US20140269550A1

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Publication number: US20140269550A1
Application number: US14/126,075
Authority: US
Inventors: William Webb
Original assignee: Neul Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2011-06-13
Filing date: 2012-06-13
Publication date: 2014-09-18
Also published as: US9544816B2; US20140153553A1

Abstract

A controller for assigning bandwidth to communications made over a communication network, the communication network having available to it a first type of bandwidth, which is not available to other users, and a second type of bandwidth, which is available to other users, the controller being configured to assign a communication the first type of bandwidth or the second type of bandwidth in dependence on an overall bandwidth available to the communication network.

Description

The invention relates to a controller configured to assign bandwidth to communications sent via a communication network.
A wireless network may be configured to operate without having been specifically allocated any part of the electromagnetic spectrum. Such a network may be permitted to operate in so-called white space: a part of the spectrum that is made available for unlicensed or opportunistic access. Typically white space is found in the UHF TV band and spans 450 MHz to 800 MHz, depending on the country. A large amount of spectrum has been made available for unlicensed wireless systems in this frequency range.
A problem with operating in white space is that the available bandwidth is variable and cannot be guaranteed. These limitations are well-matched to the capabilities of machine-to-machine networks in which there is no human interaction. Machine-to-machine networks are typically tolerant of delays, dropped connections and high latency communications.
Any network operating in the UHF TV band has to be able to coexist with analogue and digital television broadcast transmitters. The density of the active television channels in any given location is relatively low (resulting in the availability of white space that can be used by unlicensed systems). The FCC has mandated that systems operating in TV white space must reference a database that determines which channels may be used in any given location. This is intended to avoid interference with the TV transmissions and certain other incumbent systems such as wireless microphones.
For TV receivers (including those for digital TV (DTV)), there will inevitably be adjacent channels on which a strong transmission close to the TV receiver will interfere with TV reception. For example, the TV receivers may have image frequencies and poor adjacent channel rejection (ACR) on certain frequencies due to spurs on their local oscillators and limitations in their receive filters. These frequencies are often dependent on the specific receiver implementation.
In addition, some channels that the data base indicates are available to unlicensed networks will be subject to interference that makes them practically unusable. For example, a network operating in the UHF TV band may have to contend with interference from other unlicensed users, such as neighbouring communication networks or incumbent systems such as wireless microphones. A network may also suffer interference from cellular systems and emergency service communications at the band edges.
Another issue with which an unlicensed network must contend is that the bandwidth available to it will tend to vary with time. For example, a channel that the data base indicates should be available for use may be subject to intermittent interference from another user. Therefore, the network may find without warning that it has less bandwidth available to it than expected.
Therefore, there is a need for greater flexibility in allocating bandwidth.
According to a first embodiment of the invention, there is provided a controller for assigning bandwidth to communications made over a communication network, the communication network having available to it a first type of bandwidth, which is not available to other users, and a second type of bandwidth, which is available to other users, the controller being configured to assign a communication the first type of bandwidth or the second type of bandwidth in dependence on an overall bandwidth available to the communication network.
The controller may be configured to assign the communication the first type of bandwidth or the second type of bandwidth in dependence on a relative split in the overall bandwidth between the first type of bandwidth and the second type of bandwidth.
The controller may be configured to assign the communication the first type of bandwidth or the second type of bandwidth in dependence on a type of data comprised in the communication.
The controller may be configured to assign bandwidth to communications to be made over the communication network such that communications via the first type of bandwidth and the second of type bandwidth occur simultaneously over the network.
The controller may be configured to preferentially assign the first type of bandwidth to communications to be made over the communication network.
The controller may be configured to only assign a communication to the second type of bandwidth if there is insufficient of the first type of bandwidth to accommodate that communication.
The controller may be configured to control the operation of one or more base stations comprised in the communication network, the controller being configured to control a base station to operate in a first mode when communicating via the first type of bandwidth and in a second mode when communicating via the second type of bandwidth.
The controller may be configured to control the base station to, when operating in the first mode, disable one or more functions that are part of its second mode.
The controller may be configured to control the base station to disable one or more functions that enable the base station to communicate via bandwidth that is subject to interference.
The controller may be configured to control the base station to disable one or more of: antenna nulling, frequency hopping and communicating via narrow bandwidth channels.
The controller may be configured to, when assigning a communication the second type of bandwidth, schedule that communication so as to avoid interference and/or frequency masking.
The controller may be configured to, when assigning a communication the first type of bandwidth, not schedule that communication so as to avoid interference and/or frequency masking.
The controller may be configured to schedule a communication in dependence on the type of bandwidth it assigns to that communication.
The controller may be, configured to assign a communication an amount of bandwidth in dependence on the overall bandwidth available to the communication network.
The controller may be configured to assign a communication an amount of bandwidth in dependence on whether that communication is assigned the first type of bandwidth or the second type of bandwidth.
The controller may be, configured to control the operation of one or more base stations comprised in the communication network, the controller being configured to control a base station to communicate at a data rate that is dependent on the amount of bandwidth the controller has assigned to that communication.
The controller may be configured to determine a frequency hopping sequence comprising the first type of bandwidth and the second type of bandwidth for communicating over the network.
The controller may be configured to determine the frequency hopping sequence to use the first type of bandwidth for one hop and the second type of bandwidth for the following hop.
The controller may be configured to assign the communication the first type of bandwidth or the second type of bandwidth by allocating that communication a time slot on a hop in the frequency hopping sequence that uses that respective type of bandwidth.
According to a second embodiment of the invention, there is provided a method for assigning bandwidth to communications made over a communication network, the communication network having available to it a first type of bandwidth, which is not available to other users, and a second type of bandwidth, which is available to other users, the method comprising assign a communication the first type of bandwidth or the second type of bandwidth in dependence on an overall bandwidth available to the communication network.
According to a third embodiment of the invention, there is provided a communication network having available to it a first type of bandwidth, which is not available to other users, and a second type of bandwidth, which is available to other users, the communication network being configured to, if it determines that the first type of bandwidth available to it is insufficient to accommodate data to be communicated over the network, communicate at least some of that data using the second type of bandwidth.
The communication network may be configured for machine communication.
The communication network may be configured to operate in accordance with the Weightless protocol.
The first type of bandwidth may be licensed to the communication network.
The second type of bandwidth may be unlicensed.

For a better understanding of the present invention, reference is made by way of example to the following figures, in which:

FIG. 1 shows an example of a communication network;

FIG. 2 shows an example of a controller and associated radio;

FIG. 3 shows an example of a process for allocating bandwidth in a communication network;

FIG. 4 shows examples of how bandwidth might be reduced;

FIG. 5 shows an example of scheduling a communication to avoid a particular frequency;

FIG. 6 shows an example of antenna nulling; and

FIG. 7 shows an example of a controller.

The following description is presented to enable any person skilled in the art to make and use the system, and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art.

The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

A communication network may comprise a controller for allocating bandwidth to communications to be made over the network. The network may have two different types of bandwidth available to it: one type which is not available to other users and another which is available to other users. The controller may assign a communication to either type of bandwidth, depending on the overall bandwidth available to the communication network.

The first type of bandwidth may be bandwidth that is licensed to the communication network. This bandwidth is specifically assigned to the communication network and may not be used by users operating outside of the network. Typically this type of bandwidth is assigned by some government body responsible for regulating spectrum usage. The second type of bandwidth may be unlicensed bandwidth. This bandwidth is open to all, and any network operating using unlicensed bandwidth has to deal with users operating outside of the network using the same frequency space. The bandwidth will usually have been opened to unlicensed users by the government body responsible for regulating spectrum usage.

Wireless systems tend to operate either in licensed spectrum or in unlicensed spectrum. For example, cellular systems operate solely in licensed spectrum, whereas WiFi networks operate solely in unlicensed spectrum. However, there may be benefits in combining operation in the two different types of spectrum and the respective modes of operation they require of the network devices.

An example of a network in which licensed and unlicensed spectrum might be beneficially employed is one that is configured to operate in white space. Such a network might be configured to operate in accordance with the Weightless protocol for machine communications. Such networks typically require around four 8 MHz channels to operate effectively, although they can cope with fewer channels by reducing data rates. Usually there will be more than four channels available in white space for the network to use. However, sometimes the number of available channels may fall below four. For example, congestion caused by other unlicensed users might render one or more channels unusable. For an operator that wants to provide a high quality of service to customers, the risk of having to reduce data rates due to congestion can be unacceptable.

An alternative is to acquire licensed bandwidth that the network alone would be permitted to use. There would be no risk of congestion from other users because no other users would be entitled to use that part of the spectrum. However, spectrum purchase is often expensive. Typically, an operator would want to keep the amount of spectrum it buys to a minimum.

A suitable compromise is to purchase a minimal amount of licensed bandwidth for the network. A suitable amount might be, for example, two channels. The purchased bandwidth will typically not be sufficient on its own to meet the traffic requirements of the network. It may, however, be sufficient to maintain a minimally acceptable level of service when none of the unlicensed bandwidth available to the network is usable. The network is preferably able to use both licensed and unlicensed bandwidth simultaneously. If the network has two channels of licensed spectrum available to it, this should result in at least four channels being available to the network, even when the unlicensed part of the spectrum is subject to congestion. When congestion is severe enough for none of the unlicensed channels to be available, the network would still have the licensed channels available to it. Even two channels would allow some level of service to be provided.

The licensed and unlicensed spectrum could come from many sources. The preferred part of the unlicensed spectrum is TV white space. However, unlicensed access to other bands might be possible in future, including e.g. VHF bands, military bands below 1 GHz, or selected bands above 1 GHz. The preferred part of the licensed spectrum is that which is close to, or interleaved with, the TV bands. However, any licensed part of the spectrum is suitable, including e.g. 900 MHz, 1.8 GHz and other bands.

One or more embodiments of the invention will now be described with specific reference to a wireless network in which the controller is part of a base station controller. This is for the purposes of example only and it should be understood that the mechanisms for allocating bandwidth described herein may be implemented in any suitable network device, irrespective of what particular role that device plays within the network.

An example of a wireless network is shown inFIG. 1. The network, shown generally at104, comprises one ormore base stations105 that are each capable of communicating wirelessly with a number ofterminals106. Each base station may be arranged to communicate with terminals that are located within a particular geographical area or cell. The base stations transmit to and receive radio signals from the terminals. The terminals are suitably entities embedded in machines or similar that communicate with the base stations. Suitably the wireless network is arranged to operate in a master-slave mode where the base station is the master and the terminals are the slaves.

Thebase station controller107 is a device that provides a single point of communication to the base stations and then distributes the information received to other network elements as required. That is, the network is based around a many-to-one communication model. The network may be arranged to communicate with a client-facingportion101 via theInternet102. In this way a client may provide services to the terminals via the wireless network.

Other logical network elements shown in this example are:

- Core network. This routes traffic information between base stations and client networks.
- Billing system. This records utilisation levels and generates appropriate billing data.
- Authentication system. This holds terminal and base station authentication information.
- Location register. This retains the last known location of the terminals.
- Broadcast register. This retains information on group membership and can be used to store and process acknowledgements to broadcast messages.
- Operations and maintenance centre (OMC). This monitors the function of the network and raises alarms when errors are detected. It also manages frequency and code planning, load balancing and other operational aspects of the network.
- White space database. This provides information on the available white space spectrum.
- Client information portal. This allows clients to determine data such as the status of associated terminals, levels of traffic etc.

In practice, many of the logical network elements may be implemented as databases running software and can be provided on a wide range of platforms. A number of network elements may be physically located within the same platform.

A network such as that shown inFIG. 1 may be used for machine-to-machine communications, i.e. communications that do not involve human interaction. Machine-to-machine communications are well-matched to the limitations of operating in white space, in which the bandwidth available to the network may vary from one location to another and also from one time instant to the next. Machines are able to tolerate the delays and breaks in communication that can result from these varying communication conditions. Services can be provided in non real-time; low latency is not important as long as data is reliably delivered.

The communication network shown inFIG. 1 is configured to operate in an unlicensed part of the spectrum. The network may benefit from also having licensed bandwidth available to it. The network is therefore preferably configured to be able to operate using both unlicensed and licensed bandwidth. Devices operating in the network (such as base stations, base station controllers, terminals etc.) are preferably able to switch between licensed and unlicensed modes of operation. For most devices, this may primarily involve disabling specific functions designed to address the challenges of operating in an unlicensed part of the spectrum (more details of this are given below).

The communication network preferably comprises a controller for allocating communications to either licensed or unlicensed bandwidth. The controller may be a stand-alone device or form part of another device, such as a base station. In a preferred embodiment, the controller is implemented by a base station controller. The base station controller may assemble frames. It may also make scheduling decisions and plan radio-related resources, including bandwidth allocation, frequency planning, code assignment synchronisation word planning and load balancing. Base stations may be simple devices that take pre-formatted frames of information and transmit them under the control of their respective base station controller.

An example of a controller (e.g. a base station controller) together with an associated radio (e.g. a base station) is shown inFIG. 2. The controller (or at least part of it) is shown at201. The controller comprises anetwork layer203 and acontrol layer204, both of which are implemented in software. The control layer is configured to format the data to be transmitted over the network into frames. The frames are suitably entire frames, including control and header information. These frames may then be passed, e.g. via an Ethernet connection, to theradio202. The radio comprises a thin layer of embeddedfirmware206 for presenting the formatted data to theMAC207 and aphysical layer208 for transmitting signals over the air interface.

The result is an architecture in which a simple physical device acts as the “base station” in the conventional sense, by transmitting and receiving signals over the air interface. The “base station controller” controls the operation of the “base station”. Moving more of the intelligence into the software renders the controller readily transferrable to different physical devices.

The controller may be implemented as a virtual machine running on a PC. Preferably the controller can be moved to a new machine without having to be adapted to the particular physical attributes of that machine. The radio might be implemented by a modem. The PC might be connected to a modem over an Ethernet connection.

An example of a process for assigning bandwidth to a communication is shown inFIG. 3. The process starts instep301. Instep302, the controller may determine whether the communication is subject to any time constraints, as this may affect the amount and type of bandwidth available. Instep303, the controller determines what bandwidth will be required to transmit the communication. In this example the controller is arranged to preferentially assign licensed bandwidth, as it is less likely to suffer from interference. The controller determines instep304 whether there is sufficient licensed bandwidth available to accommodate the communication. If yes, the controller may cause the base station to enter the licensed mode of operation (step305). The communication is scheduled to be sent using licensed bandwidth instep306. If the answer atstep304 is no, the controller may cause the base station to enter its unlicensed mode of operation (step307). The communication is then assigned the required unlicensed bandwidth instep308. The process terminates instep309.

The controller may consider a relative split between the licensed and unlicensed bandwidth available to a base station when deciding what type if bandwidth to assign to a particular communication. The controller might also consider the type of data being transmitted. For example, some data may be associated with a time limit or a particular quality of service requirement that requires it to be transmitted more quickly or via bandwidth that is more likely to result in a successful transmission. Some data may have intrinsic qualities that make it more suitable for being transmitted via one type of bandwidth over the other. For example, voice data might be better suited to being transmitted via licensed bandwidth. The controller might also be configured to prefer one type of bandwidth over the other. For example, the controller might be configured to only assign a communication to the unlicensed bandwidth if there is not enough licensed bandwidth available to accommodate it. Licensed bandwidth may be preferred because it is less subject to interference. If there is a cost associated with using licensed bandwidth, e.g. under a “pay per use” scenario, then the controller may prefer unlicensed bandwidth.

The bandwidth available to the network may be divided into channels. Channels may have different bandwidth depending on which part of the spectrum they come from. For example, TV bands tend to use 6 MHz or 8 MHz channels, while some cellular spectrum is configured on a 5 MHz bandwidth and other spectrum on a narrower band than this. In this example the unlicensed channels are wider than the licensed channels; the reverse may also be true.

The network may be configured to use frequency hopping. Suitably the controller is arranged to determine a frequency hopping sequence for the base stations it controls. The controller may obtain a list of channels that are available to each base station from the network's white space database. The controller may reject one or more channels from the list if it has determined that those channels are practically unusable because of interference. The controller may generate a hopping sequence for each base station to include the remaining channels. Suitably the hopping sequences are arranged so that neighbouring base stations use different frequencies at any one time.

The controller may generate a frequency hopping sequences to include both licensed and unlicensed channels. Each base station may only communicate on one channel at a time. Each base station may only communicate via unlicensed or unlicensed bandwidth at any one time. The network as a whole, however, will be able to communicate via both types of bandwidth simultaneously since at any given moment one base station may be communicating via licensed bandwidth while another is communicating via unlicensed bandwidth. For each base station, the type of bandwidth can change from one hop to the next. The width of a channel may also change from one hop to the next.

The controller may generate a series of frames for communication by a base station. The controller may instruct the base station to transmit each frame at a particular time and on a particular frequency in the hopping sequence. Each frame may be communicated on a different frequency in the hopping sequence. Consequently, one frame may be allocated a different type and amount bandwidth from the one preceding it.

Each frame may comprise uplink and downlink sections. Frequency hopping may occur at the frame rate, so that both uplink and downlink sections of a frame use the same channel. In one example each frame is 2 seconds long. The controller suitably assigns bandwidth to both whole frames and individual communications within those frames. Preferably the uplink and downlink portions of each frame are divided into a series of time slots that the controller can assign to communications between the base station and terminals. The controller may divide the overall bandwidth between different communications by assigning each communication a time slot in a frame to be transmitted on a particular hop in the frequency hopping sequence. If access to unlicensed access is good, the number of unlicensed channels in the frequency hopping sequence may be relatively high and the controller will be more likely to assign a communication to an unlicensed channel. The reverse is also true. If performance on some of the unlicensed channels worsens, the controller may remove one or more of those channels from the hopping sequence, thereby shifting the balance towards licensed channels.

The long term balance between licensed and unlicensed spectrum might change over time. For example, an operator might progressively acquire more spectrum and shift usage towards licensed access. Alternatively, experience may develop an operator's confidence in unlicensed spectrum. Such an operator may decide to use their licensed spectrum for activities such as transmitting voice and shift other communications (e.g. machine communications) towards greater use of unlicensed spectrum.

The scheduling system (which may be implemented by the controller) is preferably able to manage any degradation in data rates as the network moves between licensed and unlicensed access, and between different channel bandwidths. For example, lower data rates may have to be implemented when operating in an unlicensed part of the available spectrum, in order to accommodate additional spreading or error control coding to deal with potential interference. Data rates may also have to be adjusted to account for different channel widths. The controller may control the base station to use a particular data rate. The terminals may be instructed to use a particular data rate by the base station (acting under the control of the controller).

Operating in licensed and unlicensed parts of the spectrum is different, mainly because extra functions may be required to successfully use unlicensed spectrum. Therefore, the network is preferably one that is designed to work using unlicensed frequencies. The network may have two modes of operation: licensed and unlicensed. Certain features of unlicensed mode may be disabled when operating in licensed mode. The disabled features may particularly be intended to address interference problems that a network might encounter in an unlicensed part of the spectrum. Some examples are given below.

Using a Reduced Bandwidth

One in way in which the controller may control a base station to address problems with interference is by limiting the bandwidth that the base station and its associated terminals are permitted to use. The controller may detect that a particular channel is subject to interference, characterise the nature of that interference and determine a reduced channel bandwidth accordingly. This can enable the base station to use a channel that would otherwise not be practicably usable. It also assists the network to meet the stringent adjacent channel protection requirements for white space.

The communication device may have a variety of different options at its disposal for communicating over part of the bandwidth of an available channel. Some of these options are illustrated inFIGS. 4(a) to (d). In the most straightforward case, the communication device may simply use only part of the channel, leaving the centre frequency unchanged. For example, inFIG. 4(a) the channel bandwidth b_chis defined by the

boundary frequencies

401 and402. The communication device has determined, however, that only a portion of the channel bandwidth should be used, and so it transmits on a reduced bandwidth b_u(represented ascross-hatched portion403 in the figure). Such a configuration might, for example, be suitable when there are incumbents on both adjacent channels. This situation is shown inFIG. 4(b), in which there are

incumbents

404 and405 in both adjacent channels, causing the communication device to use much reducedportion406 of the available channel. As an example, with incumbents on both sides of the channel, the bandwidth used by the communication device might be divided by a factor of4 but left centred on the channel's centre frequency.

In addition to scaling the bandwidth, a further option available to the communication device is to shift the centre frequency so it is offset within the whitespace channel. An example is shown inFIG. 4(c), in which the transmitbandwidth407 has been shifted from the centre frequency of the channel to provide an additional frequency guard between the transmission and the neighbouringincumbent408. As a practical example, a communication device might halve the signal bandwidth from 5 MHz to 2.5 MHz and shift it by say 2 MHz away from the adjacent incumbent. A further option is to utilise the frequency guard band at the edges of a channel being used by a distant DTV transmitter. This is illustrated inFIG. 4(d), with the communication device using one of the two

guard bands

409,410 to avoiddistant incumbent411. In this example, the communication device usesguard band409. Using a guard band might typically give a bandwidth reduction factor of 16 (giving a 3 dB bandwidth of 312.5 kHz). The frequency offset may approach 4 MHz (with an 8 MHz channel), or may be exactly 4 MHz in the case that two adjacent channels have DTV interference well above the noise floor.

Slot Scheduling

If a terminal is subject to localised interference on a particular frequency, the controller may schedule future communications with that terminal to avoid the problematic frequency. If those future communications have yet to be scheduled, the controller can simply allocate future communications with the terminal to time slots within the frequency hopping sequence that are on frequencies other than the interfered frequency. The controller may be constrained by a time period within which a particular communication needs to be scheduled. For example, inFIG. 4 a communication with a particular terminal should occur between t₁and t₂. There are two frequencies available during this time period:frequency1 andfrequency3. So if, for example, the terminal is subject to localised interference onfrequency3, the controller may select the time slot onfrequency1 for a communication with the terminal. If there are no time slots within the predetermined time period that will occur on a non-interfered frequency, the controller may be configured to not allocate a time slot for communication with the terminal in that time period. Instead, the controller may schedule a time slot outside the predetermined time period, or may wait to schedule a time slot until the next predetermined time period within which it should communicate with that terminal.

Antenna Nulling

Another option for addressing interference is for the network to determine the direction from which an interfering signal originates and for the base station to form a null in its antenna radiation pattern in that direction. An example is illustrated inFIG. 6, which shows a base station having12 available channels.Channels1 to4 (C1-4) suffer interference from TV transmitter T_A, channels5 to8 (C5-8) from transmitter T_Band channels9 to12 (C9-12) from transmitter T_c. BS is a white space network base station and all circles marked with lowercase Ts are white space network terminals. The shaded areas represent nulls with respect to the groups of frequencies marked. While effective at combating interference, the nulls will also reject signals at their respective frequencies from wanted devices in the same direction. Therefore, in the cell shown inFIG. 6, t_Acannot communicate effectively with the base station over C1-4, t_B1and t_B2cannot communicate effectively with the base station over C5-8 and t_Ccannot communicate effectively with the base station over C9-12. t_A, t_B1, t_B2and t_Care all partially or wholly masked by the antenna nulls.

If the controller determines that a terminal is subject to antenna null masking on a particular frequency, it may schedule future communications with that terminal to avoid the problematic frequency. This may be achieved in the same way as slot scheduling to avoid an interferer (as described above). The controller selects a time slot that avoids the masked frequency.

A diagram showing the functional blocks that may be comprised within a controller is shown inFIG. 7. This figure is not intended to supersede or contradictFIG. 2. The two figures show the same controller but just from different perspectives.FIG. 2 illustrates the division of communication layers between the controller and a radio;FIG. 7 shows the functional blocks that may be implemented by the communication layers working together.

The controller ofFIG. 7 is shown generally at701. The controller comprises two interfaces with which it can communicate with the network core (702) and one or more base stations (703). The controller may communicate with the network core and the base stations via either wired or wireless links. The controller further comprises a receivingunit704 for receiving data to be communicated to the terminals by the base stations. The amount of data and any timeliness or quality of service constraints are preferably communicated by the receiving unit to thescheduling unit706, which is responsible for scheduling time slots (and thereby allocating bandwidth) to the data to be communicated. The data and the associated allocations are preferably passed to aframe generation unit705, which generates the frames to be communicated to each base station. These frames may then be passed to acontrol unit707, which passes the frames to the base stations for transmission and controls the operation of the base stations in accordance with the allocated bandwidth, appropriate data rate, mode of operation etc.

The controller may also comprise appropriate functional blocks for receiving data transmitted from the terminals to the base stations, processing that data and passing it to the core network. These are not shown inFIG. 7 for clarity, but it should be understood that suitable receiving and processing units will also form part of the controller.

The apparatus inFIG. 7 is shown illustratively as comprising a number of interconnected functional blocks. This is for illustrative purposes and is not intended to define a strict division between different parts of hardware on a chip. In practice, the controller preferably uses a microprocessor acting under software control for implementing the methods described herein. In some embodiments, the algorithms may be performed wholly or partly in hardware.

The controller, other network devices described herein and the communication network as whole may be configured to operate in accordance with a protocol for machine communications, such as Weightless or any other suitable protocol.

Although one or more embodiments of the invention have been described above with specific reference to networks configured for machine communications, it should be understood that the mechanisms described above may be advantageously implemented in any type of network.

The applicants hereby disclose in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems discloses herein, and without limitation to the scope of the claims. The applicants indicate that aspects of the present invention may consist of any such feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.