Optimized Frameless ALOHA for Cooperative Base Stations With Overlapped Coverage Areas
Optimized Frameless ALOHA for Cooperative Base Stations With Overlapped Coverage Areas
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DOI：
10.1109/twc.2018.2867492
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发表时间：
2017-10
影响因子：
10.4
通讯作者：
Shun Ogata;K. Ishibashi;G. D. de Abreu
中科院分区：
文献类型：
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作者：
Shun Ogata;K. Ishibashi;G. D. de Abreu
在这里，我们考虑的问题，在重叠的覆盖区域的存在下的合作多址接入。假设一个无帧ALOHA传输方案，我们推导出精确的解析吞吐量表达式的吞吐量在上述情况下作为系统的帧长度的函数，并为任意平均数的用户在每个时隙中发送（目标度）。在获得这些原始表达式之后，我们然后用公式表示效用函数，其最大化（例如，通过遗传算法）产生由每个组中的用户采用的不相等的和最优的目标度，以便在满足给定的规定中断的同时最大化整个系统的峰值吞吐量。对优化的单BS无帧ALOHA系统，其中假设在每个BS的用户的完美隔离和平等的最佳目标度为所有用户的合作多基站（BS）多址接入方案的比较表明，在整体吞吐量的显着增益，从而揭示了“多址接入分集增益”可以通过允许来自不同BS的用户组重叠收获。
Herein, we consider the problem of cooperative multi-access in the presence of overlapped coverage areas. Assuming a frameless ALOHA transmission scheme, we derive exact analytical throughput expressions for throughput in the aforementioned scenarios as a function of the frame length of the system and for arbitrary average numbers of users transmitting in each slot (target degree). After obtaining these original expressions, we then formulate a utility function whose maximization (obtained, e.g., through genetic algorithms) yields unequal and optimum target degrees to be employed by users in each group in order to maximize the peak throughput of the whole system while satisfying a given prescribed outage. A comparison of the resulting cooperative multiple base station (BS) multi-access scheme against optimized single-BS frameless ALOHA systems—which presume the perfect isolation of users at each BS and an equal optimum target degree for all users—indicates a significant gain in overall throughput, thereby revealing that a “multi-access diversity gain” can be reaped by allowing groups of users from different BSs to overlap.