HK1105065A - Wireless communication method and apparatus with reconfigurable architecture for supporting an enhanced uplink soft handover operation - Google Patents

Description

Wireless communication method and apparatus with optional re-architecture for supporting enhanced uplink soft handover operations

Technical Field

The present invention relates to wireless communication systems. More particularly, the present invention relates to a method and apparatus for supporting enhanced uplink soft handover (EU-SHO) operations with a re-configured Radio Network Controller (RNC) and a node-B.

Background

Methods for improving uplink coverage, throughput, and transmission delay are currently reviewed in the third generation partnership project (3GPP) in the release 6(R6) Universal Mobile Telecommunications System (UMTS) research project "frequency division duplex uplink enhanced" context.

To achieve these goals, it is widely anticipated that a node-B (base station) will assume responsibility for scheduling and allocating uplink resources (physical channels) to users. The principle is that the node-B can make more efficient decisions and manage uplink radio resources on a short-term basis than the rnc, even though the rnc retains coarse control. Similar approaches have been adopted in release 5(R5) High Speed Downlink Packet Access (HSDPA) in Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes of the universal mobile telecommunications system.

It is also contemplated that several independent uplinks are processed between a wireless transmit/receive unit (WTRU) and a universal terrestrial access network (UTRAN) within a shared time segment. One example is Medium Access Control (MAC) layer hybrid automatic repeat request (HARQ) or only medium access control layer automatic repeat request (ARQ) operation, where each transmission may require a different number of transmissions to be successfully received by the utran. To limit the impact on system architecture, it is expected that the protocol layers above the mac should not be affected by the introduction of enhanced uplink dedicated channel (EU-DCH). One requirement introduced by this is for the data in the queue to be passed to the Radio Link Control (RLC) protocol layer. Therefore, similar to hsdpa in the downlink, a utran reordering function is required to organize received data blocks according to queues generated by the wtru rlc entity.

Soft handover macro diversity operation requires centralized control of uplink transmissions in each cell in the active set. The active set may include a plurality of node bs. Retransmissions are generated until successful transmission is achieved by at least one node B. Successful transmission is not guaranteed by all node bs. Therefore, reordering successful transmissions may not be completed because a successful transmission completion group may not be available in any node B.

Disclosure of Invention

The present invention relates to a method and apparatus for supporting enhanced uplink soft handover (EU-soft handover) operations for a wireless transmit/receive unit (WTRU). The apparatus may be a multi-cell wireless communication system, a radio network controller, or an Integrated Circuit (IC) disposed in a radio network controller. A multi-cell wireless communication system includes at least two EU-soft handover node-Bs and a radio network controller. The RNC includes a first MAC entity that handles EU-DCH functionalities. When an eu-sho operation is not occurring in the wtru, the rnc is configured according to a first architecture; the rnc is configured according to a second architecture when the wtru is operating in eu-sho operation. According to a second architecture, a first mac entity of a rnc includes a first acknowledgement/negative acknowledgement (ACK/NACK) generator that generates a signal indicating whether an eu transmission generated from a wtru has been successfully received by the rnc, and a first uplink scheduler for scheduling the eu transmission for the wtru.

Each eu-sho node-B includes a second mac entity that handles eu-dch functionalities. The second mac entity includes a hybrid arq/arq which communicates with the rnc via a separate signaling channel.

When an eu-sho operation is not occurring in a wtru, a second mac entity in a node-B currently operating with the wtru may be configured to include a second ack/nack generator that sends a signal indicating whether an eu transmission generated from the wtru has been successfully received by the rnc, and a second ul scheduler for scheduling the eu transmission for the wtru. The first uplink scheduler may communicate with each eu-sho node-B via an eu frame protocol.

The second mac entity at the eu-sho node-B includes only h-arq/arq entities when the wtru is operating in soft handover.

Drawings

The invention will be understood in more detail from the following description of preferred embodiments and the accompanying drawings, in which:

FIG. 1 shows a first system configuration during normal operation (not in soft handover) in accordance with the present invention;

fig. 2 shows a second system configuration for a wtru operating in an eu-sho operation in accordance with the present invention;

fig. 3 is a process flow diagram including method steps implementing the system configuration of fig. 1 and 2.

Detailed Description

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

Hereinafter, the term "wtru" includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. The term "base station" as used hereinafter includes, but is not limited to, a node-B, site controller, access point or other type of interfacing device in a wireless environment.

As is commonly applied to the umts systems, CDMA2000 (code division multiple access 2000) and code division multiple access, the present invention may further be applied to time division duplex, frequency division duplex and time division synchronous code division multiple access (TD-SCDMA), although other wireless systems are also contemplated. For CDMA2000, the present invention can be implemented in EV-D0 (i.e., data only) and EV-DV (i.e., data and voice).

The features of the present invention may be incorporated into an integrated circuit or be configured in a circuit comprising a plurality of interconnected components.

In one embodiment, the present invention provides an enhanced uplink distributed universal terrestrial access network medium access control architecture scheme including a reordering function, an uplink scheduling function, an ack/nack generation function and a h-arq/arq entity. With the appropriate utran mac architecture, soft and hard handover will be efficiently supported, and mac data loss and rlc recovery will be reduced. The present invention addresses these needs by formulating preferred MAC architecture details.

Furthermore, the present invention proposes a scheme for allocating universal terrestrial access network medium access control architecture for enhanced uplink. The present invention also contemplates implementing a hybrid automatic repeat request/automatic repeat request entity at the node-B and implementing reordering functions within the rnc regardless of wtru operation scheme.

In addition, the present invention contemplates implementing uplink scheduling functions at the node-B and the rnc. However, for a wtru, only one uplink scheduling function is allocated to it at any time. Whether or not an uplink scheduling function is configured at the node-B or rnc depends on the wtru operating scheme (whether or not soft handover is possible).

It is important to note that the present invention is also intended to implement ack/nack generation functionality at the node B and the rnc. However, for the wtru, only one ack/nack generation function is allocated to it at any point in time. Whether ack/nack generation functionality is configured at the node B or rnc depends on the wtru operating scheme (whether soft handover is required).

During eu-sho operation, the higher layer maintains an active subset of eu cells for which eu-dch is maintained in a sho-sho macro-diversity state. The cells in the active subset are controlled by different eu-sho node-bs.

In accordance with the present invention, the architecture transition of the multi-cell wireless communication system between the first configuration and the second configuration is dependent upon whether an eu-sho operation has occurred.

Fig. 1 shows a first system configuration 100 of a wireless communication system including a rnc 105 and a node-B110 during normal operation (not in soft handover). The node bs may communicate with the wtru 115. The rnc 105 is configured to include a first mac entity 120. A first mac entity 120 in the rnc 105 handles eu dedicated channel functions and includes one or more re-ordering functional entities 125. Each re-ordering function entity 125 is in communication with higher protocol layers 130 within the rnc 105 and includes an associated data buffer (not shown). The node-B110 is configured to include a second mac entity 135 that handles eu-dch functionality, a hybrid automatic repeat request/automatic repeat request entity 140 having an ack/nack generator 145, and an uplink scheduler 150.

The h-arq/arq entity 140 is configured at the node-B110 to handle h-arq/arq functionality for a user. The re-ordering function 125 is configured to the rnc 105 to re-order currently received data blocks, i.e., Packet Data Units (PDUs), to support queued delivery to the upper protocol layers 130. A uplink scheduler 150 is configured at the node-B110 to schedule eu transmissions for the wtru 115. The ack/nack generator 145 is configured at the node-B110 to inform the wtru 115 of the success or failure of the uplink transmission. As shown in fig. 1, the ack/nack generator 145 is incorporated in the normal operating scenario into the hybrid automatic repeat request/automatic repeat request entity 140 of the node B110.

The re-ordering function 125 is not affected by intra-node-B eu service cell changes, i.e., hard handover. That is, the rnc's reordering buffers (not shown) do not need to be filled during eu service cell change in the node-B. Since the re-ordering buffer is not filled, there is no out-of-queue delivery to the RLC and no RLC recovery (WTRU side) is caused by an EU cell change in the node-B. The ack/nack and ul scheduling information is sent to the wtru 115 via fast layer one signaling. Therefore, the delay is very low.

Fig. 2 shows a second system configuration 200 for a wtru operating in an eu-sho operation according to the present invention. The transition from the first system configuration 100 to the second system configuration 200 occurs when the rnc 105 detects that the wtru 115 is transitioning from normal operation to eu-sho operation. The second system configuration 200 includes a radio network controller 205 and at least two (2) eu-sho node-bs 210(210a.. 210N) operating during eu-sho. The rnc 205 is configured to include a first mac entity 215 disposed at the rnc 205. The first mac entity 215 handles eu-dch functionalities and includes one or more re-ordering entities 220, an ack/nack generator 225 and an ul scheduler 230. Each re-ordering function entity 220 may communicate with higher protocol layers 235 within the rnc 205 and may include an associated data buffer (not shown). Each node-B210 is configured to include a second mac entity 240(240a.. 240N) and a h-arq/arq entity 245(245a.. 245N) for handling eu-dch functionality.

Each h-arq/arq entity 245 handles h-arq/arq functionality for a user. An uplink scheduler 230 in the mac entity 215 communicates with each of the node-bs 210 at the rnc 205 via eu frame protocols 250a.. 250N. The hybrid automatic repeat request/automatic repeat request entities 240a.. 240N communicate with the radio network controller 105 via signaling channels 255a.. 255N, respectively.

Still referring to fig. 2, during eu-sho operations, if a data block received at any eu-sho node-B210 is successfully decoded, i.e., the data block passes a Cyclic Redundancy Check (CRC), it is forwarded to the rnc 205 via eu frame protocols 255a.. 255N. Re-ordering function entity 220 at radio network controller 205 may perform re-ordering functions on correctly received data blocks to support in-queue delivery to higher protocol layers 235. The uplink scheduler 230 in the rnc 205 is responsible for scheduling eu transmissions to wtrus in cells controlled by different ones of the eu-sho node-B210. An ack/nack generator 225 in the rnc 205 may generate an ack transmission to the wtru when the rnc 205 receives at least one copy of a successfully decoded data block with a good crc check from the eu-sho node-B210. Otherwise, determining that the data block was not received correctly, the ack/nack generator 225 in the rnc 205 may then generate a negative transmission to the wtru.

Data blocks received from different ones of the eu-sho node-bs 210 may be combined and organized in queues for delivery to higher protocol layers 235. The re-ordering entity 220 disposed within the rnc 205 allows eu mac packet data units to be processed independently of the node-B that is provided to receive each packet data unit for successful reception and proper delivery to the higher protocol layers 235. Therefore, mac data and rlc recovery are reduced.

During eu-sho operations, ul transmissions scheduled by an eu-sho node-B210 may be received in resource and interference patterns by cells controlled by other eu-sho node-bs 210 using a ul scheduler 230 in the rnc 205.

Fig. 3 is a flow chart of a process 300 including method steps implementing the system configurations 100 and 200 shown in fig. 1 and 2, respectively. During normal operation, the rnc 105 continues to monitor for any indication that eu-sho operation is imminent (step 305). As shown in the system configuration 100 of fig. 1, during normal operation, i.e., before and after an eu-sho operation occurs, the current node-B110 of the wtru 115 is configured such that the current node-B110 includes an ack/nack generator 145 and an ul scheduler 150. If the rnc 105 detects that eu-sho operation is to begin in step 305, the mac entity 120 in the rnc 105 of fig. 1 is configured according to the mac entity 215 in the rnc 205 of fig. 2, whereby the mac entity 215 includes the ack/nack generator 225 and the uplink scheduler 230 (step 315). After the soft handover operation is completed, as determined in step 320, the ack/nack generator 225 and the uplink scheduler 230 in the mac entity 215 in the rnc 105 are disassembled (step 325), and the new node-B110 associated with the wtru 115 during the eu-sho operation is configured to include the ack/nack generator 145 and the uplink scheduler 150, as shown in fig. 1.

While the invention has been particularly 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 described above.

Claims (17)

1. A method for supporting enhanced uplink soft handover (EU-SHO) operations associated with a wtru and at least an EU-SHO node-B in communication with a Radio Network Controller (RNC) in a multi-cell wireless communication system, the radio network controller including a first Medium Access Control (MAC) entity that handles enhanced uplink dedicated channel (EU-DCH) functions, the method comprising:

(a) the rnc detecting that an eu-sho operation is about to begin; and

(b) in response to step (a), configuring the first mac entity in the rnc to include:

(i) a first generator that generates signals indicating whether an EU transmission generated from the WTRU has been successfully received by the RNC,

(ii) a first uplink scheduler for scheduling eu transmissions of the wtru.

2. The method of claim 1 wherein each eu-sho node-B includes a second mac entity that handles eu-dch functionalities, the second mac entity including hybrid automatic repeat request/automatic repeat request (HARQ/ARQ) communicating with the rnc via a separate signaling channel.

3. The method of claim 1, further comprising:

(c) configuring a second mac entity in a node-B currently operating with the wtru when the wtru soft handover operation is not occurring, comprising:

(i) a second generator for transmitting a signal indicating whether an eu transmission generated from the wtru has been successfully received by the rnc; and

(ii) a second uplink scheduler for scheduling EU transmissions for the WTRU.

4. The method of claim 1 wherein the first uplink scheduler communicates with each eu-sho node-B via an eu frame protocol.

5. A multi-cell wireless communication system supporting eu-sho operations for a wtru, the system comprising:

(a) at least two enhanced uplink soft handover node-bs; and

(b) a radio network controller including a first medium access control entity that handles eu-dch functionality, wherein the radio network controller is configured according to a first architecture when an eu-sho operation of the wtru is not occurring and according to a second architecture when the radio network controller detects that an eu-sho operation of the wtru is about to begin.

6. The system according to claim 5, wherein according to said second architecture, said first mac entity of said rnc comprises:

(a) a first generator that generates signals indicating whether an EU transmission generated from the WTRU has been successfully received by the RNC,

(b) a first uplink scheduler for scheduling eu transmissions of the wtru.

7. The system of claim 5 wherein each eu-sho node-B includes a second mac entity that handles eu-dch functionalities, the second mac entity including hybrid automatic repeat request/automatic repeat request (HARQ/ARQ) communicating with the rnc via a separate signaling channel.

8. The system of claim 6 wherein a second mac entity in a node-B currently operating with the wtru when a soft handover operation of the wtru is not occurring is configured to include:

(i) a second generator for transmitting a signal indicating whether an eu transmission generated from the wtru has been successfully received by the rnc; and

(ii) a second uplink scheduler for scheduling EU transmissions for the WTRU.

9. The system of claim 6 wherein the first uplink scheduler communicates with each eu-sho node-B via an eu frame protocol.

10. A radio network controller, in a multi-cell wireless communication system including a radio network controller, a wtru and at least two eu-sho node-bs in communication with the radio network controller, the radio network controller comprising:

(a) a higher protocol layer; and

(b) a mac entity in communication with the higher protocol layer, wherein the mac entity handles eu-dch functionalities, the rnc is configured according to a first architecture when eu-sho operations of the wtru are not occurring, and according to a second architecture when the rnc detects that eu-sho operations of the wtru are about to begin.

11. The rnc of claim 10 wherein the mac entity comprises according to the second architecture:

(a) a generator that generates a signal indicating whether an EU transmission generated from the WTRU has been successfully received by the RNC,

(b) an uplink scheduler for scheduling EU transmissions for the WTRU.

12. The rnc of claim 11 wherein the uplink scheduler communicates with each eu-sho node-B via an eu frame protocol.

13. In a multi-cell wireless communication system including a radio network controller including at least one Integrated Circuit (IC), a wtru and at least two eu-sho node-bs in communication with the radio network controller, the IC comprising:

(a) a higher protocol layer; and

(b) a mac entity in communication with the higher protocol layer, wherein the mac entity handles eu-dch functionalities, the ic is configured according to a first configuration when an eu-sho operation of the wtru is not occurring, and the ic is configured according to a second configuration when the rnc detects that an eu-sho operation of the wtru is about to begin.

14. The ic of claim 13 wherein the mac entity according to the second architecture comprises:

(a) a generator that generates a signal indicating whether an eu transmission generated from the wtru has been successfully received by the rnc; and

(b) an uplink scheduler for scheduling EU transmissions for the WTRU.

15. The ic of claim 14 wherein the uplink scheduler communicates with each eu-sho node-B via an eu frame protocol.

16. A method for supporting eu-sho operations associated with a wtru in a multi-cell wireless communication system including a rnc and including a first mac entity for handling eu-dch functionality, the method comprising:

(a) the rnc detecting that an eu-sho operation is about to begin; and

(b) during the eu-sho operation, the first mac entity in the rnc generates a signal indicating whether an eu transmission originating from the wtru has been successfully received by the rnc and schedules an eu transmission for the wtru.

17. The method of claim 16 wherein the multi-cell wireless communication system further includes a current node-B in communication with the rnc after completion of the eu-sho operation, the current node-B including a second mac entity that handles eu-dch functionality, the method further comprising:

(c) when an eu-sho operation is not occurring for the wtru, the second mac entity in the current node-B generates a signal indicating whether an eu transmission generated from the wtru has been successfully received by the rnc and schedules eu transmissions for the wtru.