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Meeting Report. Gill Aug. 24, 2010. Letter -- simulation. Sum rate. DIA-MMSE. DIA-MMSE: Since DIA is suboptimal, it should be operated for Tx first, then MMSE for Rx during each iteration. Letter -- simulation (cont.). 4 ×4 3 links. Letter -- simulation (cont.). 3 ×3 3 links.
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Meeting Report Gill Aug. 24, 2010
Letter -- simulation Sum rate DIA-MMSE • DIA-MMSE: Since DIA is suboptimal, it should be operated for Tx first, then MMSE for Rx during each iteration.
Letter -- simulation (cont.) 4×4 3 links
Letter -- simulation (cont.) 3×3 3 links • Which case to choose in the letter? • {3x3, 3} or/and {4x4, 3}?
Letter – Larry’s comments • Title: A new distributed interference alignment algorithm for multiuser MIMO networks. • Should “Max SNR” be added in the title? Compared with ML-DIA, this is the main improvement of MS-DIA. • One of old algorithms, named as Max-SINR or MMSE? • The classification in section III (algorithm description part): 3 or 4 subsections? • The contribution of the letter • Compared with ML-DIA, MS-DIA has better performance. • Compared with MMSE, MS-DIA has faster convergence.
Distributed Power Control and Interference Alignment for MIMO BC Networks
System model MIMO-BC Motivation Larry: use different SNRs for each link, taking path loss and errors in the channel into account. Doug: MIMO-BC and MIMO-MAC are realistic cases in 802.11ac. Power constraints of the network.
System model (cont.) • Downlink network (original network) • BS/AP with M antennas • K users with Nk antennas and one data stream each • DL channel: • SINR of the kth stream/user: • Uplink network (dual network) • SINR of the kth stream/user: • Problem to solve: beamformer and power optimization.
General algorithm – BF&PC • Step 1: consider downlink channel with fixed and given qk and Vk • Update vector pk by a certain power control method • Optimize vector Uk by beamforming method. • Step 2: consider uplink channel with fixed and given pk and Uk • Update qk by a power control method • Optimize vector Vk by beamforming method. • Step 3: test a stopping criterion • Beamforming method: IA, ZF, MMSE. • Power control method: waterfilling, binary power control, pricing algorithm, etc. • Convergence of iterative method: monotonic increase of SINR with a bound.
Simulation • Case 1: {4x4, 3} • AP with 4 Tx antennas • 3 users with 4 Rx antenna each • Case 2: {3x3, 2} • AP with 3 Tx antennas • 2 users with 3 Rx antenna each • Single SS per user in the MU-MIMO • Uniform power allocation • Results for 2000 channel realizations • Iterative algorithms • MMSE: done to beam-form the 1 SS of each user • MS-DIA
Simulation & discussion 4×4 3 links 3×3 2 links • As optimal filter, MMSE is widely used for BF&PC in literature. • MS-DIA achieves the same performance as MMSE at high SNR. (Similar to MIMO X Channel) • The difference between MIMO-BC/MAC and MIMO X Channel?