HK1176790A - A method for utilizing channel assignment information implemented by wtru and wtru - Google Patents

Abstract

The present invention provides a method for utilizing channel assignment information for an uplink channel or a downlink channel implemented by a wireless transmit/receive unit (WTRU) and a wireless transmit/receive unit (WTRU), the method comprising: receiving information via a downlink control channel; determining whether the information is intended for the WTRU; and utilizing the information on a condition that the information is intended for the WTRU. The WTRU comprising: means for receiving information via a downlink control channel; means for determining whether the information is intended for the WTRU; and means for utilizing the information on a condition that the information is intended for the WTRU.

Description

Method implemented by WTRU for using channel allocation information and WTRU

The present application is a divisional application of the present invention patent application entitled "method and system for providing channel assignment information for supporting uplink and downlink channels" filed on 18/11/2004 with application number 200480028878.0.

Technical Field

The present invention relates to wireless communication systems, and more particularly, to methods and systems for providing channel allocation information to support uplink and downlink transmissions.

Background

High Speed Downlink Packet Access (HSDPA) has been developed to increase Downlink (DL) efficiency and overall throughput in wideband code division multiple access (W-CDMA) systems released at the 5 th time (R5) of the Universal Mobile Telecommunications System (UMTS). A key advantage of HSDPA over UMTS R99/R4 is fast and dynamic link adaptation in DL and fast layer l hybrid automatic repeat request (H-ARQ). The adaptation of the fast link is achieved by fast scheduling of DL transmissions in the base station and coupling with the fast layer 1 DL signaling channel. The signaling channel, high speed shared control channel (HS-SCCH), conveys radio resource configuration information to a plurality of wireless transmit/receive units (WTRUs).

In Frequency Division Duplex (FDD), the HS-SCCH is sent with a channelization code (code) with Spreading Factor (SF) =128 during a three (3) slot Transmission Time Interval (TTI). The HS-SCCH indicates that data is to be transmitted to the WTRU on a high speed downlink shared channel (HS-DSCH) after a specific time offset. The HS-SCCH carries the following information: 1) channelization-code-set information (7 bits); 2) modulation scheme information (1 bit); 3) transport-block size information (6 bits); 4) H-ARQ process information (3 bits); 5) redundancy and constellation (constellation) version (3 bits); 6) new data pointer (1 bit); 7) WTRU identity (16 bits).

The HS-SCCH is sent (2 ms TTI) over three (3) slots, but consists of two (2) fields. Domain 1 (first time slot) contains channelization code mapping and modulation format information; and field 2 (second and third slots) contains the transport block size, H-ARQ information, redundancy version, and a new data pointer along with a specific WTRU Cyclic Redundancy Check (CRC).

Optionally, Enhanced Uplink (EU) increases Uplink (UL) efficiency and throughput. H-ARQ and node B scheduling are part of the EU. Similar to HSDPA, the new shared DL control channel for EU operation provides fast and dynamic adaptation of UL radio resources for UL transmissions. The shared DL control channel for EU needs to guarantee low-configuration potential for UL transmission and efficient radio resource management. Hereinafter, for the purpose of EU, the shared DL control channel is simply referred to as UL resource allocation channel.

To perform EU and HSDPA, another UL resource allocation channel for EU can be introduced on the existing HS-SCCH of HSDPA. Therefore, it is possible to introduce a scattered (separate) set of Spreading Factor (SF) =128DL channels like UL resource allocation channel. With this approach, the WTRU would need to monitor one or more UL resource allocation channels in addition to the HS-SCCH for HSDPA operation. While this approach is conceptually simple, there are a number of disadvantages in this scheme, such as WTRU complexity, WTRU battery efficiency, and DL spreading code usage.

Therefore, in order to support both EU and HSDPA operations, an efficient EU channel allocation scheme is necessary.

Disclosure of Invention

The present invention provides a method implemented by a wireless transmit/receive unit (WTRU) for using channel allocation information for an uplink channel or a downlink channel, the method comprising: receiving information via a downlink control channel; determining whether the information is for use as the WTRU; and using the information on a condition that the information is for use as the WTRU.

The present invention also provides a wireless transmit/receive unit (WTRU) comprising: means for receiving information via a downlink control channel; means for determining whether the information is for use as the WTRU; and means for using the information on a condition that the information is for use as the WTRU.

In one embodiment, the present invention is a method and wireless communication system for providing channel allocation information to support an UL channel and a DL channel. The system includes at least one node-B and at least one WTRU. The WTRU communicates with the node B via a shared control channel, an UL channel, and a DL channel. The WTRU receives a message from the node-B via a shared control channel. The message includes an indication of whether the message is used as an allocation of radio resources for an UL channel or a DL channel. The WTRU determines whether the message is intended for the WTRU and if so, whether the message is intended for allocation of radio resources for either the UL channel or the DL channel. Whether the message is used to allocate radio resources for the UL channel or the DL channel the WTRU takes appropriate action.

In another embodiment, the present invention is a method and slotted wireless communication system. The system includes at least one node-B, a Radio Network Controller (RNC) controlling the node-B, and at least one WTRU communicating with the node-B via a common control channel, UL channel, and DL channel. The RNC sends a message to the WTRU to indicate which slot TTIs support UL channel transmission and which slot TTIs support DL channel transmission.

Drawings

A more detailed understanding of the present invention can be obtained from the following preferred examples, which are given by way of illustration and are to be understood in conjunction with the accompanying drawings, in which:

figure l is a block diagram of a wireless communication system operating in accordance with the present invention;

fig. 2 is a look-up table for channelization code set mapping in HSDPA for use with the system of fig. 1; and

fig. 3 is a process flow diagram including method steps for performing uplink channel assignment signaling in accordance with the present invention.

Detailed Description

The present invention will be described with reference to the drawing figures wherein like numerals represent like elements throughout.

Hereinafter, the dedicated term "WTRU" includes, but is not limited to, a user equipment, a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, the terminology "node B" includes but is not limited to a base station, a location controller, an access point, or any other type of interfacing device in a wireless environment.

The present invention is applicable to any type of wireless communication system, such as UMTS Time Division Duplex (TDD) and FDD, Time Division Synchronous Code Division Multiple Access (TDSCDMA), code division multiple access 2000 (CDMA 2000), and CDMA in general, or any other type of wireless communication system.

The features of the present invention may be incorporated as part of an Integrated Circuit (IC) or be configured in a circuit comprising a multitude of interconnecting components.

The present invention will be described with reference to HSDPA and EU, and the terms HSDPA and EU are used interchangeably with DL and UL, respectively, it being understood that references to HSDPA and EU are only for purposes of describing preferred embodiments of the present invention, and the teachings of the present invention are applicable to any system utilizing a common control channel to convey channel allocation information for both UL and DL transmissions.

Fig. 1 is a block diagram of a system 100 for supporting UL and DL operations in accordance with the present invention. The system 100 includes an RNC 102, a node B104, and a WTRU 106. The node-bs 104 are controlled by the RNC 102 and dynamically allocate radio resources from the WTRUs 106 and UL and DL transmissions to the WTRUs 106. Three channels are established between the node-B104 and the WTRU 106. The channels are DL channel 108, UL channel 110, and common control channel 112. The common control channel 112 is used for transmission of channel allocation information for UL and DL transmissions.

The node B104 is configured to support HSDPA and EU operation. Thus, each node-B104 dynamically allocates radio resources for DL and UL transmissions to and from the WTRU 106 over the HS-DSCH and EU channels, respectively. Radio resource allocation information for the HS-DSCH and EU is transmitted through a common control channel 112.

According to the present invention, the common control channel 112 is a transmission of radio resource allocation information for UL and DL transmissions, and provides a specific indication to distinguish whether the radio resource allocation is for UL or DL transmissions. Thus, the common control channel 112 occupies a shared DL radio resource space, defined by a set of channelization codes (channelization codes) of SF =128, and is used for both DL and UL transmissions, and the WTRU 106 is configured to identify whether a particular transmission is used as a radio resource for allocating either DL or UL transmissions.

According to a first embodiment of the present invention, the indication that a specific radio resource is allocated for UL transmission is provided by means of one or more combinations of combinations not possible in the current channelization code set mapping of HSDPA. Fig. 2 is a look-up table for channelization code set mapping currently used in HSDPA. The HS-SCCH uses seven (7) bits to inform the WTRU 106 which SF =16 channelization codes are used for the corresponding HS-DSCH. Out of the 128 possible combinations, eight (8) combinations are currently not used for HSDPA (see "redundant area" labeled in fig. 2). One or more of the eight (8) unused combinations are for allocating radio resources or indicating demodulation transmission for UL transmission, not DL transmission. Thus, if the WTRU 106 determines that the set of channelization codes corresponds to one of the combinations of fig. 2 that are not possible, the WTRU 106 identifies that the transmission is an allocation for radio resources for UL transmissions instead of DL transmissions or identifies that the codes corresponding to the set of channelization codes are allocated for UL transmissions.

According to a second embodiment of the invention, the indication that a specific radio resource is allocated for UL transmission is provided by means of a WTRU-specific CRC. In the current HSDPA specification, the WTRU-specific CRC is included in the HS-SCCH domain 2. A 16-bit CRC is calculated from the transmitted information and the calculated CRC is masked with a unique 16-bit WTRU Identity (ID), and the masked CRC is transmitted to the WTRU 106 as a WTRU-specific CRC.

In accordance with a second embodiment of the present invention, the WTRU-specific CRC is modified in a unique and deterministic manner to indicate that the demodulated transmission is for UL transmissions and not DL transmissions. For example, the WTRU-specific CRC for HSDPA is calculated to be reversed for EU before channel coding is performed. The WTRU 106 performs two (2) different comparisons in performing the CRC of the received transmission, preferably simultaneously. The WTRU 106 identifies the transmission as being used as HSDPA if the WTRU 106 succeeds in decoding the received transmission with the WTRU-specific CRC and the WTRU 106 identifies the transmission as being used as EU if the WTRU 106 succeeds in decoding the received transmission with the reverse WTRU-specific CRC.

According to a third embodiment of the invention, the indication that a specific radio resource is allocated for the EU is provided by means of a WTRU-specific masking sequence. In the current HSDPA specification, the 40-bit sequence of field i is masked by a 40-bit WTRU-specific intermediate code sequence generated by a 16-bit WTRU ID.

According to a third embodiment, the WTRU-specific masking in domain i is modified in a unique and deterministic manner to indicate that the transmission is to be used as EU instead of HSDPA. For example, the inverse 16-bit CRC generated in the second embodiment may be used to drive a 40-bit long masking sequence. The WTRU 106 may identify the transmission as being used as HSDPA if the WTRU 106 succeeds in decoding the received transmission with the WTRU-specific masking sequence, and the WTRU 106 may identify the transmission as being used as EU if the WTRU 106 succeeds in decoding the received transmission with the WTRU-specific masking sequence.

In this way, the WTRU 106 can distinguish whether EU or HSDPA channel allocations have been transmitted after having received the field/of HS-SCCH-only transmissions.

Alternatively, the WTRU IDs may be assigned by the network in such a way that a particular WTRU ID does not collide with another WTRU ID. For example, the reverse ID of a first WTRU of the EU may be used to indicate HSDPA service of a second WTRU. Therefore, synchronous detection of the occurrence of the UL resource allocation channel and the HS-SCCH is facilitated.

According to a fourth embodiment of the present invention, the indication that specific radio resources are allocated for the EU is provided by means of Radio Resource Control (RRC) context signaling. Preferably, the node B104 configures respective radio resources for transmission of the UL radio resource allocation and the DL radio resource allocation. Alternatively, the RNC 102 allocates respective radio resources for transmission of the UL radio resource allocation and the DL radio resource allocation by using the RRC signaling message.

For example, the RRC signaling message from the RNC 102 may inform the WTRU 106 in which TTI the HS-SCCH or UL resource allocation channel is expected. In the current R5HSDPA specification, fifteen (15) slots comprise one (1) frame and three (3) slots comprise one (1) TTL. The "even" TTIs may include, for example, slots 2, 4, 6, 8, 10, 12, and 14, and the "odd" TTIs may include, for example, slots 1, 3, 5, 7, 9, 11, 13, and 15.

According to the present invention, the RRC transmission indicates that the signal transmitted in the "even" TTI is for HS-SCCH and the transmission in the "odd" TTI is for the transmission of the UL resource allocation channel. By not allowing transmissions for the HS-SCCH to be transmitted in "odd" TTIs, backward compatibility of the R5WTRU may be guaranteed. The same set of SF =128 resources may be used for the HS-SCCH and UL resource allocation channels.

According to a fifth embodiment of the invention, the indication that specific radio resources are allocated for the EU is provided by means of layer l of the associated DL Dedicated Channel (DCH). One or more bits on the associated DL DCH indicate the UL resource allocation channel as imminent with respect to the HS-SCCH by means of a fixed and predetermined timing relationship.

Fig. 3 is a process flow diagram 200 including method steps for performing UL channel allocation signaling in accordance with the present invention. After the process 200 (step 202) begins, a message of radio resource allocation is transmitted from the node-B104 to the WTRU 106 via a common control channel. The WTRU 106 receives and demodulates the message using a predetermined code for each predetermined TTI (e.g., each 2 ms) (step 204). The WTRU 106 then determines whether the message is intended for the WTRU 106 (step 206). A WTRU-specific CRC may be used for this purpose. If the WTRU 106 determines that the message is for the WTRU 106, the WTRU 106 determines whether the message is for allocation of radio resources for performing DL transmission or UL transmission of any of the embodiments of the present invention described above (step 208). The WTRU 106 then takes appropriate action (step 210) to receive or transmit data packets via the DL or UL channel based on the determination of step 208. For example, the WTRU 106 may accurately identify when to initiate a data reception procedure via the DL channel 108 or when to initiate a data transmission procedure via the UL channel 110. Currently, HS-SCCH for HSDPA announces incoming packets for the WTRU with a fixed two (2) slot offset, whereas the invention enables the WTRU to be informed when the WTRU has an opportunity to transmit packets via the UL (i.e., four slots from now on).

While the invention has been shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as hereinbefore described.

Claims (20)

1. A method implemented by a wireless transmit/receive unit (WTRU) for using channel allocation information for an uplink channel or a downlink channel, the method comprising:

receiving information via a downlink control channel;

determining whether the information is for use as the WTRU; and

using the information on a condition that the information is for use as the WTRU.

2. The method of claim 1, wherein the information is channel allocation information.

3. The method of claim 1 wherein determining whether the information is used as a Cyclic Redundancy Check (CRC) masked by the WTRU based on WTRU identity.

4. The method of claim 3 wherein the WTRU identity masked CRC is derived from a sixteen bit CRC.

5. The method of claim 1, further comprising determining whether the information is used as the uplink channel or the downlink channel to allocate radio resources.

6. The method of claim 5, wherein the information indicates whether the information is used to allocate radio resources for the uplink channel or the downlink channel.

7. The method of claim 1, wherein using the information comprises transmitting on an uplink channel or a downlink channel.

8. The method of claim 1, wherein the uplink channel is a shared channel.

9. The method of claim 1, wherein the downlink channel is a shared channel.

10. The method of claim 1, wherein the downlink control channel is a shared channel.

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

means for receiving information via a downlink control channel;

means for determining whether the information is for use as the WTRU; and

means for using the information on a condition that the information is used as the WTRU.

12. The WTRU of claim 11 wherein the information is channel allocation information.

13. The WTRU of claim 11 wherein the means for determining whether the information is used as the WTRU masks a Cyclic Redundancy Check (CRC) based on a WTRU identity.

14. The WTRU of claim 13 wherein the WTRU identity masked CRC is derived from a sixteen bit CRC.

15. The WTRU as in claim 11 further comprising means for determining whether the information is used as the uplink channel or the downlink channel to allocate radio resources.

16. The WTRU of claim 15, wherein the information indicates whether the information is used to allocate radio resources for the uplink channel or the downlink channel.

17. The WTRU of claim 11 wherein the means for using the information comprises means for transmitting on an uplink channel or a downlink channel.

18. The WTRU of claim 11 wherein the uplink channel is a shared channel.

19. The WTRU of claim 11 wherein the downlink channel is a shared channel.

20. The WTRU of claim 11 wherein the downlink control channel is a shared channel.