60GHz毫米波WLAN链路维护及定向CCA机制研究
发布时间：2018-08-16 19:10
【摘要】：随着无线局域网技术的快速发展,2.4GHz、5GHz频段已不能满足高速率无线传输对频谱资源的需求,60GHz毫米波频段WLAN关键技术成为未来5G通信的研究热点之一。与2.4GHz、5GHz频段相比,60GHz频段具有更宽的信道和更高的传输速率,但同时也带来了路径损耗大和穿透性差的问题,具有传输距离短、定向传输的特点。由于60GHz毫米波链路传输的方向性,使得全向传输下隐藏终端和暴露终端问题面临新的挑战。此外,IEEE标准组目前正在推进下一代毫米波60GHz频段无线局域网传输标准IEEE 802.11ay,作为2013年订立的IEEE 802.11ad标准的演进。与IEEE802.11ad标准相比,IEEE802.11ay标准具有更高的传输率、支持多用户和一定的移动性,其关键技术包括MU-MIMO和信道绑定。通过采用信道绑定技术,802.11ay中同一对STA和AP节点间可能采用不同带宽的波束赋形(beamformed)链路进行传输。IEEE802.11 ad中定义的单链路有效性维护和指示机制不能满足802.11ay的需求。在IEEE 802.11ad标准定义的链路维护机制基础上,本文进行了改进,提出了一种适用于IEEE 802.11ay的信道绑定机制下同一对节点多条链路有效性指示和维护的方案。具体改进工作包括:首先定义了一种新的beamlinkmaintenance element,以标识及区分不同带宽绑定链路的Timer。其次,针对不同的几种信道绑定链路的建立方式,给出了各个Timer的具体启动时机。此外,针对同一 STA/AP中不同链路的有效性时长的差异性,将802.11ad标准中以节点为单位的Timer冻结和递减原则修改为以链路为单位进行冻结和递减,从而避免由于一条链路的失效而导致所有链路都需要进行重新训练的操作,减少了不必要的训练开销。性能分析及仿真实验验证了本文所提多Timer机制的有效性。针对60GHz毫米波频段WLAN定向传输场景下的隐藏终端和暴露终端的问题,本文提出了一种定向传输下缓解隐藏终端和暴露终端的E-CCA(Enhanced CCA)方案。该方案的主要思路是全向CCA检测和定向CCA检测相结合、发送节点和接收节点都进行CCA检测。将CCA配置与波束方向相关联,使一个CCA配置与节点对数无关,在一个波速方向上只对应一个NAV,以减少NAV设置的冗余,提高效率。并根据信道状态对全向CCA和定向CCA的阈值进行动态设置,来缓解定向隐藏终端和暴露终端问题。性能仿真实验证明E-CCA方案可以在一定程度上降低丢包率,提高网络的平均吞吐量。
[Abstract]:With the rapid development of wireless local area network (WLAN) technology, the 2.4GHz / 5GHz band can no longer meet the demand of high rate wireless transmission for spectrum resources. The key technology of 60GHz millimeter-wave band WLAN has become one of the research hotspots of 5G communication in the future. Compared with 2.4GHz / 5GHz band, the 60GHz band has wider channel and higher transmission rate, but it also brings the problems of high path loss and poor penetration. It has the characteristics of short transmission distance and directional transmission. Due to the directionality of 60GHz millimeter-wave link transmission, hidden terminals and exposed terminals in omnidirectional transmission are facing new challenges. In addition, the IEEE Standard Group is currently promoting the next generation of millimeter-wave 60GHz band WLAN transmission standard IEEE 802.11ayas the evolution of the IEEE 802.11ad standard established in 2013. Compared with the IEEE802.11ad standard, the IEEE 802.11ay standard has higher transmission rate, multi-user support and mobility. Its key technologies include MU-MIMO and channel binding. The single link validity maintenance and indication mechanism defined in IEEE 802.11ad can not meet the requirements of 802.11ay by adopting the channel binding technique and the beamforming (beamformed) link with different bandwidth between the same pair of STA and AP nodes in 802.11ay. Based on the link maintenance mechanism defined by IEEE 802.11ad standard, this paper proposes a scheme for indicating and maintaining the validity of multiple links of the same pair of nodes under the channel binding mechanism suitable for IEEE 802.11ay. The specific improvements include: firstly, a new beamlinkmaintenance element is defined to identify and distinguish timers for different bandwidth-bound links. Secondly, the starting time of each Timer is given according to the different channel binding links. In addition, in view of the difference of the validity time of different links in the same STA/AP, the principle of freezing and decreasing Timer in the 802.11ad standard is modified to freeze and decrease in the unit of link. Therefore, it can avoid the operation that all links need to be retrained because of the failure of one link, thus reducing the unnecessary training cost. Performance analysis and simulation results verify the effectiveness of the proposed multiple Timer mechanism. Aiming at the problem of hidden terminal and exposed terminal in WLAN directional transmission scene of 60GHz millimeter wave band, this paper proposes a E-CCA (Enhanced CCA) scheme to alleviate hidden terminal and exposed terminal under directional transmission. The main idea of this scheme is to combine omnidirectional CCA detection with directional CCA detection, and both sending and receiving nodes perform CCA detection. The CCA configuration is associated with the beam direction, which makes a CCA configuration independent of the node logarithm, and only corresponds to one CCA in the direction of the wave velocity, so as to reduce the redundancy of the NAV configuration and improve the efficiency. The threshold of omnidirectional CCA and directional CCA is set dynamically according to the channel state to alleviate the problem of directional hidden terminal and exposed terminal. The simulation results show that the E-CCA scheme can reduce the packet loss rate to some extent and improve the average throughput of the network.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925.93
本文编号：2186907
[Abstract]:With the rapid development of wireless local area network (WLAN) technology, the 2.4GHz / 5GHz band can no longer meet the demand of high rate wireless transmission for spectrum resources. The key technology of 60GHz millimeter-wave band WLAN has become one of the research hotspots of 5G communication in the future. Compared with 2.4GHz / 5GHz band, the 60GHz band has wider channel and higher transmission rate, but it also brings the problems of high path loss and poor penetration. It has the characteristics of short transmission distance and directional transmission. Due to the directionality of 60GHz millimeter-wave link transmission, hidden terminals and exposed terminals in omnidirectional transmission are facing new challenges. In addition, the IEEE Standard Group is currently promoting the next generation of millimeter-wave 60GHz band WLAN transmission standard IEEE 802.11ayas the evolution of the IEEE 802.11ad standard established in 2013. Compared with the IEEE802.11ad standard, the IEEE 802.11ay standard has higher transmission rate, multi-user support and mobility. Its key technologies include MU-MIMO and channel binding. The single link validity maintenance and indication mechanism defined in IEEE 802.11ad can not meet the requirements of 802.11ay by adopting the channel binding technique and the beamforming (beamformed) link with different bandwidth between the same pair of STA and AP nodes in 802.11ay. Based on the link maintenance mechanism defined by IEEE 802.11ad standard, this paper proposes a scheme for indicating and maintaining the validity of multiple links of the same pair of nodes under the channel binding mechanism suitable for IEEE 802.11ay. The specific improvements include: firstly, a new beamlinkmaintenance element is defined to identify and distinguish timers for different bandwidth-bound links. Secondly, the starting time of each Timer is given according to the different channel binding links. In addition, in view of the difference of the validity time of different links in the same STA/AP, the principle of freezing and decreasing Timer in the 802.11ad standard is modified to freeze and decrease in the unit of link. Therefore, it can avoid the operation that all links need to be retrained because of the failure of one link, thus reducing the unnecessary training cost. Performance analysis and simulation results verify the effectiveness of the proposed multiple Timer mechanism. Aiming at the problem of hidden terminal and exposed terminal in WLAN directional transmission scene of 60GHz millimeter wave band, this paper proposes a E-CCA (Enhanced CCA) scheme to alleviate hidden terminal and exposed terminal under directional transmission. The main idea of this scheme is to combine omnidirectional CCA detection with directional CCA detection, and both sending and receiving nodes perform CCA detection. The CCA configuration is associated with the beam direction, which makes a CCA configuration independent of the node logarithm, and only corresponds to one CCA in the direction of the wave velocity, so as to reduce the redundancy of the NAV configuration and improve the efficiency. The threshold of omnidirectional CCA and directional CCA is set dynamically according to the channel state to alleviate the problem of directional hidden terminal and exposed terminal. The simulation results show that the E-CCA scheme can reduce the packet loss rate to some extent and improve the average throughput of the network.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925.93
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