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WIRELESS COMMUNICATIONS DEVICE, METHOD AND COMPUTER PROGRAM FOR GROUPING WIRELESS COMMUNICATIONS DEVICES
Technical Field
5 The present invention relates to a method, a computer program and a wireless communications device. The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs, and more specifically relate to grouping user equipments/stations by time for purposes of accessing the wireless network.
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Background
Some wireless systems are expected to be developed such that a single access node will support a large number of users. For example, there is a working group developing the 802.11 ah wireless system that is expected to have possibly 6000 15 stations (STA) supported by a single access point (AP) (see for example document IEEE 802.11-1 l/0457r0 entitled "Potential Compromise for 802.11 ah Use Case Document" by Rolf de Vegt, Qualcomm, March 2011). This arises from a particular scenario which this new wireless local area network (WLAN) system is to support, namely a Smart Grid to Pole arrangement where the different stations are each 20 associated with an electrical distribution or transmission pole and wirelessly report various parameters of the electrical distribution system they sense. In conventional WLAN, there is a contention period during which STAs wishing to transmit contend with one another for the right to use the channel. In short, each station listens for a minimum time period and if the channel is clear it may transmit. If there is a collision 25 among two STAs, they again listen and wait that minimum time, but each also adds to that listening period a random back-off time to prevent repeated collisions. This is termed in WLAN the distributed coordination function (DCF).
It has been proposed that grouping of stations might better facilitate such a 30 high number of them associated to a single AP. Grouping also alleviates other issues such as the lack of unique association identifiers for so many stations per AP, as well
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as reducing the number of re-transmission attempts which ultimately delay delivery of the packet. This latter concern is particularly noteworthy because the number of retransmission attempts and the delay to deliver a packet has been shown to grow exponentially with the number of STAs (see for example document IEEE 802.11-5 11/101 Or 1 entitled "Supporting Large Number of STAs in 802.1 lah" by MediaTek, July 20, 2011).
There have been different proposals already for grouping stations. Document IEEE 802.11-11/I255r0 (entitled "DCF Enhancements for Large Number of STAs" 10 by Siyon Liu, CATR, September 15, 2011) outlines a static grouping in which the AP controls channel access by appropriate selection of certain parameters such as contention factor and a deferral period. Dynamic grouping addresses time-variability, in case the traffic is bursty and/or the number of sensors varies with time such as when the deployed sensors deplete their energy supply or new sensors are dropped in 15 the network. Co-owned UK patent application no. 1119210.1 entitled "Method and Apparatus for Controlling Wireless Devices" (filed November 7, 2011) outlines dynamic grouping in which a station indicates its interest in changing its group and the AP can accept or reject the request.
20 Each of the above groupings are AP based, but in certain cases STA-based grouping may be preferable. This is because the AP may know the link qualities between itself and the different stations but, unless informed by the STAs themselves (which generally is not efficient in WLAN), it cannot know the exact link qualities between the STAs, or what is the amount of interference in different parts of the 25 network. Furthermore, STAs may experience interference either from other systems sharing the same frequency or due to the overlapping basic service set (OBSS) problem which is well known in the WLAN arts. See for example document IEEE 802.11-11/108r0 (entitled "Channelization Considerations for Smart Grid" by Itron, January 2012) which details sensors, such as in the 802.1 lah scenario, which 30 experience very unpredictable patterns of interference. This interference cannot be known by the AP, but it is a quantity that can be measured by the STAs.
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Another static grouping concept outlined in document IEEE 802.11-11/I255r0 (referenced above) groups the STAs into N groups. A STA selects its group statically during the Association Request. For each group n =1,2,...,N, the AP sends in the 5 beacon two numbers, Qn and Tn. These values can be set according to the current network utilisation rate, the number of STAs in group n and other factors (such as the priority of each group). The parameter Qn is termed the contention factor and takes values in [0,1]. Before contending for the channel, each STA randomly and uniformly chooses a number rn and compares it to the value Qn. If rn < Qn, then the 10 STA can contend for the channel. Otherwise, it does not initiate the distributed coordination function DCF procedure until the deferral period Tn passes.
Summary
According to a first aspect of the present invention, there is provided a method 15 for operating a wireless communications device, the method comprising: determining from downlink signalling received from an access point a contention period allocated for each of a plurality of groups; for each of the plurality of groups, measuring interference during at least a portion of the respective group's contention period; and compiling an uplink message for sending to the access point which indicates the 20 selected group.
In an embodiment, the uplink message may be an Association frame, or it may be a data transmission in which the selected group is indicated as part of the header or payload.
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According to a second aspect of the present invention, there is provided apparatus for communicating comprising a processing system constructed and arranged to cause the apparatus at least to perform: for each of the plurality of groups, measuring interference during at least a portion of the respective group's contention 30 period; selecting a group to join based on the measured interferences; and compiling an uplink message for sending to the access point which indicates the selected group
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The processing system described above may comprise at least one processor and at least one memory including computer program code, the at least one memory and the computer program code with the at least one processor being configured to 5 cause the apparatus at least to perform as described above.
According to a third aspect of the present invention, there is provided a computer program comprising a set of instructions which, when executed on an apparatus, causes the apparatus to perform actions comprising: determining from 10 downlink signalling received from an access point a contention period allocated for each of a plurality of groups; for each of the plurality of groups, measuring interference during at least a portion of the respective group's contention period; selecting a group to join based on the measured interferences; and compiling an uplink message for sending to the access point which indicates the selected group.
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The computer program described above may be provided in a computer readable memory tangibly storing the set of instructions.
The apparatus described above may be communicating apparatus, such as a 20 station in the examples below.
Examples of embodiments of the present invention provide a way for the station groups to account for the interference and channel conditions that the stations but not the AP can see, as well as to be dynamic enough to account for changing 25 conditions that make some initial grouping no longer optimal.
Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.
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Brief Description of the Drawings
Figure 1 shows a schematic diagram illustrating three groups of stations associated to an access point and another station seeking to find which group to join in order to access the network, and is an example environment in which some 5 embodiments of these teachings may be practised to advantage;
Figure 2 shows schematically a portion of the AP's beacon which informs parameters for each group according to an exemplary embodiment of these teachings;
10 Figure 3 shows a logic flow diagram that illustrates, from the perspective of the station seeking to join a group, the operation of an example of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with the exemplary embodiments of this invention; and
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Figure 4 shows a simplified block diagram of a non-limiting example of a station seeking to join a group that is associated with an access point, and are exemplary electronic devices suitable for use in practising some example embodiments of this invention.
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Detailed Description
While the examples discussed below are in the context of an 802.1 lah type of WLAN, this is a non-limiting example only. The specific examples used in these teachings may be easily adapted for other radio access technologies (RATs) such as
25 various cellular systems operating in licensed or licence-exempt frequency bands (using carrier aggregation for example), Bluetooth personal area networks, and the like, including the specific uplink and downlink signalling detailed below. In that regard, the AP in the below examples is exemplary for a generic wireless network access node and the STAs are exemplary user equipment (UEs), which may be
30 implemented as for example automated sensor devices that may engage in machine-to-machine (M2M) type communications without direct human input.
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Exemplary embodiments according to the teachings detailed below provide a station-based grouping that solves the aforementioned problems, and in particular the fact that the AP may not know the channel conditions among the STAs, the contention 5 at different parts of the network, or the interference experienced at a given STA. Even though in these teachings the STAs decide which group to join which in a sense determines the number of STAs in a group, the AP is still the entity that maintains the number of groups and decides when different groups are scheduled and for how long.
10 Figure 1 illustrates an exemplary WLAN environment in which STAs are grouped and associated to one AP 20. Three groups are shown but there may be two or more than three, and it is only for simplicity that the grouped stations are geographically near one another; the grouping teachings herein may result in stations at opposite sides of the AP 20 being in the same group. Also, there is no limitation 15 that each group need to have the same or almost the same number of stations. At Figure 1 there is one STA 10 which is not yet associated to the AP 20. According to these teachings it will measure the per-group interference that it would experience if it were a member of those individual groups and will select a group to join that has the minimal interference. Each group has a contention period, and for at least a portion of 20 each of those group-specific contention periods (such as may be given by a timer the STA keeps), the STA 10 may observe the group-specific interference to decide which group the STA should join. In the background section above was mentioned group-specific contention factors Qn and deferral periods Tn. This is one way the group-specific DCF contention periods may be defined but there are many other ways to 25 define group-wise contention periods. Contention factors and deferral periods are used in the examples below which the STA learns from e.g. a beacon frame, but this is not limiting for how the STA determines the group-specific contention periods during which it listens for interference in order to select which group to join. Further teachings below show how the STA 10 can dynamically change groups if it does not 30 have enough transmission opportunities with its initially-chosen group or if the interference it does experience with that chosen group exceeds a threshold.
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To detail the specifics of these teachings as compared to other approaches, assume as a non-limiting example that these teachings are imposed on top of the grouping concept above in which the AP provides to any given nth group values for 5 the contention factor Qn and for the deferral period (time interval) Tn. The AP sends in the beacon an indication of the total N number of groups, and also for each nth group the values for those two parameters Qn and Tn. This is shown at Figure 2: a beacon frame having a field 202 to indicate the total number of groups N the AP 20 has decided for its network, and additional fields 204-n to give the parameters 10 "contention factor" and "deferral period" for each group. The AP 20 may include the field 202 which gives the number of groups explicitly, or the number of groups may be implicit from how many group-specific fields 204n are included. In another embodiment, the AP 20 signals at least some of this information to the station in the AP's Association Response frame. For simplicity, assume as in the background 15 section above that the contention factor Qn can take values in [0,1]. Each STA creates randomly a parameter rn that takes values also in the interval [0,1] according to some distribution. Such a distribution may be uniform but this is a non-limiting example. As noted above, this is only a non-limiting example of how the STA 10 may determine the DCF contention periods for each of the groups.
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Recognising that not all STAs will have data to transmit at the same time, what is being resolved by the grouping concept herein is whether a STA is allowed to contend for the right to use the channel. In the grouping concept, any STA will contend with only other STAs in its same group (assuming no overlap in time for 25 different groups' allowed contention periods). If there is a collision among transmissions by different STAs, they may still apply the conventional back-off procedures to ensure collisions do not necessarily repeat without departing from the grouping teachings herein.
30 So according to an exemplary embodiment of these teachings, a given STA is allowed to contend for access to the wireless channel if it belongs in group n with
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non-zero Qn, and further in which rn satisfies rn < Qn. Otherwise that station's contention for the wireless channel is deferred for a period Tn. Since it is assumed that most if not all of the STAs are operating on a finite power supply (battery, fuel cell, etc.), power savings are imposed by allowing the stations to go to a reduced 5 power state commonly referred to a sleep mode. If for a given STA its rn >Qn, then it defers its access to the radio medium for the deferral time Tn after which it can contend for channel access and go into a low power mode afterwards. If rn <Qn, then the STA picks a point in time where it will do its DCF and contend for the channel, and it may go into low power mode for the remainder of the time. Prior to the DCF, 10 the STA may also be in a low power mode.
According to one exemplary but non-limiting embodiment of these teachings, each station initially chooses a group after observing the channel and interference for a duration specified by a given timer. For example, a STA first observes the 15 interference it would experience when different groups are scheduled while the timer has not expired, and decides the group to join that has the "minimum" interference. There are a number of different ways to define minimum in this context: the minimum "average" among the observed time periods, or the group that has the minimum worst case interference as compared to all other groups, just to name a few 20 non-limiting embodiments. In this case, the STA might find multiple candidate groups that meet the minimum interference criteria and the STA can choose which one to join on a random basis. The timer can have different values ranging from zero to a maximum observing duration. The STA may report to the AP the group that it joined. The STA may report this by appending this information to the next data frame 25 that it sends to the AP, either in the header or in the payload. In the special case that the timer is set to zero and it expires the STA may instead report the group it belongs to already in the Association Request.
In another embodiment the AP makes sure that all STAs know the number of 30 groups. If a new STA joins the network, the AP informs the STA of the number of groups and their parameters. The AP may do this in the Association Response frame.
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If the number of groups changes, the AP may then broadcast this information to all the STAs, such as for example in a Beacon frame. If there is a group with no STA belonging to it, the AP removes the group from its locally stored list of groups and associated STAs and informs the STAs in the next Beacon of the new number of 5 groups. If instead a new group is added by the AP, the AP broadcasts this information by adding it in the next Beacon frame.
Each time a station transmits, it computes its collision probability in the group it belongs. A STA can obtain the collision probability in several different ways. For 10 example, the STA can compute the success rate of its transmissions. The STA can maintain a history of the success rates that it experiences in different groups. This history could be for example the latest X values per group, or for some running average. Or in another embodiment, a STA can measure the interference and from that be able to estimate or predict that its collision probability will be higher when the 15 interference is higher. This latter approach would only give some measure on the expected collision probability, and so is a bit less exact than the former approach.
In one embodiment of these teachings, a STA may decide to change its group if for example its collision probability is above some threshold for more than a certain 20 amount of time units indicated by the expiration of a timer. The units can be a certain number of slots for example. Or in another embodiment, the delay introduced by the timer (hysteresis) can be deactivated by setting the timer equal to 0. And additionally this information can be used in the next transmission opportunity to decide whether the STA will remain in or leave the group. If a STA leaves a group, then it will 25 transmit as a member of the new group it joins.
In another embodiment of these teachings, a STA may decide to change its group if it does not get enough transmission opportunities and after another timer expires. For example, if the number of transmission opportunities the STA sees in the 30 group it has joined is less than another threshold and this situation persists for a given time duration given by the expiration of another timer, then the STA will use this as a
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trigger to change its group. This can happen for example if the interference within the group becomes so high once the station has joined the group that, after sensing the channel while in the group it first selected, the STA always determines that the channel is busy. Such high interference can be due to an OBSS problem or due to 5 external interference. The transmission opportunity timer offers a delay (hysteresis), and this delay by the timer can be deactivated by setting this timer equal to zero.
In another embodiment, the new group is chosen in the same manner as during the initial group selection (find the group with minimal interference) and the STA 10 informs the AP of the STA's group change. In one embodiment, the STA informs of its group change in its next data transmission.
In another embodiment, the aforementioned thresholds can be specified by the STA and may depend for example on the QoS (quality of service) requirements of the 15 STA. For example:
• If a STA has high QoS requirements then the first threshold is small to indicate that the STA does not tolerate many collisions and in this case the STA should seek a new group.
• If a STA needs to have a high number of transmission opportunities, such 20 as to increase its data rate, the second threshold is set to a large value. In this case the STA may stay in its current group if the transmission opportunities it receives are at least as many as the second threshold. If the transmission opportunities are less than the second threshold then the STA may not receive enough transmission opportunities and in this case should 25 then seek a new group.
In another embodiment, the aforementioned thresholds can be specified by the AP and may depend on the number of STAs associated with the AP and associated with a given group and also may depend on the expected traffic characteristics. For 30 example:
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• The number of STAs per group and the total number of STAs associated with a given group determine the expected collision probabilities.
• A STA could then additionally inform the AP of its traffic characteristics to assist this measurement. For example, this information can be sent by
5 the STA in its Association Request frame, or as a different information field that the STA sends along with its data transmissions.
The process of a STA changing its group may in some instances have an oscillating behaviour, for example as more and more stations associate to the AP or 10 when stations drop out (for example, drop offline due to depleting their power source). However, eventually a steady state should be reached unless no group can "sustain" a probability of collision less than what is specified by the first threshold, or unless the transmission opportunities are always less than the second threshold.
15 In that case, in another embodiment of this invention the threshold values may be adjusted by any of the following options:
• The AP or the STAs can increase the first threshold value which is related to its QoS.
20 o The first threshold can be increased, for example beginning with the
STAs that have the highest QoS requirement (smaller threshold) or lowest QoS requirement (larger threshold).
o The AP can send the updated threshold values to the affected STAs, such as in Beacon messages.
25 o The STAs can send their updated threshold values, such as by piggybacking those values in the STA's data packets.
• The STAs can decrease the second threshold value which is related to the number of transmission opportunities.
30 o The second threshold can be decreased for example beginning from the
STAs that have the highest transmission opportunity requirement
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(largest threshold) or lowest transmission opportunity requirement (lowest threshold).
o STAs may send their updated threshold values to the AP, for example by piggybacking the new value in the STA's data packets.
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Changing the above thresholds can help stabilise oscillating behaviour from STAs changing the group to which they are associated. Further to stabilise this group switching, the AP 20 can increase the number of groups and advertise the new total (explicitly as a new total N or implicitly by sending the new group's parameters Q and 10 T) to all the stations, such as for example in a beacon frame (see Figure 2). Or if an individual STA is seeing itself switch groups too frequently it may request a new group from the AP rather than choose itself a new group to join. Or in another embodiment the above-mentioned delay (hysteresis) timer may be used to prevent the STA from changing groups too frequently, so that for a given STA changing groups is 15 only allowed once the delay timer has expired regardless of QoS or number of transmission opportunities. Such a delay timer may be implemented to take effect only after a first group change under a given AP 20.
From the STAs reporting which group they have joined the AP is aware of the 20 number of STAs associated in each group. But the STAs may change groups as detailed above. Accordingly, below are described examples of ways of how the AP keeps this information up to date despite the static or dynamic grouping aspects of these teachings. In the above examples, the dynamic grouping includes re-evaluating the grouping parameters due to traffic changes and new stations associating to or 25 dropping their association with a given AP 20.
In one embodiment for the case of dynamic grouping, or during oscillation periods, when a station transmits a packet to the AP the STA appends its group information (either in the header or in the payload) only if the AP is not already aware 30 of the station's current group. For example the station will append this group information if it is the first time the station has selected this group to join, or if the
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station's group has changed. In the former case the station may instead inform the AP of the first group it has selected in an Association Frame, if in fact the station has joined the AP's network for the first time.
5 In another embodiment in the case of static grouping, following are some non-
limiting examples of how the AP can keep its information on group-performance current in order to know whether or not STAs are changing groups too frequently, and know whether it needs to update threshold values and/or add a new group.
10 1. If groups are formed such that Qn = 1 for some n and Qm = 0 for every other m ± n then the AP can observe the groups indirectly based on the STA identities of different receptions at different time instants. This is because the AP knows the time periods where each group is having Qn = 1.
15 2. If groups are formed such that Qn is an arbitrary number greater than zero for some n and Qm = 0 for every other m ± n, then the AP will have to observe the behaviour over multiple intervals or use for a few slots instead Qn = 1 and Qm = 0 for all the other groups m as in bullet #1 above. This is because here there is still a non-zero probability that a STA does not 20 contend for the channel if its parameter rn > Qn.
3. If groups are formed such that Qn, Qm > 0 for some n, m with m^n, then the AP can at the beginning try to learn the groups. This can be done if the AP sends non-overlapping groups (as in case 1) and learns to which group 25 each STA belongs. For example, in the case of 3 groups with (Qi, Q2, Q3)
= (1, 0.75, 0.5), the AP for a few time slots can use instead (Qi, Q2, Q3) = (1, 0, 0), (Qi, Q2, Q3) = (0, 0.1, 0), and (Qi, Q2, Q3) = (0, 0, 1) until it learns which STAs belong in each group and then use the original grouping.
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Any given implementation may of course use a mixture of the above static and dynamic cases.
As shown at Figure 2, the AP can send the number of groups in a Beacon 5 Frame or in the Association response messages to the individual stations when they first associate to the AP. When the number of groups changes, the AP lets the associated STAs know of this change, for example by sending the new value in a broadcast message such as the next Beacon Frame.
10 In the case of dynamic groups and during oscillation periods, the stations can add a new field (such as in the header but alternatively in the payload) of their uplink data transmissions to indicate their new group number to the AP. So generally the STAs can piggyback their individual grouping information to their data packets (in the header or as part of the payload) and thus do not need to send additional packets to 15 report this group information, thereby avoiding unnecessary contention.
One technical advantage of these teachings is that they enable self-configurability of stations into groups. Another technical effect is that this mitigates interference problems at the stations because stations can choose to join the group 20 with the least interference.
Figure 3 is a logic flow diagram which summarises some example embodiments of the invention. Figure 3 is worded to describe from the perspective of the station (or one or more components thereof) that is finding a group to join when 25 first associating to the AP, or when seeking to change to a different group from the one with which it is currently associated. Figure 3 may be considered to illustrate the operation of an example of a method for operating a wireless communications device, and a result of execution of a computer program stored in a computer readable memory, and a specific manner in which components of an electronic device are 30 configured to cause that electronic device to operate, whether such an electronic
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device is the station, or one or more components therefore such as a modem, chipset, or the like.
Such blocks and the functions they represent are non-limiting examples, and 5 may be practised in various components such as integrated circuit chips and modules, and the exemplary embodiments of this invention may be realised in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband 10 circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.
Such circuit/circuitry embodiments include any of the following: (a) hardware-only circuit implementations (such as implementations in only analog 15 and/or digital circuitry) and (b) combinations of circuits and software (and/or firmware), such as: (i) a combination of processor(s) or (ii) portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone/UE, to perform the various functions summarised at Figure 3) and (c) circuits, such as a 20 microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple 25 processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" also covers, for example, a baseband integrated circuit or applications processor integrated circuit for a mobile phone/user equipment or a similar integrated circuit in a server, a cellular network device, or other network device.
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At block 302 the station determines from downlink signalling received from an access point a contention period allocated for each of a plurality of groups. As noted above, in some embodiments the AP will inform the station of the information at block 302 in a Beacon frame, or it may give some or all of it in the Association 5 Response frame/message. In the non-limiting examples above the STA determines the contention period allocated for each of the plurality of groups from at least a group-specific contention factor Q and a group-specific deferral period T that the STA 10 receives in the downlink signalling from the AP 20. The term access point is not limited to WLAN but encompasses access nodes of other networks as noted above.
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Then at block 304 and for each of the plurality of groups, the station measures the individual per-group interference during at least a portion of the respective group's contention period (for example, for the duration of a timer). At block 306 the station selects a group to join based on the measured interferences. While not 15 limiting, the group that the station selects at block 306 is the group having the least measured interference as measured at block 304, and above are detailed two examples of how to define that minimal interference on which the station bases its group selection decision: an average interference over a duration given by a timer and a worst case interference over a duration given by a timer.
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Then at block 308 the station compiles an uplink message to be sent to the access point which indicates the selected group. As detailed above, in different embodiments the STA's indication of the selected group may be a part of the header or payload of the station's next data transmission, or it may be in the station's 25 Association frame/message.
Once the station is in a group, it may choose to select another group for various reasons. As detailed above, the station may monitor its collision probability and select a different group to join if the monitored collision probability exceeds a 30 threshold. In this case, the station repeats the process of Figure 3 for selecting that new group. Similarly the station may select a different group to join if the station
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finds the number of transmission opportunities for its current group is less than a minimum threshold, where such a threshold may depend on a quality of service QoS requirement of the station and/or a total number of stations associated to the same access point. These two thresholds may be combined onto one embodiment such that 5 the station monitors the collision probability for a first timer duration and a number of transmission opportunities for a second timer duration, and selects a different group if the collision probability for the first timer duration exceeds a first threshold while also the number of transmission opportunities for the second timer duration is less than a second threshold. More generally, these timers can be referred to as durations of time, 10 since the duration might be a simple count of a predetermined number of radio sub frames or slots rather than a dedicated timer as such. These two thresholds may be received by the station in a beacon frame for example, or if the station adjusts the thresholds to avoid too-frequent group changes the station may send its updated threshold values to the access point such as in its next data transmission piggybacked 15 with data.
As noted above, the station's selection of a new group to join may be directed by the access point, such as in the case when the station requests the access point which new group it should join. Or if the access point makes a new group and 20 indicates that to all the stations, the station seeking to change groups may consider that in its own self-selection of its new group to join.
Reference is now made to Figure 4 for illustrating a simplified block diagram of examples of various electronic devices and apparatus that are suitable for use in 25 practising some example embodiments of this invention. In Figure 4, a wireless network represented by the AP 20, or more generally an access node if these teachings are implemented in other than a WLAN environment, is adapted for communication over a wireless link 15 with an apparatus such as a station 10 or more generally a portable radio device such as a user equipment UE. The network may also provide 30 connectivity via data/control path 30 with a broader network (e.g. a cellular network
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and/or a publicly switched telephone network PSTN and/or a data communications network/Internet).
The station 10 includes processing means such as at least one data processor 5 (DP) 10A, storing means such as at least one computer-readable memory (MEM) 10B storing at least one computer program (PROG) 10C, communicating means such as a transmitter TX 10D and a receiver RX 10E for bidirectional wireless communications with the network access point 20 via one or more antennas 10F. Also stored in the MEM 10B at reference number 10G is the station's rules for selecting which group to
10 join based on per-group interference it measures, as is detailed above with specificity. Another STA is illustrated to represent the other groups shown more particularly at Figure 1, and the station 10 measures this interference by observing wireless signalling.
15 The access point 20 also includes processing means such as at least one data processor (DP) 20A, storing means such as at least one computer-readable memory (MEM) 20B storing at least one computer program (PROG) 20C, and communicating means such as a transmitter TX 20D and a receiver RX 20E for bidirectional wireless communications with the station 10 via one or more antennas 20F.
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While not particularly illustrated for the station 10 or AP 20, those devices are also assumed to include as part of their wireless communicating means a modem which may be inbuilt on an RF front end chip within those devices 10, 20 and which also carries the TX 10D/20D and the RX 10E/20E.
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At least one of the PROGs 10C/10G in the station 10 is assumed to include program instructions that, when executed by the associated DP 10A, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above particularly with respect to Figure 3. The AP 20 also has software
30 stored in its MEM 20B to implement certain aspects of these teachings as detailed above. In this regard, the exemplary embodiments of this invention may be
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implemented at least in part by computer software stored on the MEM 10B, 20B which is executable by the DP 10A of the station 10 and/or by the DP 20A of the access point 20, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these 5 aspects of the invention may not be the entire station 10 or AP 20, but exemplary embodiments may be implemented by one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, modem, system-on-a-chip SOC or an application specific integrated circuit ASIC.
10 In general, the various embodiments of the station 10 can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to user equipments, cellular telephones, navigation devices, laptop/palmtop/tablet computers, digital cameras and Internet appliances, as well as machine-to-machine devices which operate without direct user 15 action.
Various embodiments of the computer readable MEMs 10B, 20B include any data storage technology type which is suitable to the local technical environment, including but not limited to semiconductor based memory devices, magnetic memory 20 devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DPs 10A, 20A include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), and multi-core processors.
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Some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features. The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in 30 limitation thereof.
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The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with 5 one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.
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