IEEE C802.16m-08/1031 Project IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16> Title Uplink Data Transmission for IEEE 802.16m Date Submitted 2008-09-05 Source(s) Yih-Shen Chen, Kelvin Chou, I-Kang Fu and Paul Cheng Yihshen.Chen@mediatek.com Kelvin.Chou@mediatek.com IK.Fu@mediatek.com MediaTek Inc. Re: MAC: Data Plane; in response to the TGm Call for Contributions and Comments 802.16m-08/033 for Session 57 Abstract This contribution discusses grant allocation and scheduling for uplink data transmission Purpose To be discussed and adopted by TGm for the P802.16m SDD. Notice Release Patent Policy This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. 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Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and <http://standards.ieee.org/board/pat>. 1 IEEE C802.16m-08/1031 Uplink Data Transmission for IEEE 802.16m Yih-Shen Chen, Kelvin Chou, I-Kang Fu, and Paul Cheng MediaTek Inc. 1. Introduction In 802.16 system, the uplink transmission starts from the request-and-grant negotiation. Mobile station (MS) may establish multiple uplink connections with its serving base station (BS), and each connection has its specific quality of service (QoS) parameter set. Based on the QoS parameters and buffer status, the MS makes transmission request via contention-based or polling-based bandwidth request (BR) attempt. And then, the BS grants uplink transmission resource to the MS. In legacy system, the BR is made per connection and the grant is per terminal. SRD states that IEEE 802.16m shall support different QoS levels for different services [1]. However, in the legacy system, there is no scheduling rule commonly known between BS and MS. The BS performs its specific scheduling algorithm to distribute the UL bandwidth between multiple connections/BSs, and the BS has to “guess” the allocation rule by itself. Consequently, there would be a serious QoS issue when MS sends multiple BRs because the MS is not aware which connections are honored by the BS and how the bandwidth are shared among the connections. Four scheduling types are defined for 802.16 legacy systems, including: unsolicited grant service (UGS), realtime polling service (rtPS), non-real-time polling service (nrtPS) and best effort services (BE). For UGS and rtPS, BS periodically grants UL transmission bandwidth. For nrtPS and BE, BS grants UL transmission bandwidth upon the reception of BRs. Since there is no strict time constraint between the request and grant messages, BS may possibly collect multiple connection requests to handle. In legacy system, the grant message only includes two parameters: Basic CID and transmission attribute. As mentioned, the grant is given per terminal. Without any explicit indication, it’s hard for the MS to efficiently multiplex packets from multiple connections into a single transmission block. In the contribution, for finer QoS control, we propose a 2-step uplink resource allocation scheme for IEEE 802.16m system. In the 2-step scheme, BS announces the uplink bandwidth allocation by class-based grant message and MS multiplexes packets from multiple connections by pre-defined scheduling principles. 2 IEEE C802.16m-08/1031 2. Class-based uplink resource grant The proposed grant message consists of class indication as well as Basic CID and transmission attribute. The class indication is used to specify what kinds of scheduling type are to be transmitted in the uplink resource. An uplink resource grant may be used to multiplex multiple connections from a single or multiple scheduling types. Therefore, it is possible to use a bitmap for the class indication, where each bit represents a specific scheduling type. The resource allocation and multiplexing of connections from different scheduling types is up to BS’ implementation. BS makes the allocation based on connections’ QoS requirements and BRs. Noted that, the time latency and BLER requirements are very different for data-plane and control-plane (MAC management messages) transmissions; therefore, it is recommended not to multiplex them into a single UL resource block. 3. Uplink scheduling principles Within the same scheduling type, pre-defined scheduling principles are applied by MS. In this contribution, we recommend that some common uplink scheduling rules shall be defined for 802.16m systems. These scheduling rules are used to fulfill the QoS requirements. In SRD, it is said that IMT-Advanced QoS requirements shall be supported including end-to-end latency, throughput, and error performance [1]. To meet the requirements, there are many applicable scheduling rules. Priority-based uplink scheduling rule with minimum rate is one of the possible algorithms. In the priority-based scheduling scheme, the low-latency connections may be assigned with a higher priority to utilize uplink bandwidth so as to reduce transmission delay while the minimum-rate parameter may be used to guarantee a sustainable throughput. The detail design of pre-defined uplink scheduling rules is FFS. 4. Proposed Text for SDD [Add section 10.4 uplink transmission scheduling in TGm SDD[1], ] ------------------------------- Text Start ---------------------------------------------------------------------------------10.4 uplink transmission scheduling For QoS control, a 2-step uplink resource allocation scheme is considered in IEEE 802.16m system. In the 2step scheme, BS announces the uplink bandwidth allocation by class-based grant message and MS multiplexes packets from multiple connections by pre-defined scheduling principles. The grant message consists of class indication as well as Basic CID and transmission attribute. The class indication is used to specify what kinds of scheduling type are to be transmitted in the uplink resource. And, for uplink transmission, some common uplink scheduling rules shall be defined for 802.16m systems so as to fulfill the IMT-Advanced QoS requirements. ------------------------------- Text End -----------------------------------------------------------------------------------[1] IEEE 802.16m-08/003r4, “The Draft IEEE 802.16m System Description Document” 3