| Millimeter-Wave wireless local area networks (WLAN) and wireless personal area networks (WPAN) that operate in the60GHz band have recently attracted much attention due to their high-data-rate transmission capability. The wireless community has responded to this trend by mobilizing a huge amount of efforts in international standardization activities. Among others, are the IEEE802.15Task Group3c (TG3c) WPAN and the IEEE802.11Task Group ad (TGad).The main function of Medium Access Control (MAC) sublayer is to control devices to access the channel and transmit data. The MAC protocol of mmWave wireless system is different from traditional wireless communication system. One of the leading factors is its high propagation loss. A millimeter-wave communication link imposes more challenges in terms of link budget than those at lower frequencies (e.g.2.4GHz and5GHz bands) because of both its short wavelength and oxygen absorption. In order to overcome the high path loss, directional antennas or beamforming techniques, such as phased antenna arrays, are required in60GHz system. Fortunately, such directional feature due to the large free-space-path-loss opens a window of spatial-reuse in60GHz system, i.e. multiple links working on the same band are allowed to coexist in the same space. On the other hand, due to the short wavelength of mm Wave signal, links are susceptible to obstructions such as walls, ceilings, and the human body, resulting in a time-varying network topology. It is crucial to maintain seamless network connectivity for the stability of the mm Wave links and the achievable system throughput.On examining the commonly envisioned usage models for60GHz systems, it becomes clear that some of the usage scenarios demand heavy exploitation of spatial reuse. In a number of use cases mostly involving enterprise and other public places, it is envisioned that the network topology will be a dense one. This suggest that SDMA (Spatial division multiple access) is an approach to improve system throughput. By employing SDMA, the system has to also incorporate related MAC protocols such as directional device discovery and directional contention access, together with respective MAC overhead. Therefore, in contrary to conventional TDMA system without spatial reuse, the STDMA scheme that allows a time-slot shared by multiple communication links has attracted much attention in60GHz field recently. In mmWave centralized system (e.g., TG3c system, TGad system), it is critical to manipulate various resources such as time, frequency and space.In this paper, we aim to seek for a new scheduling scheme that is simple, and requires minimum overhead. The proposed adaptive STDMA scheduling scheme based on IEEE802.11ad MAC is divided into three main parts:(1) a CCI-monitoring mechanism, in order to measure the potential CCI among all links, we insert a probing signal broadcasting period (PSBP) at the beginning of the DTT and periodically if necessary;(2) a Link-groups-establishing mechanism, The objective of the link-groups-establishing mechanism is find all co-existing link groups based on the level of interference; and (3) an adaptive STDMA Scheduling Algorithm, the objective of the adaptive STDMA scheduling algorithm is to use the least channel time to serve all data flows such that the system throughput is maximized. The additional overhead of the employment of the STDMA scheduling scheme is negligible. The performance of the scheme is evaluated through MATLAB simulations, and compared with the existing VTSA scheduling scheme.In this paper, an anti-blocking scheme using relay going around the obstacles and forwarding data packet was proposed. The proposed scheme based on IEEE802.11ad MAC is divided into two main parts:a fast relay setup mechanism, if the PCP finds that the channel quality of a link has dropped below a threshold (e.g., blocked by a human), the PCP can insert a RLSP before the PSBP in the next BI to find a proper relay for the link; and an adaptive STDMA scheduling algorithm, the adaptive STDMA scheduling algorithm is extended to two-hop network. The additional overhead of the employment of the anti-blocking scheme is negligible. The performance of the scheme is evaluated through MATLAB simulations, and compared with the same scheduling algorithm without relay operation. |
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