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Proposal for Inter-cell Multiple Access Scheme in 802.16m Downlink. Zhou Shidong, Li Yunzhou Tsinghua University. Content. Non-orthogonal downlink resource allocation among adjacent cells/sectors Requirement of resource allocation criterion. Physical resource allocation of downlink.
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Proposal for Inter-cell Multiple Access Scheme in 802.16m Downlink Zhou Shidong, Li Yunzhou Tsinghua University
Content • Non-orthogonal downlink resource allocation among adjacent cells/sectors • Requirement of resource allocation criterion
Physical resource allocation of downlink • Multiuser resource allocation within each cell • Orthogonal allocation is highly recommended, i.e., OFDMA, • both in time domain and frequency domain • In special cases, non-orthogonal allocation can also be included • Superposition coding for making full use of near-far effect • Multi-cell resource allocation between adjacent cells • Fractional frequency reuse can be applied • At the cell edge, when traffic is light, orthogonal allocation is highly recommended • At the cell edge, when traffic is heavy, non-orthogonal resource allocation (time/frequency reusing) among adjacent cells will be included, e.g., CDMA, IDMA (interleaver divistion multiple access)
Spectrum segmentation for downlink physical resource allocation at the cell edge • Different resource blocks (chunks) can be allocated to adjacent cells • A separate segment of resource blocks is to be assigned for the use of IDMA • This region can be further divided into subzones, for different kinds of resource reuse • Benefit of IDMA • Provide more users served at cell edge • Provide higher data rate with joint decoding at cell edge.
Requirement on non-orthogonal resource allocation • When only single-user-decoding is applied with IDMA, • no additional restriction of resource allocation • When some of the terminals at cell edge need to perform joint decoding with adjacent cell users • Resource allocation alignment is recommended • For simple implementation With resource alignment, joint decoding can be local ones Without resource alignment, joint decoding should be global
Proposed SDD Text (1) • x.x Downlink and Uplink Multiple Access Schemes • IEEE 802.16m usesOFDMAas the downlink intra-cell/sector multiple access scheme. • As for downlink inter-cell/sector multiple access schemes, besides orthogonal(time/frequency) multiple access among adjacent cells/sectors where cell/sector edge traffic is not very heavy, non-orthogonal multiple access shall be included for heavy traffic as cell/sector edge, when adjacent cells/sectors can use the same frequency/time resource simultaneously. • As an additional non-orthogonal multiple access technique, IDMA is used to support higher rate for users at cell/sector edge.
Proposed SDD Text (2) • x.x Downlink Physical Resource Allocation Unit • When non-orthogonal downlink multiple access among adjacent cells/sectors is to be applied for downlink resource allocation, a segment for non-orthogonal resource allocation shall be defined, which is better to be aligned with adjacent cells/sectors. The allocation of such resource segment among users shall support resource unit alignment among usersfrom adjacent cells/sectors which may share the resource.