HK1161457A - Method and apparatus for increasing control channel capacity in geran - Google Patents

Description

Method and apparatus for increasing control channel capacity in GERAN

Technical Field

The present application relates to wireless communications.

Background

Various techniques have been developed to allow multiple users to reuse a single slot in a slotted wireless system, known as the multiuser reuse-one-slot (MUROS) technique or voice services over adaptive multiuser channels (VAMOS) over one slot. One such method includes using orthogonal sub-channels (OSCs). The OSC concept allows the radio network to multiplex two or more radio transmit/receive units and global system for mobile communications (GSM) channels that are allocated the same radio resources (i.e., time slots), and thus can significantly improve the capacity of multiple available Transceiver (TRX) hardware and possibly the capacity of spectrum resources. In addition, this feature may improve the offered voice capacity of full-rate and half-rate channels.

The method proposed by MUROS/VAMOS enables voice services carried on a traffic channel to be simultaneously provided to two or more users within one time slot through the same physical channel or time slot. One of the multiplexed users may be a legacy user according to the considered MUROS/VAMOS technique. Legacy users may be implemented with or without Single Antenna Interference Cancellation (SAIC) or Downlink Advanced Receiver Performance (DARP) support. It is therefore desirable to have a new type of MUROS/VAMOS device that relies on a DARP-like interference-type cancellation receiver. In addition, it would be desirable to have new MUROS/VAMOS devices that can support features such as additional training sequences.

In the GSM system, the cell configuration of signaling resources and other basic system access parameters is broadcast as part of a system information message on a broadcast control channel. The primary signaling channel used in GSM systems to support call set signaling is referred to as a stand-alone dedicated control channel (SDCCH). SDCCH is typically used for registration purposes and other services such as the transmission of Short Message Service (SMS) messages and the activation or interrogation of additional services (SS). The operator may allocate a number of SDCCH resources based on the available number of channels/time slots in the GSM cell, the expected number of calls, and the traffic channel assignment.

For example, in many common GSM deployments where a cell may be equipped with two or three Transceivers (TRXs), typically one slot on a certain TRX is allocated to support control channels, such as Synchronization Channels (SCH), Frequency Correction Channels (FCCH), Broadcast Control Channels (BCCH), Paging Channels (PCH), Access Grant Channels (AGCH) and Random Access Channels (RACH). Additional slots on that TRX in frames occurring over a multi-frame period are allocated to carry SDCCH for SSs for call setup, SMS, and/or available traffic resources on the remaining TRX. In particular, one such common configuration used by most operators is to assign a time slot to the SDCCH. It should be noted that the SDCCH resources are time multiplexed over one or more consecutive 51-multiframe periods, resulting in a configuration that includes 8 available SDCCH sub-channels on the same time slot.

Fig. 1 shows Time Division Multiple Access (TDMA) frame mapping for control channels. It is known to perform SDCCH sizing according to tight (close) capacity by using a distribution of expected call arrivals and distribution of occurrences or call durations.

Due to the advent of MUROS/VAMOS and the increase in voice capacity for the same number of traffic slots, the number of intended users simultaneously supported on these traffic slots has increased dramatically. However, a significant portion of calls supported in terms of traffic capacity will be blocked or suffer from an unacceptable amount of call setup delay. It is therefore desirable to be able to determine the capacity size and accompanying SDCCH resource allocation in the cell used for the call setup procedure.

Although much attention has been given to GSM design considerations of the MUROS/VAMOS concept when used on traffic channels carrying speech, the prior art does not describe or address the adverse effects of MUROS/VAMOS on the signaling channel and size it according to the availability and amount of allocated channel/slot resources to support all expected activities in the cell.

One possibility to increase the SDCCH signalling resource is to simply allocate more slots for the SDCCH. However, a negative impact of this approach is that slot resources providing increased control signaling for the traffic are lost. Therefore, new methods and procedures are sought to provide increased traffic capacity of GSM cells using the MUROS/VAMOS concept on control channels such as SDCCH, to minimize the number of simultaneously required time slot resources or the number of frames or channels in a multiframe, and to guarantee call setup or SMS transfer delay or SS access delay similar to prior art GSM systems and deployments.

Disclosure of Invention

A method and apparatus for increasing control channel capacity in a GSM system is disclosed. In a first approach, the MUROS/VAMOS concept can be applied to the time slots or bursts carrying SDCCH. The GSM network may send multiple WTRU bursts simultaneously in one slot using slots allocated to carry control signaling traffic, additional services, or SMS. In a second approach, the control signaling to support call setup for voice services can be switched to the MUROS/VAMOS capable traffic channel as soon as possible, instead of being controlled by SDCCH. In a third approach, the channel coding format of bursts transmitted and received on signaling bursts and/or allocated traffic or SDCCH time slots or resources may be modified to provide additional link robustness and to overcome the inherent loss in consideration of two simultaneous WTRUs on the time slots used for signaling. In a fourth method, the WTRU may inform the GSM network that the WTRU is MUROS/VAMOS capable.

Drawings

The invention will be understood in more detail from the following description, given by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagram of a TDMA frame map for a control channel;

figure 2 is a diagram of a method of applying the MUROS/VAMOS concept to a time slot or burst that may carry a SDCCH;

fig. 3 is a diagram of an example multi-frame structure;

fig. 4 is a flow chart of control signaling for call setup to support voice services; and

figure 5 is a functional block diagram of a WTRU and a Base Station (BS) configured to apply the MUROS/VAMOS concept to a slot or burst carrying a SDCCH.

Detailed Description

The term "wireless transmit/receive unit (WTRU)" as referred to below includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a Personal Digital Assistant (PDA), a computer, or any other type of user device that may operate in a wireless environment. The term "base station" as referred to below includes, but is not limited to, a node B, a site controller, an Access Point (AP), or any other type of interfacing device that may operate in a wireless environment. The embodiments described below, which are independent of the details of any implementation implementing MUROS/VAMOS technology, can be equally applied to all technical solutions to implement the MUROS/VAMOS concept in GSM systems. Also, when combining the MUROS/VAMOS concept to choose to pair different users in different time slots or bursts, the advent of more complex schemes such as Frequency Hopping (FH) or interference diversity may not change the MUROS/VAMOS operating concept.

In the Uplink (UL) direction, the subchannels may be separated by using non-correlated training sequences. The first subchannel may use an existing training sequence and the second subchannel may use a new training sequence, or vice versa. Alternatively, only new training sequences may be used on both subchannels. Using OSC may enhance voice capacity with negligible impact on the WTRU and the network. Notably, OSC can be applied to all Gaussian Minimum Shift Keying (GMSK) modulated traffic channels (e.g., for full rate traffic channels (TCH/F), half rate traffic channels (TCH/H), associated Slow Associated Control Channels (SACCH), and Fast Associated Control Channels (FACCH)).

The OSC increases voice capacity by allocating two or more circuit switched voice channels (i.e., two or more separate calls) to the same radio resource. By changing the signal modulation from GMSK to Quadrature Phase Shift Keying (QPSK), where one modulation symbol represents two bits, it is relatively easy to separate two users-one user on the X-axis and a second user on the Y-axis of the QPSK constellation. A single signal contains information for two different users, each of which is assigned its own subchannel. Multiple users may share a single resource or time slot using higher order modulation schemes.

In the Downlink (DL), OSC can be implemented in a Base Station (BS) by using a QPSK constellation, which can be a subset of an 8PSK constellation, e.g., for Enhanced General Packet Radio Service (EGPRS). The modulation bits are mapped to QPSK symbols ("two bits") such that the first sub-channel (OSC-0) is mapped to the Most Significant Bit (MSB) and the second sub-channel (OSC-1) is mapped to the Least Significant Bit (LSB). The two sub-channels may use separate encryption algorithms, such as A5/1, A5/2, or A5/3. Some options for symbol rotation may be considered and optimized by different criteria. For example, a symbol rotation of 3 π/8 may correspond to EGPRS, a symbol rotation of π/4 may correspond to π/4-QPSK, and a symbol rotation of π/2 may provide a subchannel to emulate GMSK. Alternatively, the QPSK signal constellation may be designed such that it resembles a conventional GMSK modulation symbol sequence on at least one subchannel.

QPSK is the choice for MUROS/VAMOS modulation format for several reasons. First, QPSK provides robust signal-to-noise ratio (SNR) versus Bit Error Rate (BER) performance. Second, QPSK can be implemented by having available 8-PSK-capable RF hardware. And third, QPSK burst format can be introduced for release 7EGPRS-2 of packet switched services.

An alternative method of implementing MUROS/VAMOS in the downlink includes multiplexing two or more WTRUs by transmitting two or more independent GMSK modulated bursts in one time slot. Interference cancellation techniques such as DARP phase i or phase ii may be required in the receiver since this approach results in increased levels of inter-symbol interference (ISI). Generally, during the OSC mode of operation, a Base Station (BS) applies DL and UL power control with a Dynamic Channel Allocation (DCA) scheme to keep the difference in received downlink and/or uplink signal levels of the co-allocated subchannels within a window of, for example, ± 10 dB. The target value may depend on the type of receiver being multiplexed and other criteria. In the uplink, each WTRU may use a normal GMSK transmitter with an appropriate training sequence. The BS may use an interference cancellation or joint detection type receiver, such as a space-time interference rejection combining (STIRC) receiver or a Successive Interference Cancellation (SIC) receiver, to receive the orthogonal subchannels used by the different WTRUs.

OSC can be used in the DL, UL or both in conjunction with frequency hopping or user diversity schemes. For example, the subchannels may be allocated to different user pairs (pairs of users) on a per frame basis, and the pairs on a per slot basis may be reproduced in a pattern over an extended period of time (e.g., several frame periods or block periods).

Statistical multiplexing may also be used to allow more than two WTRUs to transmit using two available subchannels. For example, four WTRUs may transmit and receive voice signals over a 6 frame period by using one of two subchannels in an allocated frame.

An extension of the baseline concept, known as the alpha-QPSK modulation scheme, has been introduced. The alpha-QPSK modulation scheme presents a simple approach to power control for the in-band and quadrature components of the QPSK symbol constellation. By using the alpha parameter, the relative power on the MUROS/VAMOS time slots allocated to the first pair of second sub-channels on the time slot can be adjusted to be within + -10-15 dB of each other. Using this approach, the absolute power allocated by the transmitter to the composite MUROS/VAMOS transmission may not require the exact 1/2 power for each user (equal to the relative power of subchannel 1/the power of subchannel 2 at 0 dB). Other more desirable power ratios may be achieved, for example, when one of the MUROS/VAMOS subchannels (users) is in better signal conditions than the other users, and a power ratio of-3 dB (or higher) may result in better performance for the worse MUROS/VAMOS user. Along with the absolute transmit power setting with the MUROS/VAMOS composite signal on the slot, the α -QPSK concept can generate a relative power control component for MUROS/VAMOS users.

Another possible extension of this baseline OSC concept proposes multiplexing more than simple fixed pairs of users into exactly the same allocated burst by extending the concept to statistical multiplexing of more than two users over a period of at least several frames in a GSM multiframe structure. At any given point in time (i.e., any "burst"), no more than two users may transmit using the two available subchannels of the OSC burst. However, when using Half Rate (HR) coding (any WTRU that needs to transmit/receive one of two frames), statistical multiplexing of more than two users may be achieved. For example, four users may transmit/receive their HR speech signals in any specified six frame periods, using one of the two available OSCs in each burst and by transmitting only in their allocated frame.

A further possible modification of the baseline OSC concept suggests that reuse of the GSM FH technique may result in interference averaging and Discontinuous Transmission (DTX) gains for both OSC and non-OSC users, which gains are spread relatively evenly among WTRUs in a cell. Similar to the first possible modification, no more than two users may transmit using the two available subchannels of the OSC burst in any given burst (i.e., timeslot). However, by allocating different frequency hop sequences/Mobile Allocation Index Offsets (MAIOs) to different WTRUs in a cell, a WTRU may be paired with another WTRU at the next occurrence of a burst. After a certain number of frames, the pattern may be repeated as a function of the FH list. Note that this can apply to both DL and UL directions.

With respect to the UL direction, MUROS/VAMOS concepts and/or extensions, including the frequency hopping concept for statistically multiplexed handsets, it is proposed to use ordinary GMSK transmissions with different training sequences on the same time slot to allow the BS to distinguish between the two transmissions. Unlike the OSC DL, which may use QPSK, each of two or more WTRUs may transmit a legacy GMSK modulation burst. It may be assumed that the BS uses the STIRC or SIC receiver to receive the orthogonal subchannels used by different WTRUs.

With respect to the second technical concept related to implementation of a release 6DARP type i receiver in a WTRU, MUROS/VAMOS proposes that voice services may be provided to two or more users simultaneously on the same physical channel or timeslot. One of these multiplexed users may be a legacy user. Legacy WTRUs may or may not implement SAIC or DARP support. Similarly, the new MUROS/VAMOS device may rely on a DARP-type interference cancellation receiver. Furthermore, the new MUROS/VAMOS device may be expected to support features such as extended training sequences.

Figure 2 is a diagram of a first method in which the MUROS/VAMOS concept can be applied to a slot or burst carrying a SDCCH. SDCCH time slots carrying signaling may use distinct and different burst coding and protocol formats compared to traffic time slots carrying voice. In particular, the GSM network may include a BS210, which BS210 may use allocated time slots to carry control signaling traffic, additional services, or SMS to send more than one user burst simultaneously, e.g., WTRU 1220 and WTRU 2230 in the time slot.

For example, using QPSK or derivative (derivative) modulation types, a first user's SDCCH may be carried on a first OSC in a designated slot to carry SDCCH 240, while a second user's SDCCH is carried on a second subchannel in that slot 250 using a different constellation point or supplemental subset mapping of the modulation symbol stream. The concept can be extended to other modulation schemes, such as 16QAM, etc., or independent sub-channels are created by sending GMSK modulated bursts to two users simultaneously. In addition or in conjunction, the independent OSCs created on this slot can also be distinguished by using, for example, different training sequences to assist the channel estimation process.

The method of creating and supporting these OSCs on some or all of the SDCCH specified slot resources in the DL and UL may be the same or may be UL or DL specific. For example, QPSK or its derivatives may be used to create OSC in DL, while corresponding UL transmissions by individual users use GMSK modulation bursts, and may be detected using techniques such as IRC on the network side.

Using this approach, the number of available SDCCH resources may be doubled by the availability of more than one OSC per SDCCH time slot. Thus, capacity is enlarged to match signaling traffic with added voice traffic.

In one embodiment, the GSM cell may allow MUROS/VAMOS operation of all SDCCH resources. In another embodiment, a GSM cell may allow MUROS/VAMOS operation at a certain selected SDCCH resource, but not all of them are necessary. It should be noted that SDCCH resources may correspond to certain events, time slots (or bursts) of a frequency channel, and/or combinations of multi-frame events, time slots, or bursts of a frequency channel.

Fig. 3 is a diagram of an example multi-frame structure 300. Referring to fig. 3, if slot 1310 and slot 2320 on the channel occurring in multiple frames recurring in a multi-frame structure are reserved for SDCCH 325, slot 1 may be allocated to carry SDCCH for two users using MUROS/VAMOS on the available sub-channels OSC-0330 or OSC-1340. However, time slot 2320 may be configured to use SDCCH (or a single user burst per time slot) in a typical GSM system. This approach may be advantageously used for link performance reasons or in the case when the MUROS/VAMOS technique may not fully support the occurrence of time slots of a legacy GSM WTRU (e.g., a conventional receiver without the interference cancellation capability of the receiver). It will be apparent to those skilled in the art that the above example can be extended to a different number of SDCCH time slots or a division of these time slots.

In another embodiment, the GSM cell may allow MUROS/VAMOS operation for some or all SDCCH resources, but restrict certain WTRUs from using a particular OSC. The SDCCH resource may be a channel, a time slot, a burst, or a multi-frame event of these resources. This approach may be advantageously used in cases where the link characteristics of legacy devices rely on their ability to decode legacy burst formats (e.g., symbol rotation functions, or training sequences used on bursts carrying SDCCH information).

The GSM access network and/or WTRU may perform a procedure by which the configuration and access parameters of the SDCCH resources and the likelihood that each SDCCH time slot supports more than one burst may be made known by signaling or by application of rule settings known by the transmitter and receiver.

In one embodiment, the allocation and/or presence of SDCCH resources and the availability of MUROS/VAMOS OSCs on some or all of these SDCCH resources may be conveyed by an extension of the system information on the BCCH.

In another embodiment, the allocation, availability and/or presence of SDCCH resources and the availability of MUROS/VAMOS OSCs may be performed by immediate dispatch messages.

For example, the GSM access network may signal burst formats, and/or allowed (or used) training sequences or training sequence codes, applicable or to be allocated, for the reserved SDCCH resources in the cell, such as the MUROS/VAMOS OSC of time slots, channel numbers, frame occurrences, and/or the above, or an equivalent thereof. The WTRU may perform a procedure by which access to the DL and/or UL SDCCH may be configured as a function of the received configuration information from the access network.

In a second approach, control signaling to support call setup for voice services can be switched as early as possible to MUROS/VAMOS capable traffic channel or timeslot resources, rather than being controlled by SDCCH. One advantage of this approach is that the total number of signalling exchanges on the SDCCH for execution may be severely reduced. Thus, SDCCH may be released earlier than typical techniques. Thus, by reducing the number of message exchanges that occur on the actual SDCCH specified resource and moving all or a portion thereof to the traffic resource, the capacity problem on the SDCCH can be mitigated.

Fig. 4 is a flow chart of control signaling for call setup supporting voice services. In one embodiment, upon receiving the channel request message 410 from the WTRU 420, the BS 430 in the GSM network may assign a MUROS/VAMOS OSC using a time slot belonging to a traffic resource in the cell. The BS 430 may send a response to the WTRU 420 using an instant assignment message 450 on the timeslot. The traffic resource may be unallocated (and thus currently unused) or the traffic slot may be used by another voice user.

Extending this example, the GSM network may indicate to the WTRU that the channel type used for the allocated traffic resource is a control type when using the instant assignment message. After performing the initial signaling, the network may then change the channel mode from control type or signaling to traffic type or voice at some point in time by sending a channel mode modification message. Note that the WTRU may remain on the same resource, but may first use the resource as a signaling channel and then switch to use the resource as a traffic channel at a later point in time. By advantageously using MUROS/VAMOS capabilities implemented in the WTRU and the network, signaling traffic for call setup purposes may be carried on the traffic resource, even where another call for another user may be simultaneously supported.

It will be apparent to those skilled in the art that the above procedure can be modified to perform the conversion from a dedicated separate signalling resource, such as SDCCH, to a traffic slot at some later point in time during the call set-up phase.

For example, the GSM access network may signal burst formats, and/or allowed training sequences or training sequence codes for traffic slots, such as time slots, channel numbers, FH parameters, frame occurrences, and/or MUROS/VAMOS OSC or equivalents, that are applicable or to be allocated. The WTRU may perform a procedure by which access to DL and/or UL traffic resources is configured as a function of the received configuration information from the access network.

In a third approach, the channel code format of the signaling burst and/or the bursts or resources transmitted and received on the assigned traffic or SDCCH time slots may be modified to provide additional link robustness and overcome the inherent (inrinsic) 3dB link loss while allowing two simultaneous users on the time slots used for signaling.

In one embodiment, when signaling is switched and carried early on the MUROS/VAMOS traffic resources, the channel coding of the signaling bursts may be increased to provide a bias in channel decoding performance and overcome the inherent link loss when using the MUROS/VAMOS resources.

In another embodiment, more robust channel coding on a signaling burst may be achieved by repetition of all or a selected subset of the coded bits during the burst mapping procedure. Alternatively, more robust coding of the signaling burst may be performed by repetition of the signaling block (typically 4 bursts) or by reducing the signaling coding rate (the ratio of information bits over channel coding bits) when compared to the coding rate used for signaling bursts in a typical GSM system.

In another embodiment, signaling bursts or blocks may be transmitted on MUROS/VAMOS capable traffic slots by allowing reception and/or transmission in only a selected subset of frames in a multi-frame structure. For example, by specifying that signaling bursts are sent only in idle frames of other users, the number of available channel bits may be increased or a lower order modulation type may be used, both of which increase decoding performance for the bursts.

The use and applicability of a more robust coding mechanism applied to signaling bursts or blocks may be configured by the GSM network by, for example, using signaling messages on a broadcast channel or by instant assignment messages, etc.

To properly power the above techniques, the network WTRU may be informed (by the WTRU) that it is MUROS/VAMOS capable. For example, when the WTRU sends a channel request message to the network, the WTRU may inform the network that the WTRU is MUROS/VAMOS capable by sending the MUROS/VAMOS capability of the WTRU as part of or included in the RACH.

Fig. 5 is a functional block diagram of a WTRU500 and a BS 550 configured in accordance with the above-described method. The WTRU500 includes a processor 501 in communication with a receiver 502, a transmitter 503, and an antenna 504. The processor 501 may be configured to apply the MUROS/VAMOS concept on a control channel such as SDCCH as described above. The BS 550 includes a processor 551, a transmitter 553, an antenna 554, and a channel allocator 555 in communication with a receiver 552. The channel allocator 555 may be part of the processor 551 or may be a separate unit in communication with the processor 551. Channel allocator 555 may be configured to apply the MUROS/VAMOS concept on a control channel, such as a SDCCH as described above. The WTRU500 may include additional transmitters and receivers (not shown) in communication with the processor 501 and the antenna 504, as well as other components described above, for multi-mode operation. The WTRU500 may include additional operational components (not shown) such as a display, keypad, microphone, speaker, or other components.

Examples

1. A method for increasing control system capacity in a GSM network using multi-user reuse of one time slot (MUROS), the method comprising:

bursts are transmitted simultaneously to more than one wireless transmit/receive unit (WTRU) in a time slot allocated to carry control signaling traffic, additional services, or Short Message Service (SMS).

2. The method of embodiment 1 wherein the time slots are designated to carry a stand-alone dedicated control channel (SDCCH).

3. The method as in any one of embodiments 1-2, further comprising:

modulating a first WTRU SDCCH on a first sub-channel in the time slot; and

a second WTRU SDCCH is modulated on a second sub-channel in the time slot using a constellation point or supplemental subset mapping of the modulated SDCCH.

4. The method of embodiment 3 wherein the first subchannel and the second subchannel are created by simultaneously sending GMSK modulated bursts to the first WTRU and the second WTRU.

5. The method as in any one of embodiments 3-4 wherein subchannels created in a time-slot are distinguished by using different training sequences.

6. A method as in any of embodiments 1-5 wherein the creation and support of sub-channels on SDCCH designated slot resources in the downlink is the same as the creation and support of sub-channels on SDCCH designated slot resources in the uplink.

7. A method as in any of embodiments 1-6 wherein the creation and support of sub-channels on SDCCH designated slot resources in the downlink is different from the creation and support of sub-channels on SDCCH designated slot resources in the uplink.

8. The method as in any one of embodiments 6-7 wherein QPSK modulation is used for the created sub-channels in the downlink.

9. The method as in any one of embodiments 6-8 wherein the GMSK modulated bursts are on a created subchannel in the uplink.

10. The method as in any of embodiments 1-9 wherein MUROS operation is used on all SDCCH resources.

11. The method as in any of embodiments 1-9 wherein MUROS is used on selected SDCCH resources.

12. The method as in any one of embodiments 1-11 wherein the SDCCH resource corresponds to certain occurrences of frequency channels, time slots, and/or combinations of multi-frame occurrences of these.

13. The method as in any one of embodiments 1-12, further comprising:

configuring a first slot to carry SDCCH for two WTRUs using MUROS on a first available subchannel or a second available subchannel; and

the second slot is configured to use the SDCCH for one WTRU.

14. The method as in any of embodiments 1-13 wherein MUROS operation is used on selected SDCCH resources but the WTRU is restricted to use a particular subchannel.

15. The method as in any one of embodiments 1-14, further comprising:

system information is transmitted between the network and the WTRU on the BCCH, wherein the system information includes the allocation and/or presence of SDCCH resources and the availability of MUROS subchannels.

16. The method as in any one of embodiments 1-15, further comprising:

transmitting an instant assignment message between the network and the WTRU, wherein the system information includes an allocation and/or presence of SDCCH resources and an availability of MUROS subchannels.

17. A method for increasing control system capacity in a GMS network using multi-user reuse of a time slot (MUROS), the method comprising:

upon receiving a "channel request" message from a wireless transmit/receive unit (WTRU), the GSM network assigns MUROS subchannels using an "immediate assignment" message on time slots belonging to traffic resources in a cell.

18. The method of embodiment 17, wherein the traffic resource is unallocated.

19. The method as in any one of embodiments 17-18 wherein traffic slots are used by more than one WTRU.

20. The method as in any one of embodiments 17-19, further comprising:

the GSM network indicates to the WTRU that the channel type for the assigned traffic resource is "control type".

21. The method as in any one of embodiments 17-20, further comprising:

the GSM network sends a "channel mode modification" message to the WTRU to change the channel mode from a "control type or signaling" mode to a "traffic type or voice" mode.

22. A method as in any of embodiments 17-21 wherein a WTRU is switched from a stand-alone dedicated control channel (SDCCH) to a traffic slot at a point in time during a call setup phase.

23. A method for increasing control system capacity in a GSM network using multi-user reuse of one time slot (MUROS), the method comprising:

channel coding of signaling bursts is performed on assigned traffic or stand-alone dedicated control channel (SDCCH) time slots to provide additional link robustness and to overcome the inherent loss of 3dB while allowing two wireless transmit/receive units (WTRUs) on one time slot at the same time.

24. The method of embodiment 23 wherein when signaling is switched early and carried over MUROS traffic resources, the channel coding of the signaling burst is increased to provide an offset in channel decoding performance and overcome inherent losses when MUROS resources are used.

25. The method as in any one of embodiments 23-24 wherein channel coding of a signaling burst is accomplished by repetition of all or a selected subset of coded bits in a burst mapping procedure.

26. The method as in any one of embodiments 23-25 wherein channel coding of the signaling bursts is accomplished by repetition of signaling blocks.

27. The method of embodiment 26 wherein the signaling block comprises 4 bursts.

28. The method as in any one of embodiments 23-27 wherein channel coding of the signaling burst is accomplished by reducing a channel coding rate, which is a ratio of information bits to channel coded bits.

29. The method as in any one of embodiments 23-28, further comprising:

signaling bursts or blocks are transmitted over MUROS-capable traffic slots, over which time slot reception or transmission of signaling bursts is permitted only in selected subsets of frames in a multi-frame structure.

30. The method of embodiment 29 wherein a signaling burst is transmitted during one of the idle frames of the WTRU, thereby increasing the number of available channel bits.

31. The method as in any one of embodiments 23-30 wherein the coding scheme is applied to the signaling bursts by the GSM network using signaling messages or instant assignment messages.

32. The method as in embodiment 31 wherein the signaling message is sent on a broadcast channel.

33. The method as in any one of embodiments 23-32 further comprising the WTRU notifying the GSM network that the WTRU is MUROS capable.

34. The method of embodiment 33 wherein when the WTRU transmits a channel request message to the GSM network, the WTRU transmits its MUROS capability using a Random Access Channel (RACH).

35. A WTRU configured to perform the method of any one of embodiments 1-34.

36. A node B configured to perform the method of any of embodiments 1-34.

37. An apparatus configured to perform the method of any of embodiments 1-34.

38. A wireless communication system configured to perform the method of any of embodiments 1-34.

39. A method for controlling channel operation, the method comprising:

generating a multiframe including at least one control frame, the at least one control frame including a timeslot including a first Orthogonal Subchannel (OSC) and a second OSC;

the SDCCH is allocated to carry a control signaling service; and

transmitting the multiframe.

40. The method of embodiment 39, wherein the at least one control frame is designated to carry a stand-alone dedicated control channel (SDCCH).

41. The method of embodiment 40, further comprising:

modulating a first wireless transmit/receive unit (WTRU), SDCCH, on a first OSC in the time slot; and

modulating a second WTRU SDCCH on a second OSC in the time slot using a different constellation point or supplemental subset mapping than the constellation point or supplemental subset mapping for the first OSC.

42. The method of embodiment 41 wherein the first and second OSCs created in the timeslot are distinguished by using different training sequences.

43. The method as in any one of embodiments 40-42 wherein the OSC on the SDCCH specified slot resource in the downlink is the same as the OSC on the SDCCH specified slot resource in the uplink.

44. A method as in any of embodiments 40-42 wherein the OSC on a SDCCH designated slot in the downlink is different from the OSC on a SDCCH designated slot in the uplink.

45. The method as in any one of embodiments 40-44, further comprising:

configuring a first timeslot to carry SDCCH for two wireless transmit/receive units (WTRUs) using a first OSC and a second OSC; and

the second slot is configured to carry the SDCCH for one WTRU.

46. The method as in any one of embodiments 40-45, further comprising:

system information is transmitted to a wireless transmit/receive unit (WTRU) on a Broadcast Control Channel (BCCH), where the system information includes the allocation or presence of SDCCH resources and the availability of OSCs.

47. The method as in any one of embodiments 40-46, further comprising:

an instant assignment message is transmitted to a wireless transmit/receive unit (WTRU), the instant assignment message containing system information and including an allocation or presence of SDCCH resources and availability of OSCs.

48. A method for increasing control system capacity in a GSM network using multi-user reuse of one time slot (MUROS/VAMOS), the method comprising:

receiving a request message from a wireless transmit/receive unit (WTRU); and

the orthogonal sub-channel (OSC) is assigned using the response message.

49. The method of embodiment 48, further comprising:

the response message is transmitted on a time slot belonging to the traffic resource.

50. The method as in embodiment 49 wherein the traffic resource is an unallocated traffic resource.

51. The method of embodiment 49 or 50 wherein traffic slots are used by more than one WTRU.

52. A wireless transmit/receive unit (WTRU), comprising:

a receiver configured to receive a multiframe comprising at least one control frame, the at least one control frame comprising a timeslot including a first orthogonal sub-channel (OSC) and a second OSC; and

a processor configured to decode one of the first OSC or the second OSC and recover the control frame.

53. The WTRU of embodiment 52 wherein the receiver is configured to receive at least one control frame designated to carry a stand-alone dedicated control channel (SDCCH).

54. The WTRU of embodiment 52 or 53 wherein the receiver is configured to receive system information on a Broadcast Control Channel (BCCH), the system information including an allocation or presence of SDCCH resources and availability of OSCs.

55. A WTRU as in any of embodiments 52-54 wherein the receiver is configured to receive an instant assignment message containing system information and including an allocation or presence of SDCCH resources and availability of OSCs.

56. A Base Station (BS), the BS comprising:

a channel allocator configured to:

generating a multiframe comprising at least one control frame, said at least one control frame comprising time slots,

the timeslot includes a first orthogonal sub-channel (OSC) and a second OSC, an

The SDCCH is allocated to carry a control signaling service; and

a transmitter configured to transmit the multiframe.

57. The BS of embodiment 56, wherein the channel allocator is configured to generate a multiframe comprising at least one control frame designated to carry a stand-alone occupancy control channel (SDCCH).

58. The BS of embodiment 56 or 57, further comprising:

a processor configured to:

modulating a first wireless transmit/receive unit (WTRU), SDCCH, on a first OSC in the time slot; and

a second WTRU SDCCH is modulated on a second OSC in the time slot using a different constellation point or supplemental subset mapping than the constellation point or supplemental subset mapping used for the first OSC.

59. The BS of embodiment 58 wherein the processor is configured to modulate the first OSC and the second OSC in the timeslot using different training sequences.

60. The BS as in any one of embodiments 56-59 wherein the channel allocator is configured to configure a first slot to carry SDCCH for two wireless transmit/receive units (WTRUs) using the first and second OSCs and a second slot to carry SDCCH for one WTRU.

61. The BS as in any one of embodiments 56-60 wherein the transmitter is configured to transmit system information to a wireless transmit/receive unit (WTRU) on a Broadcast Control Channel (BCCH), wherein the system information comprises an allocation or presence of SDCCH resources and availability of OSCs.

62. The BS as in any one of embodiments 56-61 wherein the transmitter is configured to transmit an instant assignment message to a wireless transmit/receive unit (WTRU), the instant assignment message containing system information and including an allocation or presence of SDCCH resources and availability of OSCs.

Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of the computer readable storage medium include Read Only Memory (ROM), Random Access Memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and Digital Versatile Disks (DVDs).

Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of Integrated Circuit (IC), and/or a state machine.

A processor in association with software may be used to implement a wireless frequency transceiver on a Wireless Transmit Receive Unit (WTRU), User Equipment (UE), terminal, base station, Radio Network Controller (RNC), or any host computer. The WTRU may be used in conjunction with a module that is implemented in hardware or software, such as a camera, a video camera module, a videophone, a loudspeaker, a vibrating device, a speaker, a microphone, a television transceiver, a hands-free headset, a keyboard, a bluetooth module, a Frequency Modulated (FM) radio unit, a Liquid Crystal Display (LCD) display unit, an Organic Light Emitting Diode (OLED) display unit, a digital music player, a media player, a video game playback module, a web browser, and/or any Wireless Local Area Network (WLAN) or Ultra Wideband (UWB) module.

Claims (20)

1. A method for controlling channel operation, the method comprising:

generating a multi-frame comprising at least one control frame, wherein the at least one control frame is designated to carry a stand-alone dedicated control channel (SDCCH), and the at least one control frame comprises a slot having a first orthogonal sub-channel (OSC) and a second OSC;

the SDCCH is allocated to carry a control signaling service; and

transmitting the multiframe.

2. The method of claim 1, further comprising:

modulating a first wireless transmit/receive unit (WTRU), SDCCH, on a first OSC in the time slot; and

modulating a second WTRU SDCCH on a second OSC in the time slot using a different constellation point or supplemental subset mapping of the modulated SDCCH than the constellation point or supplemental subset mapping for the first OSC.

3. The method of claim 2, wherein a first OSC and a second OSC in the timeslot are distinguished by using different training sequences.

4. The method according to claim 1, wherein the OSC on a SDCCH specified time slot in the downlink is the same as the OSC on a SDCCH specified time slot in the uplink.

5. The method according to claim 1, wherein the OSC on a SDCCH specified time slot in the downlink is different from the OSC on a SDCCH specified time slot in the uplink.

6. The method of claim 1, further comprising:

configuring a first timeslot to carry SDCCH for two wireless transmit/receive units (WTRUs) using the first and second OSCs; and

the second slot is configured to carry the SDCCH for one WTRU.

7. The method of claim 1, further comprising:

system information is transmitted to a wireless transmit/receive unit (WTRU) on a Broadcast Control Channel (BCCH), where the system information includes the allocation or presence of SDCCH resources and the availability of OSCs.

8. The method of claim 1, further comprising:

an instant assignment message is transmitted to a wireless transmit/receive unit (WTRU), the instant assignment message containing system information and including an allocation or presence of SDCCH resources and availability of OSCs.

9. A method for increasing control system capacity in a GSM network using multi-user reuse of one time slot (MUROS/VAMOS), the method comprising:

receiving a request message from a wireless transmit/receive unit (WTRU); and

the orthogonal sub-channel (OSC) is assigned using a response message on a slot belonging to a traffic resource.

10. The method of claim 9, wherein the traffic resource is an unallocated traffic resource.

11. The method of claim 9 wherein the time slot is used by more than one WTRU.

12. A wireless transmit/receive unit (WTRU), comprising:

a receiver configured to receive a multi-frame comprising at least one control frame, wherein the at least one control frame is designated to carry a stand-alone dedicated control channel (SDCCH) and the at least one control frame comprises a slot having a first orthogonal sub-channel (OSC) and a second OSC; and

a processor configured to decode one of the first OSC or the second OSC and recover the control frame.

13. The WTRU of claim 12 wherein the receiver is configured to receive system information on a Broadcast Control Channel (BCCH), the system information including an allocation or presence of SDCCH resources and availability of OSCs.

14. The WTRU of claim 12 wherein the receiver is configured to receive an instant assignment message containing system information and including an allocation or presence of SDCCH resources and availability of OSCs.

15. A Base Station (BS), the BS comprising:

a channel allocator configured to:

generating a multiframe comprising at least one control frame, wherein the at least one control frame is designated to carry a stand-alone dedicated control channel (SDCCH), and the at least one control frame comprises a timeslot having a first orthogonal sub-channel (OSC) and a second OSC, and

the SDCCH is allocated to carry a control signaling service; and

a transmitter configured to transmit the multiframe.

16. The BS of claim 15, further comprising:

a processor configured to:

modulating a first wireless transmit/receive unit (WTRU), SDCCH, on a first OSC in the time slot; and

modulating a second WTRU SDCCH on a second OSC in the time slot using a different constellation point or supplemental subset mapping than the constellation point or supplemental subset mapping used for the first OSC.

17. The BS of claim 16 wherein the processor is configured to modulate the first and second OSCs in the timeslot using different training sequences.

18. The BS of claim 15 wherein the channel allocator is configured to configure a first timeslot to carry SDCCHs for two wireless transmit/receive units (WTRUs) using the first and second OSCs and a second timeslot to carry SDCCH for one WTRU.

19. The BS of claim 15, wherein the transmitter is configured to transmit system information to a wireless transmit/receive unit (WTRU) on a Broadcast Control Channel (BCCH), wherein the system information includes an allocation or presence of SDCCH resources and availability of OSCs.

20. The BS of claim 15 wherein the transmitter is configured to transmit an instant assignment message to a wireless transmit/receive unit (WTRU), the instant assignment message containing system information and including an allocation or presence of SDCCH resources and availability of OSCs.