User Association for Load Balancing in Heterogeneous Cellular Networks
User Association for Load Balancing in Heterogeneous Cellular Networks
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DOI：
10.1109/twc.2013.040413.120676
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发表时间：
2013-06-01
影响因子：
10.4
通讯作者：
Andrews, Jeffrey G.
中科院分区：
文献类型：
--
作者：
Ye, Qiaoyang;Rong, Beiyu;Andrews, Jeffrey G.
为了使小型蜂窝技术显着提高塔式蜂窝网络的容量，需要积极地将移动用户推向负载较轻的层（对应于微微蜂窝和毫微微蜂窝），即使它们提供的瞬时 SINR 低于宏蜂窝基站 (BS)。优化每个用户的长期速率函数（通常）需要针对所有 SINR 和 BS 负载的大规模效用最大化问题。另一方面，实际实现可能会采用简单的偏置方法，其中第 j 层中的 BS 被视为其 SINR 乘以因子 A(j) >= 1，这使其看起来比重负载宏小区更具吸引力。本文通过网络范围关联问题的几种物理松弛来弥补这些方法之间的差距，该问题的解决方案是 NP 难的。我们提供了一种低复杂度的分布式算法，该算法在理论性能保证的情况下收敛到接近最优的解决方案，并且我们观察到，如果仔细选择偏差值 A(j)，则简单的每层偏差损失惊人地小。数值结果显示，相对于最大化接收功率关联，小区边缘用户的吞吐量增益较大（3.5 倍），中间用户的速率增益为 2 倍。
For small cell technology to significantly increase the capacity of tower-based cellular networks, mobile users will need to be actively pushed onto the more lightly loaded tiers (corresponding to, e.g., pico and femtocells), even if they offer a lower instantaneous SINR than the macrocell base station (BS). Optimizing a function of the long-term rate for each user requires (in general) a massive utility maximization problem over all the SINRs and BS loads. On the other hand, an actual implementation will likely resort to a simple biasing approach where a BS in tier j is treated as having its SINR multiplied by a factor A(j) >= 1, which makes it appear more attractive than the heavily-loaded macrocell. This paper bridges the gap between these approaches through several physical relaxations of the network-wide association problem, whose solution is NP hard. We provide a low-complexity distributed algorithm that converges to a near-optimal solution with a theoretical performance guarantee, and we observe that simple per-tier biasing loses surprisingly little, if the bias values A(j) are chosen carefully. Numerical results show a large (3.5x) throughput gain for cell-edge users and a 2x rate gain for median users relative to a maximizing received power association.