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摘要:
针对在随机接入中由于碰撞导致吞吐率低、信道拥塞时不能满足高优先级数据有效传输的问题,提出一种具有不等差错保护性能的多用户随机接入方法。该方法将数据包复制多份,根据选定的度分布在不同时隙中传输,将随机接入过程映射到二分图上;接收端利用连续干扰消除(SIC)技术,将碰撞的数据包恢复出来。在高链路负载下,从每帧中选取若干时隙,只允许高优先级用户接入,以提高对高优先级数据包的译码概率。使用“与或树”理论对提出的方法进行了理论分析,并进行了实验仿真验证。仿真结果表明:提出的多用户随机接入方法与传统ALOHA协议相比,在低链路负载下有效避免由于碰撞引起的吞吐率下降;与IRSA协议相比,高链路负载下有效提高高优先级用户的吞吐率。
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关键词:
- 随机接入 /
- 不等差错保护 /
- 时隙ALOHA /
- 连续干扰消除(SIC) /
- IRSA
Abstract:The throughput performance degrades under high traffic loads when massive bursty users have access to the satellite. To solve this problem, a random multi-user access method with unequal protection was proposed. Several copies of a packet were created and sent during different time slots according to a selected degree distribution. The random access procedure could be described by a bipartite graph. By using successive interference cancellation (SIC), collided packets can be recovered instead of abandoned. In addition, a portion of time slots in each frame were selected exclusively for high-priority users to improve the decoding probability of high-priority data packet. An analysis using standard "and-or trees" theory was introduced. Further, the proposed method was verified with experimental simulations. The simulation results show that the proposed random multi-user access method, compared with traditional ALOHA protocol, effectively avoids the throughput degradation caused by impact under low traffic loads. Compared with IRSA protocol, it enhances high-priority users' throughput under high traffic loads.
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Key words:
- random access /
- unequal protection /
- slotted ALOHA /
- successive interference cancellation (SIC) /
- IRSA
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表 1 链路负载估计均值和方差
Table 1. Traffic load estimate mean and variance
负载 均值 均方差 0.2 0.200 0.007 0.4 0.400 0.013 0.6 0.601 0.017 0.8 0.799 0.025 1.0 1.006 0.038 1.2 1.203 0.053 1.4 1.408 0.080 1.6 1.616 0.119 1.8 1.824 1.954 2.0 0.140 0.165 -
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