IEEE 802.15.6 is the first international Wireless Body Area Network (WBAN) standard that supports communications in the vicinity of or inside a human body to serve a variety of medical and nonmedical applications. The standard defines a Medium Access Control (MAC) layer that supports several Physical (PHY) layers. In this paper, the key features of the IEEE 802.15.6 standard are presented. The MAC, PHY, and security specifications of the standard are explained in detail. Different communication modes and access mechanisms are presented. The Narrowband (NB), Ultra-wideband (UWB), and Human Body Communications (HBC) specifications are reviewed in terms of frame structure, modulation, and other important parameters. Finally, the security paradigm and services of the standard are highlighted.
Block diagonalization (BD) is an attractive technique that transforms the multi-user multiple-input multipleoutput (MU-MIMO) channel into parallel single-user MIMO (SU-MIMO) channels with zero inter-user interference (IUI). In this paper, we combine the BD technique with two deterministic vector perturbation (VP) algorithms that reduce the transmit power in MU-MIMO systems with linear precoding. These techniques are the fixed-complexity sphere encoder (FSE) and the QR-decomposition with M-algorithm encoder (QRDM-E). In contrast to the conventional BD VP technique, which is based on the sphere encoder (SE), the proposed techniques have fixed complexity and a tradeoff between performance and complexity can be achieved by controlling the size of the set of candidates for the perturbation vector. Simulation results and analysis demonstrate the properness of the proposed techniques for the next generation mobile communications systems which are latency and computational complexity limited. In MU-MIMO system with 4 users each equipped with 2 receive antennas, simulation results show that the proposed BD-FSE and BD-QRDM-E outperforms the conventional BD-THP (Tomlinson Harashima precoding) by 5.5 and 7.4dB, respectively, at a target BER of 10 −4 .
Abstract:In this paper, we propose a fixed-complexity sphere encoder (FSE) for multi-user MIMO (MU-MIMO) systems. The proposed FSE accomplishes a scalable tradeoff between performance and complexity. Also, because it has a parallel tree-search structure, the proposed encoder can be easily pipelined, leading to a tremendous reduction in the precoding latency. The complexity of the proposed encoder is also analyzed, and we propose two techniques that reduce it. Simulation and analytical results demonstrate that in a 4×4 MU-MIMO system, the proposed FSE requires only 11.5% of the computational complexity needed by the conventional QRD-M encoder (QRDM-E). Also, the encoding throughput of the proposed encoder is 7.5 times that of the QRDM-E with tolerable degradation in the BER performance, while achieving the optimum diversity order.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.