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Title of the Invention
WIRELESS COMMUNICATION SYSTEMS
Field of the Invention
The present invention relates to wireless communication systems, more
particularly packet-based systems in which a base station (BS) communicates with
multiple fixed or mobile subscriber stations (SS).
Background of the Invention
Recently, various standards have been developed for data communication over
broadband wireless links. One such standard is set out in the IEEE 802.16
specifications and is commonly known as WiMAX. The specifications include IEEE
802.16-2004, primarily intended for systems having fixed subscriber stations, and an
enhanced specification IEEE 802.16e-2005 which among other things provides for
mobile subscriber stations. In the following description, the term subscriber station
(SS) applies to both fixed and mobile stations (SS/MS).
The entire content of IEEE Std 802.16-2004 "Air Interface for Fixed Broadband
Wireless Access Systems" is hereby incorporated by reference. IEEE 802.16
envisages single-hop systems in which the subscriber station communicate directly
with a base station within range, the range of a base station defining a "cell". By
deploying multiple base stations at suitable positions within a given geographical area,
a contiguous group of cells can be created to form a wide-area network. In this
specification, the terms "network" and "system" will be used equivalently.
In systems of the above type, data is communicated by exchange of packets
between the subscriber stations and base station whilst a connection (also called
"transport connection") is maintained between them. The direction of transmission of

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packets from the subscriber station to the base station is called the uplink, and the
direction from the base station to the subscriber station is the downlink. The packets
have a defined format which follows a layered protocol applied to the system and its
component radio devices. Protocol layers relevant to packets as such are the so-called
physical layer (PHY) and media access layer (MAC). In the IEEE 802.16-2004
specification, these protocol layers form a protocol "stack" as shown in Fig. 1.
Incidentally, Fig. 1 also shows interfaces between protocol layers in the form of service
access points (SAPs), though these are not relevant to the present invention.
The media access layer is responsible for handling network access, bandwidth
allocation, and maintaining connections. Various physical layer implementations are
possible in a IEEE 802.16 network, depending on the available frequency range and
application; for example, both a time division duplex (TDD) mode - in which uplink and
downlink transmissions are separated in time but may share the same frequency - and
a frequency division duplex (FDD) mode - where uplink and downlink transmissions
can occur at the same time but on different frequencies - are possible. A connection
between a base station and subscriber station (more precisely, between MAC layers in
those devices - so-called peer entities) is assigned a connection ID (CID) and the base
station keeps track of CIDs for managing its active connections. Data is exchanged
between the MAC peer entities, in other words, between the subscriber station and
base station, in units of a protocol data unit (PDU), the PDU being conveyed across the
PHY layer using a number of slots.
The concept of quality of service (QoS) is employed in wireless communication
systems for allowing a wide range of services to be provided. During communication
with a subscriber station, the base station allocates a QoS level depending on the type
of service requested by the subscriber station and available bandwidth, bearing in mind
that the base station typically will be communicating with several subscriber stations
simultaneously. The QoS is allocated first during a network entry procedure at the time

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the subscriber station joins the network, and may be modified subsequently by the
subscriber station making a request to the base station whilst the connection is
maintained.
The relationship between QoS and CID/SFID is illustrated in Figure 2. For ease
of understanding Fig. 2, it is noted that "service flow" refers to transmission of data in a
given direction (uplink or downlink) on a connection having a particular QoS. The QoS
of the connection is defined by a service flow identifier (SFID) which has a one-to-one
relationship to the connection ID.
For example, the IEEE 802.16 specification provides four QoS classes or levels
as follows:
(i) Unsolicited Grant Service (UGS):
This service supports real-time data streams consisting of fixed-size packets
issued at periodic intervals, such as voice calls (VoIP).
(ii) Real-time Polling Service (rtPS):
This supports real-time data streams consisting of variable-sized packets issued
at periodic intervals, such as MPEG video.
(iii) Non-real-time Polling Service (nrtPS):
A service level intended to support delay-tolerant data streams consisting of
variable-sized packets for which a minimum transfer rate is needed, such as FTP (File
Transfer Protocol).
(iv) Best Effort (BE)
This lowest service level is for data streams with no particular service
requirements. Packets are handled as and when bandwidth is available.
However efficient the communication scheme employed in terms of use/re-use of
available frequencies, since several subscriber stations typically access the same base
station at the same time there is the possibility of "collision" between bandwidth
requests among the subscriber stations. A contention-based scheme is therefore

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adopted in which the QoS is used to allocate bandwidth among the connected
subscriber stations.
As already mentioned, packets involve both PHY and MAC protocol layers. More
particularly, Figure 3 shows a packet format having two parts, a PHY header and a
MAC PDU. The MAC PDU in turn consists of a MAC header, an optional payload, and
optional error correction code (cyclic redundancy code or CRC). Figure 4 shows a
generic MAC header format as specified in IEEE 802.16-2004, including a 16-bit CID.
In single hop systems as envisaged in IEEE 802.16, each subscriber station (SS)
will request bandwidth directly from the base station (BS), thus sharing the access to a
common base station. If the SS has not got any bandwidth, in the network entry and
initialization stage, it will use a CDMA ranging code to request bandwidth. The BS
handles these requests on a contention basis as already mentioned. Once the SS gets
some initial bandwidth, it may subsequently use a stand-alone bandwidth request MAC
(Media Access Control) header or Piggyback request to further request bandwidth.
The Piggyback bandwidth request shall always be incremental. The stand-alone
request can be incremental or aggregate.
The service flow between SS and BS can be created and activated during
network entry procedure or by dynamic service flow procedure. A service flow ID
(SFID) will be assigned to each existing service flow, and each service flow is also
associated to a specific QoS demand. A service flow has at least an SFID and an
associated direction. The connection ID (CID) of the transport connection exists only
when the service flow is admitted or active. The relationship between SFID and
transport CID is unique, which means an SFID shall never be associated with more
than one transport ID, and a transport CID shall never be associated with more than
one SFID.

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The CID will be enclosed with the bandwidth request, thus the BS can know which
SS requests bandwidth, and what is the associated QoS demand.
Recently, efforts are being made to extend IEEE 802.16 to multi-hop
configurations in which traffic between BS and SS is routed via one or more relay
stations (RS), rather than being transmitted directly. Figure 5 shows an example of
such a configuration having two relay stations labelled RS1# and RS2#. If the network
is modified to support relaying functionality as shown in Fig. 5, normally, the relay
station (RS) will relay the band requests (BRs) of all SSs or RSs within its coverage to
the BS.
The problem with this bandwidth request protocol is that BS will face many
bandwidth request messages, which means a lot of bandwidth between BS and RS1#,
and contention is likely to be needed between these bandwidth requests. Especially,
when the number of hops is more than two, the number of bandwidth requests between
BS and its closest RS, such as RS1# in Fig. 5, will be accumulated, thus more
bandwidth will be used for signalling overhead. This is a particular problem since in
general, uplink bandwidth is more constrained than downlink bandwidth. Moreover,
when a CDMA ranging code is used for bandwidth request, the increased number of
bandwidth requests received by the BS will increase the collision probability of the
transmission of the broadcasted CDMA codes.
On the other hand, in non-transparent or distributed relay systems, an RS may
deal with the burst dimensioning, bandwidth allocation, and packet scheduling by itself.
These operations are also relevant to bandwidth allocation for the radio devices within
its cell. Therefore, it is possible for an RS to be involved in the bandwidth request
procedure.

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Summary of the Invention
According to a first aspect of the present invention, there is provided a wireless
communication method in which subscriber stations are each operable for
communication with a base station, the base station being capable of performing
simultaneous communications with a number of subscriber stations by allocating an
available capacity among the subscriber stations, the subscriber stations being
required to issue capacity requests in order to obtain and/or maintain a connection with
the base station, and communications between the subscriber stations and the base
station being performed partly or wholly through at least one relay station, the method
comprising steps of:
in the relay station, detecting capacity requests issued from a plurality of the
subscriber stations, using the detected requests to form at least one combined capacity
request, and transmitting the combined capacity request to the base station;
in the base station, responding to the combined capacity request by reserving
capacity for said plurality of subscriber stations; and
in the relay station or in the base station, allocating the reserved capacity among
the plurality of subscriber stations.
Other aspects of the invention provide a wireless communication system, a relay
station, a base station, and a computer program as set forth in the accompanying
independent claims.
Brief Description of the Drawings
Reference is made, by way of example only, to the accompanying drawings in
which:
Figure 1 shows protocol layering in accordance with IEEE 802.16;

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Figure 2 shows the relationship between CID, SFID and QoS in an IEEE 802.16
network;
Figure 3 shows a packet format capable of being used in an IEEE 802.16
network;
Figure 4 shows a generic MAC header of a packet as set forth in the IEEE
802.16 specification;
Figure 5 illustrates a simple bandwidth request protocol in a multi-hop wireless
communication system;
Figure 6 illustrates the bandwidth request (BR) protocol employed in the present
invention;
Figure 7 is a flowchart of processing of initial bandwidth requests in a RS;
Figure 8 is a flowchart of processing of further bandwidth requests in the RS;
Figure 9 shows a first message format of a combined instant BR in accordance
with the present invention; and
Figure 10 shows a second message format of a combined instant BR in
accordance with the present invention.
Detailed Description
An embodiment of the present invention will now be described with reference to
Fig.s 6-10, using an IEEE 802.16 network as an example.
In this invention, an algorithm is proposed by which the relay station can classify
and combine the bandwidth requests from the subscriber stations (or any other relay
station) within its cell, and submit the combined bandwidth requests to the base station,
thus decreasing the overhead and collision of bandwidth request messages. This is

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schematically shown in Fig. 6, in which the subscriber stations are mobile stations
denoted by MS. The thick arrow in Fig.6 represents a combined BR formed in the RS
and replacing the multiple parallel BRs relayed by the RS in Fig. 5. As already
mentioned, bandwidth requests (BRs) fall into two categories, initial BRs and further
BRs, and these are treated differently in the present embodiment.
1. Initial Bandwidth Request
In the network entry and initialization stage, each SS within range of an RS will
use contention-based CDMA ranging for requesting initial bandwidth. When the RS
detects these CDMA codes, it can send a different CDMA code to the BS to request
bandwidth for these SSs, rather than simply relaying two detected CDMA codes to BS,
thus saving bandwidth and decreasing the collision probability of the CDMA code
transmission surround BS. Alternatively, the RS can use a stand-alone bandwidth
request MAC header to request bandwidth for these SSs. This procedure is shown in
the flowchart of Fig.7.
2. Further Bandwidth Request
As explained above, once the SS gets some initial bandwidth, it may
subsequently use a stand-alone bandwidth request MAC (Media Access Control)
header or Piggyback request to further request bandwidth. In this stage, the RS
classifies the received standalone or Piggyback BRs into "Instant BR" (IBR), and "Non-
instant BR" (NIBR). The IBRs will be combined and sent to BS by RS as soon as
possible. The NIBRs will be combined and sent by periodical aggregate BR by RS.
The procedure in the relay station for processing such further BRs is shown in
Fig. 8.

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The first stage is for the RS to receive BRs. Then RS shall identify the QoS
parameters relating to the service flow of the corresponding bandwidth request. For
example, an RS can index the connection ID (CID) enclosed within the BRs to find the
QoS demands. To allow RS to learn the QoS demands of service flows, during the
service connection request period, BS has to tell the RS the information of the approved
service flows. Alternatively, an RS can "listen in" to the information exchanged during
the service connection request period to obtain the QoS associated with the CID, and
the relationship between service flow and CID.
In light of QoS demands, the received BRs will be classified into two categories,
IBR, and NIBR, by RS. For example, the BRs relevant to Unsolicited Grant Service
(UGC), and Real-time Polling Service (rtPS) may be identified as IBR. The BRs for
Best Effort (BE), and Non-real-time Polling Service (nrtPS) may be classified as NIBR.
If the number of received IBRs is one, then RS records the amount of the
bandwidth requested by this IBR, and simply sends this IBR to BS as soon as possible.
This IBR can be incremental or aggregate. The RS will keep the original CID for this
IBR.
If the number of received IBRs in the current frame is more than one, then RS will
combine these IBRs to one BR, called combined IBR, and send this combined BR to
BS as soon as possible. In this case, the RS will also record the aggregation of the
requested bandwidth of all IBRs. This combined IBR can be incremental or aggregate.
A first possible message format of a combined IBR is shown in Fig. 9 (Format A).
The details of this control message format are listed in Table 1 below.

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Table 1: Bandwidth request control message format A of a combined IBR

Name Description
Head Type of the message, etc.
Amount of the Nth IBR The number of units, such as bytes, ofuplink bandwidth requested by the NthIBR
Other information of the Nth IBR It is optional. It could be the relevanttransmission power, and CINR etc.
Connection ID of the Nth IBR Connection ID
Check sequence To check the received message, such asCRC sequence
To decrease the size of the control message of a combined IBR, the RS can use
the message format shown in Fig. 10 (Format B). The details of this control message
are listed in Table 2. When using this message format, the RS will use one of its
existing (previously configured) CIDs, which is associated with all CIDs used by its SS,
or MS, and RS. The BS will know that the bandwidth request enclosed with this CID is
used for the SSs and any other RSs connected to the RS.

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Table 2: Bandwidth request message format B of a combined IBR

Name Description
Head Type of the message, etc.
The aggregation of all IBR The total number of units, such as bytes,of uplink bandwidth requested by the allIBRs
Other information It is optional. It could be the relevanttransmission power, and CINR etc.
Connection ID RS can apply an existing connection ID,which is associated with all the CIDsbelonging to all radio devices connectedwith itself.
Check sequence To check the received message, such asCRC sequence
After processing the IBRs, the RS will record the aggregation of the requested
5 bandwidth by all NIBRs. When the timer for periodical RS bandwidth request is expired,
the RS will work out the aggregation of the bandwidth needed for its uplink
transmission, and transmit an aggregate bandwidth request to the BS. The RS can use
the "message format B" in figure 10 for this bandwidth request. Therefore, an existing
CID is needed by RS to associate all CIDs connected to itself.

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The period of the aggregate bandwidth request may be a function of the QoS of
the services relating to NIBRs, and of the link quality.
In response to the BR from the RS, the BS performs necessary processing for
allocation of bandwidth. In the case of a format A bandwidth request (Fig. 9), the
amounts of bandwidth (incremental or aggregate) required by the individual SSs (or
other RSs) is contained in the request from the RS. In this case the BS must allocate
bandwidth on an individual basis and notify the RS accordingly, the RS then simply
noting the amounts so notified. In the case of a format B bandwidth request (Fig. 10),
the BS grants the requested amount (if possible; otherwise a lesser amount) and
informs the RS accordingly. It is then up to the RS to allocate the granted bandwidth by
dividing up the granted amount appropriately among the requesting SSs/RSs, in
dependence upon their QoS requirements.
Although the above description concerns the processing in a single RS and BS,
other RSs may be present in the network. In this case, in relation to each other RS, the
first RS may act like the BS in the above explanation. Each other RS will serve its own
set of SSs and combine the BRs received from those SSs in the same manner as
explained above for the first RS.
In summary, embodiments of the present invention may provide the following
features:
- -Defining a protocol for an RS to process the received bandwidth requests.
- -Minimising the control message overhead by classifying and combining
received bandwidth requests in RS.
- -Decreasing the collision probability for the contention style bandwidth request.

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- The method proposed can be used for other message relaying, thus
achieving the above benefits.
Embodiments of the present invention may be implemented in hardware, or as
software modules running on one or more processors, or on a combination thereof.
That is, those skilled in the art will appreciate that a microprocessor or digital signal
processor (DSP) may be used in practice to implement some or all of the functionality of
the RS or BS in the present invention. It is also possible to provide each SS with some
or all of the functionality of the RS. The invention may also be embodied as one or
more device or apparatus programs (e.g. computer programs and computer program
products) for carrying out part or all of any of the methods described herein. Such
programs embodying the present invention may be stored on computer-readable
media, or could, for example, be in the form of one or more signals. Such signals may
be data signals downloadable from an Internet website, or provided on a carrier signal,
or in any other form.

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CLAIMS
1. A wireless communication method in which subscriber stations are each operable
for communication with a base station, the base station being capable of performing
simultaneous communications with a number of subscriber stations by allocating an
available capacity among the subscriber stations, the subscriber stations being
required to issue capacity requests in order to obtain and/or maintain a connection with
the base station, and communications between the subscriber stations and the base
station being performed partly or wholly through at least one relay station, the method
comprising steps of:
in the relay station, detecting capacity requests issued from a plurality of the
subscriber stations, using the detected requests to form at least one combined capacity
request, and transmitting the combined capacity request to the base station;
in the base station, responding to the combined capacity request by reserving
capacity for said plurality of subscriber stations; and
in the relay station or in the base station, allocating the reserved capacity among
the plurality of subscriber stations.
2. The method according to claim 1, wherein each subscriber station issues a
capacity request as part of a network entry procedure to obtain a connection with the
base station.
3. The method according to claim 1 or 2, wherein at least some subscriber stations
issue a capacity request during communication with the base station to maintain or
change an existing connection with the base station.

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4. The method according to claim 2 or 3, wherein the capacity request is a request
for an absolute amount of capacity.
5. The method according to claim 3, wherein the capacity request is a request for
an incremental amount of capacity.
6. The method according to any preceding claim wherein each capacity request is a
bandwidth request for allocation of bandwidth from the base station.
7. The method according to claim 6, wherein the bandwidth request is an initial
bandwidth request in the form of a CDMA ranging code.
8. The method according to claim 7, wherein the relay station transmits the
combined bandwidth request in the form of a CDMA code.
9. The method according to claim 6, wherein the bandwidth request is a further
bandwidth request in the form of a stand alone media access control header.
10. The method according to claim 6, 7 or 9 wherein the relay station transmits the
combined bandwidth request in the form of a stand alone media access control header.
11. The method according to any preceding claim, wherein communication is
performed through exchange of packets and the relay station transmits the combined
capacity request in a medium access control layer header of such a packet.
12. The method according to any preceding claim, wherein the combined capacity
request includes details of individual capacity requests detected in said detecting step.

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13. The method according to claim 12, wherein each connection between a
subscriber stations and the base station has a connection ID, and said details include
connection IDs corresponding to the detected capacity requests.
14. The method according to any of claims 1 to 11, wherein the combined capacity
request aggregates the amounts of capacity contained in the detected capacity
requests without including details of the individual capacity requests.
15. The method according to claim 14, wherein the connection between the relay
station and the base station has a connection ID, and said combined capacity request
includes said connection ID.
16. The method according to any preceding claim, further comprising the step, in the
relay station, of classifying the detected capacity requests based on properties thereof.
17. The method according to claim 16 wherein the relay station classifies the
detected capacity requests into urgent and non-urgent requests.
18. The method according to claim 17 wherein separate combined capacity requests
are formed using the urgent and the non-urgent requests respectively.
19. The method according to claim 18 wherein said step of transmitting the combined
capacity request includes immediately transmitting a combined capacity request
formed using urgent requests, whilst delaying transmission of a combined capacity
request formed using non-urgent requests.

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20. The method according to claim 19 wherein the relay station waits for a
predetermined time period to elapse before transmitting the combined capacity request
formed from non-urgent requests.
21. The method according to any of claims 16 to 20, wherein each connection
between a subscriber station and the base station is assigned one of a plurality of
levels of quality-of-service (QoS), and said classifying step is performed based on the
QoS.
22. The method according to claim 21, wherein each connection between a
subscriber station and the base station has a connection ID with which QoS information
is associated, the relay station obtaining the QoS based on the connection ID.
23. The method according to claims 2 and 22 combined, wherein the base station
assigns the QoS during the network entry procedure and informs the base station of
the QoS for each connection.
24. The method according to any preceding claim, wherein the system comprises at
least one further relay station in communication with said relay station, the further relay
station performing the same steps as said relay station in relation to further subscriber
stations with said relay station acting as its base station, said relay station detecting a
capacity request from said further relay station and using that capacity request in
forming said combined capacity request.
25. The method according to any preceding claim wherein one or more of the
subscriber stations are mobile stations.

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26. A wireless communication system in which subscriber stations are each operable
for communication with a base station, the base station being capable of performing
simultaneous communications with a number of subscriber stations by allocating an
available capacity among the subscriber stations, the subscriber stations being
required to issue capacity requests in order to obtain and/or maintain a connection with
the base station, and communications between the subscriber stations and the base
station being performed partly or wholly through at least one relay station, wherein:
the relay station comprises means for detecting capacity requests issued from a
plurality of the subscriber stations, for using the detected requests to form at least one
combined capacity request, and for transmitting the combined capacity request to the
base station;
the base station includes means for responding to the combined capacity request
by reserving capacity for said plurality of subscriber stations; and
the relay station or the base station includes means for allocating the reserved
capacity among the plurality of subscriber stations.
27. A relay station for use in a wireless communication system in which subscriber
stations are each operable for communication with a base station, the base station
being capable of performing simultaneous communications with a number of subscriber
stations by allocating an available capacity among the subscriber stations, the
subscriber stations being required to issue capacity requests in order to obtain and/or
maintain a connection with the base station, and communications between the
subscriber stations and the base station being performed partly or wholly through the
relay station, wherein the relay station comprises:

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detecting means for detecting capacity requests issued from a plurality of the
subscriber stations;
combining means for using the detected requests to form at least one combined
capacity request;
transmitting means for transmitting the combined capacity request to the base
station; and
allocating means, responsive to a notification of reserved capacity received from
the base station, to allocate the reserved capacity among the plurality of subscriber
stations.
28. The relay station according to claim 27, wherein communication in said system is
performed through exchange of packets and the transmitting means is arranged to
transmit the combined capacity request in a medium access control layer header of
such a packet.
29. The relay station according to claim 27 or 28, wherein the combined capacity
request includes details of individual capacity requests detected by said detecting
means.
30. The relay station according to claim 29, wherein the notification of reserved
capacity received from the base station includes information on an individual amount of
capacity for each subscriber station to be allocated by the allocating means.
31. The relay station according to claim 27 or 28, wherein the combined capacity
request does not include details of individual capacity requests detected by said
detecting means.

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32. The relay station according to claim 31, wherein the notification of reserved
capacity includes an aggregate amount of capacity and the allocating means is
arranged to partition the reserved capacity among the plurality of subscriber stations.
33. The relay station according to any of claims 27 to 32, wherein the combining
means includes means for classifying the detected capacity requests based on
properties thereof.
34. The relay station according to claim 33 wherein the classifying means is operable
to classify the detected capacity requests into urgent and non-urgent requests.
35. The relay station according to claim 34 wherein the combining means is arranged
to form separate combined capacity requests using the urgent and the non-urgent
requests respectively.
36. The relay station according to claim 35 wherein the transmitting means is
arranged for immediately transmitting a combined capacity request formed using
urgent requests, whilst delaying transmission of a combined capacity request formed
using non-urgent requests.
37. The relay station according to claim 36 wherein the transmitting means is
arranged to wait for a predetermined time period to elapse before transmitting the
combined capacity request formed from non-urgent requests.
38. The relay station according to any of claims 33 to 37, wherein each connection
between a subscriber station and the base station is assigned one of a plurality of

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levels of quality-of-service (QoS), and the classifying means performs said classifying
based on the QoS.
39. The relay station according to claim 38, wherein each connection between a
subscriber station and the base station has a connection ID with which QoS information
is associated, and said classifying means is arranged to obtain the QoS based on the
connection ID.
40. The relay station according to any of claims 27 to 39, wherein the detecting
means is arranged to detect a capacity request from at least one further relay station,
the further relay station performing the same role as said relay station in relation to
further subscriber stations, and said combining means is arranged to use that capacity
request in forming said combined capacity request.
41. A computer program which, when executed by a relay station of a wireless
communication system, provides the relay station according to any of claims 27 to 40.
42. A base station for use in a wireless communication system in which subscriber
stations are each operable for communication with the base station, the base station
being capable of performing simultaneous communications with a number of subscriber
stations by allocating an available capacity among the subscriber stations, the
subscriber stations being required to issue capacity requests in order to obtain and/or
maintain a connection with the base station, and communications between the
subscriber stations and the base station being performed partly or wholly through at
least one relay station, wherein the relay station detects capacity requests issued from
a plurality of the subscriber stations and transmits a combined capacity request to the
base station; the base station comprising:

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decoding means for decoding the combined capacity request received from the
relay station;
capacity reserving means, responsive to results of said decoding to reserve
capacity for the plurality of subscriber stations; and
transmitting means for informing the relay station of the reserved capacity.
43 The base station according to claim 42, wherein communication in said system is
performed through exchange of packets and the decoding means is arranged to
decode the combined bandwidth request in a medium access control layer header of
such a packet.
44. The base station according to claim 42 or 43, wherein the decoding means is
arranged to extract details of individual capacity requests made by the subscriber
stations and contained in the combined capacity request.
45. The base station according to claim 44, wherein the capacity reserving means is
arranged to reserve an individual amount of capacity for each subscriber stations, said
transmitting means informing the relay station of the individual amounts of capacity.
46. The base station according to any of claims 42 to 45, wherein in the event that
the combined capacity request does not include details of individual capacity requests,
the capacity reserving means is arranged to reserve an aggregate amount of capacity
for the subscriber stations, said transmitting means informing the relay station of the
aggregate amount of capacity.
47. A computer program which, when executed on a base station of a wireless
communication system, provides the base station according to any of claims 42 to 46.

A wireless communication method in which subscriber stations or mobile stations (MS)
communicate with a base station (BS), the base station being capable of performing
simultaneous communications with a number of connected subscriber stations by
allocating an available capacity among them. The subscriber stations are required to
issue capacity requests in order to obtain and/or maintain a connection with the base
station, and communications between the subscriber stations and the base station are
performed partly or wholly through at least one relay station (RS1#, RS2#). The
method involves, in the relay station, detecting capacity requests issued from a plurality
of the subscriber stations, using the detected requests to form at least one combined
capacity request, and transmitting the combined capacity request to the base station.
The base station responds to the combined capacity request by reserving capacity for
said plurality of subscriber stations, and the relay station or the base station allocates
the reserved capacity among the plurality of subscriber stations.