Multimedia streaming applications with stringent QoS requirements in 60GHz mmWave wireless personal area networks (WPANs) demand high rate and low latency data transfer as well as low service disruption. In this paper, we consider the problem of robust relay placement in 60GHz WPANs. Relays forward traffic from transmitter devices to receiver devices facilitating i) the primary communication path for non-line-of-sight (NLOS) transceiver pairs, and ii) secondary (backup) communication path for line-of-sight (LOS) transceiver pairs. We formulate the robust minimum relay placement problem and the robust maximum utility relay placement problem with the objective to minimize the number of relays deployed and maximize the network utility, respectively. Efficient algorithms are developed to solve both problems and have been shown to incur less service disruption in presence of moving subjects that may block the LOS paths in the environment.
There are also some existing work on repeater selection and relay operation scheduling in mmWave WPANs. Repeater selection was investigated in @cite_29 , with the objective to maximize data rate for each transmitter and receiver pair by determining the best link allocation. @cite_6 , Lan explored time slot scheduling for relay operations in the scenario of directional antenna on mmWave devices and formulated the throughput maximization problem as an integer programming problem. However, both schemes do not consider robustness in presence of uncertain link blockage.
@cite_29 @cite_6
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In this paper, we propose a spacial time slot scheduling algorithm for relay operation to improve the throughput performance of millimeter-wave wireless personal area network (mmWave WPAN) systems which employ directional antenna. The upcoming mmWave WPAN is designed for high definition TV (HDTV) transmission, high speed wireless docking and gaming, etc. Based on the fact that the significant path loss of millimeter-wave environments provides good space isolation, we have proposed a coexistence mechanism by sharing time slots for relay with direct transmission to guarantee throughput for the above data-rate-greedy applications. This paper is an extension that addresses spacial time slot scheduling for relay operation taking the effect of directional antenna into consideration. We model the throughput maximization with scheduling as an integer optimization and solve it by transforming the problem to a max-weight matching problem of a bipartite graph. We propose a scheduling algorithm based on the Kuhn-Munkres algorithm which can be used to solve the max weight matching problem. Simulation results show that there is up to 25 throughput improvement achieved compared with random scheduling method. With the increase in emerging bandwidth-intensive applications, millimeter-wave (mmWave) communications in 60-GHz band have become a hot topic. There are two unique features that sharply distinguish mmWave wireless personal area networks (WPANs) from other networks using lower carrier frequencies. First, mmWave links use high-gain directional antennas to overcome the high propagation loss. Second, mmWave links are easily blocked by the human body and furniture. In this paper, we develop a blockage robust and efficient directional medium access control (MAC) protocol (BRDMAC), which overcomes the blockage problem by relaying. Relay selection and spatial reuse are jointly optimized to improve network performance. In BRDMAC, relay selection and transmission scheduling algorithms are proposed to compute near-optimal relay selection to maximize spatial reuse and compute near-optimal schedules with respect to the total transmission time, respectively. Finally, extensive simulation results show that BRDMAC performs better in terms of delay and throughput, compared with other existing protocols while attaining a good fairness performance.