Browsing by Author "Zhang, Jianzhong"

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    An Efficient Circulant MIMO Equalizer for CDMA Downlink: Algorithm and VLSI Architecture
    (Hindawi Publishing Corporation, 2006-02-01) Guo, Yuanbin; Zhang, Jianzhong; McCain, Dennis; Cavallaro, Joseph R.; Center for Multimedia Communication
    We present an efficient circulant approximation-based MIMO equalizer architecture for the CDMA downlink. This reduces the direct matrix inverse (DMI) of size (NF×NF) with O((NF)3) complexity to some FFT operations with O(NF log2(F)) complexity and the inverse of some (N×N) submatrices.We then propose parallel and pipelined VLSI architectures with Hermitian optimization and reduced-state FFT for further complexity optimization. Generic VLSI architectures are derived for the (4×4) high-order receiver from partitioned (2 × 2) submatrices. This leads to more parallel VLSI design with 3× further complexity reduction. Comparative study with both the conjugate-gradient and DMI algorithms shows very promising performance/complexity tradeoff. VLSI design space in terms of area/time efficiency is explored extensively for layered parallelism and pipelining with a Catapult C high-level-synthesis methodology.
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    Enabling a “Use-or-Share” Framework for PAL–GAA Sharing in CBRS Networks via Reinforcement Learning
    (IEEE, 2019) Tarver, Chance; Tonnemacher, Matthew; Chandrasekhar, Vikram; Chen, Hao; Ng, Boon Loong; Zhang, Jianzhong; Cavallaro, Joseph R.; Camp, Joseph
    By implementing reinforcement learning-aided listen-before-talk (LBT) schemes over a citizens broadband radio service (CBRS) network, we increase the spatial reuse at secondary nodes while minimizing the interference footprint on higher-tier nodes. The federal communications commission encourages “use-or-share” policies in the CBRS band across the priority access license (PAL)-general authorized access (GAA) priority tiers by opportunistically allowing the lower-priority GAA nodes to access unused higher-priority PAL spectrum. However, there is currently no mechanism to enable this cross-tier spectrum sharing. In this paper, we propose and evaluate LBT schemes that allow opportunistic access to PAL spectrum. We find that by allowing LBT in a two carrier, two eNB scenario, we see upward of 50% user perceived throughput (UPT) gains for both eNBs. Furthermore, we examine the use of ${Q}$ -learning to adapt the energy-detection threshold (EDT), combating problematic topologies, such as hidden and exposed nodes. With merely a 4% reduction in primary node UPT, we see up to 350% gains in average secondary node UPT when adapting the EDT of opportunistically transmitting nodes.
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    Structured Parallel Architecture for Displacement MIMO Kalman Equalizer in CDMA Systems
    (IEEE, 2007-02-01) Guo, Yuanbin; Zhang, Jianzhong; McCain, Dennis; Cavallaro, Joseph R.; Center for Multimedia Communication
    A reduced complexity MIMO Kalman equalizer architecture is proposed in this brief by jointly considering the displacement structure and the block-Toeplitz structure. Numerical matrix–matrix multiplications with O(F3) complexity are eliminated by simple data loading process, where is the spreading factor. Finally, an iterative Conjugate-Gradient based algorithm is proposed to avoid the inverse of the Hermitian symmetric innovation covariance matrix in Kalman gain processor. The proposed architecture not only reduces the numerical complexity from O(F2) to O(Flog2F) per chip, but also facilitates the parallel and pipelined VLSI implementation in real-time processing.