Uplink radio access network with uplink scheduling
A radio access network comprises a serving radio network controller (S-RNC). The S-RNC receives successfully received medium access control (MAC) packet data units (PDUs), discards duplicates of MAC PDUs, reorders the non-discarded MAC PDUs based on serial numbers of the MAC PDUs and delivers the MAC PDUs to a radio link control protocol layer. A controlling radio network controller (C-RNC) provides information to Node-Bs under its control for use in scheduling uplink transmissions. A plurality of Node-Bs schedule uplink transmissions in response to the information provided by its C-RNC, transmit scheduling information to user equipments of its cells, receive MAC PDUs from user equipments of its cells using hybrid automatic repeat request and forward the successfully received MAC PDUs to an associated S-RNC.
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This application is a continuation of U.S. patent application Ser. No. 10/939,256, filed Sep. 10, 2004, which claims priority from U.S. Provisional Patent Application Ser. No. 60/517,779, filed Nov. 5, 2003, which is incorporated by reference as if fully set forth herein.
FIELD OF THE INVENTIONThe present invention relates to the field of wireless communications. More specifically, the present invention relates to processing data blocks in a multi-cell wireless communication system, such as a frequency division duplex (FDD) or time division duplex (TDD) system.
BACKGROUNDMethods for improving uplink coverage, throughput and transmission latency are currently being investigated in third generation partnership project (3GPP) in the context of the Release 6 (R6) universal mobile telecommunications system (UMTS) study item “FDD uplink enhancements”.
It is widely anticipated that in order to achieve these goals, Node-B (base station) will take over the responsibility of scheduling and assigning uplink resources (physical channels) to users. The principle is that Node-B can make more efficient decisions and manage uplink radio resources on a short-term basis better than the radio network controller (RNC), even if the RNC retains coarse overall control. A similar approach has already been adopted in the downlink for Release 5 (R5) high speed downlink packet access (HSDPA) in both UMTS FDD and TDD modes.
It is also envisioned there could be several independent uplink transmissions processed between a wireless transmit/receive unit (WTRU) and a universal terrestrial radio access network (UTRAN) within a common time interval. One example of this would be medium access control (MAC) layer hybrid automatic repeat request (HARQ) or simply MAC layer automatic repeat request (ARQ) operation where each individual transmission may require a different number of retransmissions to be successfully received by UTRAN. To limit the impact on system architecture, it is expected that protocol layers above the MAC should not be affected by introduction of the enhanced uplink dedicated channel (EU-DCH). One requirement that is introduced by this is the in-sequence data delivery to the radio link control (RLC) protocol layer. Therefore, similar to HSDPA operation in the downlink, a UTRAN re-ordering function is needed to organize the received data blocks according to the sequence generated by the WTRU RLC entity.
A soft handover macro-diversity operation requires centralized control of uplink transmissions in each cell within an active set. The active set may include a plurality of Node-Bs. Retransmissions are generated until successful transmission is realized by at least one of the Node-Bs. Successful transmission is not guaranteed at all of the Node-Bs. Therefore, since a complete set of successful transmissions may not be available within any one Node-B, re-ordering of successful transmissions cannot be accomplished.
SUMMARYA radio access network comprises a serving radio network controller (S-RNC). The S-RNC receives successfully received medium access control (MAC) packet data units (PDUs), discards duplicates of MAC PDUs, reorders the non-discarded MAC PDUs based on serial numbers of the MAC PDUs and delivers the MAC PDUs to a radio link control protocol layer. A controlling radio network controller (C-RNC) provides information to Node-Bs under its control for use in scheduling uplink transmissions. A plurality of Node-Bs schedule uplink transmissions in response to the information provided by its C-RNC, transmit scheduling information to user equipments of its cells, receive MAC PDUs from user equipments of its cells using hybrid automatic repeat request and forward the successfully received MAC PDUs to an associated S-RNC.
BRIEF DESCRIPTION OF THE DRAWING(S)A more detailed understanding of the invention may be had from the following description of a preferred embodiment, given by way of example, and to be understood in conjunction with the accompanying drawings wherein:
The present invention will be described with reference to the drawing figures wherein like numerals represent like elements throughout.
Hereafter, the terminology “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. When referred to hereafter, the terminology “base station” includes but is not limited to a Node-B, a site controller, an access point or any other type of interfacing device in a wireless environment.
The present invention may be further applicable to TDD, FDD, and time division synchronous code division multiple access (TD-SCDMA), as applied to UMTS, CDMA 2000 and CDMA in general, but is envisaged to be applicable to other wireless systems as well. With respect to CDMA2000, the present invention may be implemented in EV-DO (i.e., data only) and EV-DV (i.e., data and voice).
The features of the present invention may be incorporated into an IC or be configured in a circuit comprising a multitude of interconnecting components.
During soft handover, higher layers maintain an active subset of EU cells for which EU-DCHs are maintained in a soft handover macro diversity state. Those cells in the active subset may be controlled by different EU-SHO Node-Bs.
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If step 225 determines that multiple copies of the successfully decoded data block are received from different EU-SHO Node-Bs 110, only one copy will be stored in a re-ordering buffer (not shown) maintained by a re-ordering function entity 115 in the S-RNC 105 as a correctly received data block, and any extra received copies of the successfully decoded data block are discarded as redundant data (step 230).
Finally, in step 235, the successfully decoded data block is processed by the re-ordering function entity 115 in the S-RNC 105. The re-ordering function entity 115 in the S-RNC 105 performs a re-ordering procedure on those successfully decoded data blocks that are correctly received in the re-ordering function entity 115 so as to support in-sequence delivery to the higher protocol layers 125.
Process 200 is beneficial because data blocks received from different EU-SHO Node-Bs 110 can be combined and organized in-sequence for delivery to the higher protocol layers 125 of the S-RNC 105. The re-ordering function entity 115 located within the S-RNC 105 allows enhanced uplink MAC PDU's to be processed for successful reception and proper delivery to higher layers independent of which Node-B(s) that provided reception of each PDU, resulting in the reduction of loss of MAC data and RLC recoveries.
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If, in step 415, it is determined that at least one copy of a successfully decoded data block has been received by the C-RNC 305 from an EU-SHO Node-B 310, a determination is then made as to whether or not multiple copies of the successfully decoded data block are received from different EU-SHO Node-Bs 110 (step 425).
If step 425 determines that multiple copies of the successfully decoded data block are received from different EU-SHO Node-Bs 310, only one copy will be stored in a re-ordering buffer (not shown) maintained by a re-ordering function entity 315 in the C-RNC 305 as a correctly received data block, and any extra received copies of the successfully decoded data block are discarded as redundant data (step 430).
Finally, in step 435, the successfully decoded data block is processed by the re-ordering function entity 315 in the C-RNC 305, which performs a re-ordering procedure on those successfully decoded data blocks that are correctly received in the re-ordering function entity 315 so as to support in-sequence delivery to the higher protocol layers 325.
Process 400 is beneficial because data blocks received from different EU-SHO Node-Bs 310 can be combined and organized in sequence for delivery to the higher protocol layers 325, provided that these Node-Bs 310 have the same C-RNC 305. This is frequently the case, although its applicability is somewhat more restrictive than placing a re-ordering function in an S-RNC 105. However, this restriction is offset by other considerations. For example, a benefit of C-RNC operation is reduced latency for H-ARQ operation. The performance benefits of minimizing this latency are well understood in the art. During soft handover, it is also desirable to have a common uplink scheduler in the C-RNC 305 for all of the cells that are in the active EU subset, including cells that are controlled by different Node-Bs 310.
While this invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention described hereinabove.
Claims
1. A radio access network comprising:
- a serving radio network controller (S-RNC) receives successfully received medium access control (MAC) packet data units (PDUs), discards duplicates of MAC PDUs, reorders the non-discarded MAC PDUs based on serial numbers of the MAC PDUs and delivers the MAC PDUs to a radio link control protocol layer;
- a controlling radio network controller (C-RNC) provides information to Node-Bs under its control for use in scheduling uplink transmissions; and
- a plurality of Node-Bs, each Node-B schedules uplink transmissions in response to the information provided by its C-RNC, transmits scheduling information to user equipments of its cells, receives MAC PDUs from user equipments of its cells using hybrid automatic repeat request and forwards the successfully received MAC PDUs to an associated S-RNC.
2. The radio access network of claim 1 wherein each Node-B checks a cyclic redundancy check of the MAC PDUs to determine whether the MAC PDU was received successfully.
3. The radio access network of claim 1 wherein only successfully received MAC PDUs are forwarded to the S-RNC.
Type: Application
Filed: Apr 6, 2007
Publication Date: Aug 9, 2007
Applicant: InterDigital Technology Corporation (Wilmington, DE)
Inventors: Guodong Zhang (Farmingdale, NY), Stephen Terry (Northport, NY), Stephen Dick (Nesconset, NY)
Application Number: 11/784,336
International Classification: H04Q 7/20 (20060101);