffic. If the question asked atstep1205 is answered in the affirmative then control is passed to step1209 where a physical channel switching process is performed. If the question asked atstep1205 is answered in the negative then control is passed to step1206.
• At step[0118]1206 a question is asked whether the user has lost contact with the RBS. This loss of contact may occur during either a physical channel switch or a spend/resume operation. If the question asked atstep1206 is answered in the affirmative then control is passed to step1210. Atstep1210 the user's Internet TE is required to re-synchronize itself with its closed user group. If the question asked atstep1206 is answered in the negative then control is passed on to step1207.
• At step[0119]1207 a question is asked whether the user desires to end the session. If he question asked atstep1207 is answered in the negative then control is passed back tostep1203. If the question asked atstep1207 is answered in the affirmative, then control is passed to step1211 where a user de-registration process is performed.
• FIG. 13 of the accompanying drawings illustrates steps performed during[0120]user registration step1201. Atstep1301 the user makes a registration request to AICUG global service manager1107 (preferably using this AICUG access control1102). Atstep1302 the global service manager allocates a GID and a UID to the user. Atstep1303 the global service manager establishes an association between the user and the GID and UID created for the user atstep1302 by creating and storing a mapping between the user's PNID and the unique UID/GID pair. Atstep1304 the global service manager allocates one or more logical channel (according to current resource usage situation) to the user. Atstep1305 the global service manager assigns an address for each logical channel allocated to the user. As a result ofstep1305 the registered user may be identified by their GID, LCN and address. However, the GID, LCN and address identification is not unique to the user in the sense that the user may join more than one logical channel sharing closed user group.
• FIG. 14 of the accompanying drawings illustrates steps which may be performed when the user joins a closed user group at[0121]step1202. Three states may be associated with a particular logical channel. The states may comprise Inactive, Active and Suspended. Storage space, eg a variable, in a storage unit may be reserved for storing data describing the state of each logical channel which may be used by a closed user group. If a particular logical channel is not being used by any user group then its state may be set to Inactive. Atstep1401 if the registered user is the first user to join the closed user group during the session then the logical channel's state may be set to Active. Atstep1402LCN resource manager1108 sends a resource allocation request for the logical channel allocated to the user atstep1304 to global service manager1107. Atstep1403 the global service manager sends the resource allocation request to airside resource manager1110.
• At the end of the session, at[0122]user de-registration step1211 the user'sAICUG access control1102 makes a de-registration request to global service manager1107. Duringde-registration step1211 the global service manager de-allocates the UID allocated to the user and deletes the user's PNID to GID/UID mapping. During de-registration the global service manager also de-allocates the LCN/address pairs belonging to the user. The user'sAICUG access control1102 communicates with the global service manager during de-registration by means of the AICUG system control andmanagement channel1105. If the user being de-registered is currently the only registered user of the closed user group the group's state may be set to Inactive.
• FIG. 15 of the accompanying drawings illustrates steps which may be performed during suspend and resume[0123]transmission step1208. Atstep1501 the global service manager1107 which has received air side resource manager's1110 resource reallocation request made atstep1204 sends a yield resource request toLCN resource manager1108. Atstep1502 the LCN resource manager sends a suspend operation request to the RBS'sAIUG MAC1106. Atstep1503 the RBS's AICUG broadcasts a suspend message to the RSS AICUG MACs of all registered users of the closed user group sharing the logical channel requested. The RBS AICUG MAC also stops distributing the token which determines which user group member can make an uplink data transmission as use of the logical channel is to be suspended. Atstep1505 the start of the logical channel is set to Suspended.Steps1501 to1505 are associated with suspending use of the logical channel.
• At[0124]step1506 theLCN resource manager1108 sends a resource allocation request for its logical channel to airside resource manager1110 immediately after the logical channel has been suspended. Atstep1507 the air side resource manager sends a spare timeslot available message to the LCN resource manager. Atstep1508 the LCN resource manager passes on the time slot available message to global service manager1107. Atstep1509 the global service manager broadcasts a system message to the RSS AICUG MACs of all registered users of the closed user group sharing the logical channel. At step1510 the logical channel's state may be set to Active. Steps1506-1510 are associated with resuming use of the logical channel.
• FIG. 16 of the accompanying drawings illustrates steps which may be performed during physical[0125]channel switch step1209. Atstep1601 global service manager1107 sends a physical channel switch request toLCN resource manager1108. Atstep1602 the LCN resource manager modifies a LCN to Physical Channel Number (PCN) mapping by replacing a value corresponding to the current PCN with the new PCN enclosed in the global service manager's request. Atstep1603 the LCN resource manager sends a message indicating that a new PCN is to be used to the RBS'sAICUG MAC1106. Atstep1604 theRBS AICUG MAC1106 broadcasts the new PCN to theRSS AICUG MACs1101 of all registered users of the closed user group sharing the logical channel. On transmission of a next frame afterstep1604 theRBS AICUG MAC1106 changes the closed user group's LCN to the new PCN atstep1605. Afterstep1605 the physical channel denoted by the old PCN is free for allocation.
• FIG. 17 of the accompanying drawings illustrates steps which may be performed during[0126]group re-synchronization step1210. At step1701 a question is asked whether the user which has lost contact with their RBS is associated with another logical channel, ie the user was allocated more than one logical channel atstep1304. If the question asked atstep1701 is answered in the affirmative then control is passed to step1702. Atstep1702 the user'sAICUG access control1102 requests the user's GID/LCN to PCN mapping from global service manager1107 via a different GID/LCN. If the question asked atstep1701 is answered in the negative then control is passed to step1703.
• At step[0127]1703 a question is asked whether a circuit switched call is in progress. If the question asked atstep1703 is answered in the affirmative then control is passed to step1704. Atstep1704 the user'sAICUG access control1102 requests their GID/LCN to PCN mapping from the air interface protocol LME via the SAS channel ofcommunication channel1105. If the question asked atstep1703 is answered in the negative then control is passed to step1705. Atstep1705 the user'sAICUG access control1102 requests their GID/LCN to PCN mapping via the ALOHA channel ofcommunication channel1105. The GID/LCN to PCN mapping data is then transmitted to the user byRBS301 viaAICUG control channel1104.

Claims (30)

1. Communications apparatus for transferring packet switched data said apparatus comprising:

a radio base station capable of transmitting downlink data packets each said data packet being transferred in a specified single timeslot replicating over a plurality of time frames; and

at least one network subscriber equipment capable of receiving said downlink data packets;

wherein said subscriber equipments are joined as members of at least one user group, each said user group configured to receive said downlink packets in said specified single repeating timeslot only.

2. Apparatus according to

claim 1

, wherein said radio base station is configured to use a said specific timeslot for transmitting circuit switched data instead of packet switched data, to maintain quality of service of said circuit switched data.

3. Apparatus according to

claim 1

, wherein a said downlink data packet transmitted by said radio base station on a first said frame includes a token indicating which said member of said user group can transmit a said uplink data packet on a second said frame.

4. Apparatus according to

claim 1

, wherein said downlink data packet includes a destination address indicating which said member of said user group is intended to decode data contained in said packet.

5. Apparatus according to

claim 1

, wherein said user group comprises subscriber equipments located in a single cell covered by said radio base station.

6. Apparatus according to

claim 1

, wherein said user group members are registered before receiving or transmitting packets on said specific timeslot.

7. In a communications network, a method of communicating packet switched data comprising the steps of:

communicating a downlink data packet from a radio base station to at least one network subscriber equipment,

wherein said network subscriber equipment is registered as a member of a user group, said user group configured to receive said downlink packets in a specific single timeslot only.

8. The method according to

claim 7

, further comprising the step of yielding use of a said specific timeslot for transmission of circuit switched data instead of packet switched data to maintain quality of service of said circuit switched data transfer.

9. The method according to

claim 7

, wherein said downlink data packets transmitted on a first frame includes a token indicating which said member of said user group can transmit an uplink data packet on a second frame.

10. The method according to

claim 7

, wherein said downlink data packet includes a destination address indicating which said member of said user group is intended to decode data contained in said packet.

11. The method according to

claim 7

, wherein said user group comprises subscribers located in a single cell.

12. The method according to

claim 7

, wherein said members of said user group are registered before transmitting or receiving packets on said specific timeslot.

13. The method as claimed in

claim 7

, wherein said step of registering said subscriber equipment as a member of said user group comprises:

storing data describing an active state of a said timeslot.

14. A method of communicating packet switched data over a wireless link, said method comprising the steps:

registering at least one subscriber lines for receipt of said packet switched data on a downlink channel of said wireless link; and

communicating said packet switched data on said downlink channel;

wherein said downlink packet switched data carries an address of a group of registered said subscriber lines, for which said data is intended.

15. The method as claimed in

claim 14

, wherein said downlink channel comprises a repeating timeslot.

16. The method as claimed in

claim 14

, further comprising the step of transmitting a token on said downlink channel, said token comprising data describing an authorization for communicating an uplink timeslot of a next frame.

17. The method as claimed in

claim 16

, wherein said data packet comprises data identifying an individual said subscriber line to which said packet switched data is addressed.

18. The method as claimed in

claim 14

, further comprising the step of:

yielding use of said downlink channel for communication of circuit switched data, when a predetermined number of channels are occupied by circuit switched data.

19. A method of communicating packet switched data over a wireless link, said method comprising the steps of:

registering at least one subscriber line for receipt of said packet switched data on a downlink channel of said wireless link;

allocating a single uplink channel of said wireless link for receipt of packet switched data from a group of said subscriber lines;

transmitting a token data on said downlink, said token data indicating which of said registered subscriber lines has authorization to transmit on said uplink channel.

20. A method of communicating packet switched data over a wireless link, said method comprising the steps of:

receiving packet switched data on a downlink channel of said wireless link, said downlink channel allocated for receipt by a group of subscriber lines;

receiving a token data indicating authorization to transmit packet switched data on an allocated uplink channel; and

transmitting said packet switched data on said allocated uplink channel.

21. The method as claimed in

claim 20

, further comprising the step of re-synchronizing a said subscriber equipment to a said user group.

22. A method of registering a plurality of users of a communications network for receipt of packet switched data services over a wireless link, said method comprising the steps of:

receiving a registration request from a said network user;

in response to said registration request, allocating a user identification data to said user;

allocating an identification data to said user; and

allocating at least one logical communications channel to said user.

23. The method as claimed in

claim 22

, wherein said wireless link comprises a fixed wireless access radio link.

24. The method as claimed in

claim 22

, wherein said user identification data comprises data identifying an address of a user terminal equipment.

25. The method as claimed in

claim 22

, wherein said step of allocating a logical channel to said user comprises creating an association between said allocated user identification data and said allocated group identification data.

26. The method as claimed in

claim 22

, wherein said step of allocating at least one logical channel to said user comprises:

creating a mapping between data identifying said logical channel, data identifying said user, and data identifying a group allocated to said user.

27. The method as claimed in

claim 22

, further comprising the step of assigning an address to each said logical channel.

28. In a communications network operating a wireless link for communicating packet switched data to a network user of at least one channel of a plurality of channels, a method of re-synchronizing a user with a said channel to which said user has been previously assigned, said method comprising the steps of:

determining if said user is already assigned to a said logical channel;

if said user is already assigned to said logical channel, retrieving data identifying

a user group to which said user belongs;

a logical channel to which said group is assigned;

a physical channel to which said group is assigned; and

transmitting said data identifying said user group, said logical channel and said physical channel over said wireless link.

29. The method as claimed in

claim 28

, wherein said step of transmitting data comprises transmitting said data on a downlink.

30. The method as claimed in

claim 28

, further comprising the step of requesting transmission of said data identifying said user group, logical channel and physical channel.

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