Joint Downlink Cell Association and Bandwidth Allocation for Wireless Backhauling in Two-Tier HetNets With Large-Scale Antenna Arrays
Joint Downlink Cell Association and Bandwidth Allocation for Wireless Backhauling in Two-Tier HetNets With Large-Scale Antenna Arrays
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DOI：
10.1109/twc.2016.2519401
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发表时间：
2014-12
影响因子：
10.4
通讯作者：
Ning Wang;E. Hossain;V. Bhargava
中科院分区：
文献类型：
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作者：
Ning Wang;E. Hossain;V. Bhargava
研究了两层蜂窝异构网络（HetNets）中的联合下行小区关联（CA）和无线回程带宽分配（WBBA）问题。在宏基站（BS）处实现大规模天线阵列，而宏小区范围内的小小区是单天线BS，并且它们依赖于到宏BS的空中链路以用于回程。研究了无线回程约束下的和对数用户速率最大化问题。考虑双工和与同信道反向时分双工（TDD）和动态软频率重用的频谱共享，用于在宏BS处采用大规模天线阵列和用于小小区的无线回程的双层HetNet中的干扰管理。针对HetNet中的联合CA-WBBA，研究了两种带内WBBA场景，即统一带宽分配和每个小小区带宽分配。采用一种两层递阶松弛优化分解方法求解混合整数非线性规划问题。基于通用算法建模系统（GAMS）优化求解器和快速算法的解决方案也提出了在每小小区WBBA场景中的小区关联。结果表明，当所有的小小区都必须使用带内无线回程时，系统负载对总对数速率和每用户速率性能的影响大于部署在宏小区范围内的小小区的数量。所提出的联合CA-WBBA算法具有近似等于宏BS处的大规模天线阵列的大小的最优负载。小区范围扩展（CRE）策略是具有理想回程的HetNet的有效小区关联方案，当用于小小区的带内无线回程开始起作用时，该策略被示出为效率低下。
The problem of joint downlink cell association (CA) and wireless backhaul bandwidth allocation (WBBA) in two-tier cellular heterogeneous networks (HetNets) is investigated. Large-scale antenna array is implemented at the macro base station (BS), while the small cells within the macro cell range are single-antenna BSs and they rely on over-the-air links to the macro BS for backhauling. A sum logarithmic user rate maximization problem is studied under the wireless backhaul constraints. Duplex and spectrum sharing with co-channel reverse time-division duplex (TDD) and dynamic soft frequency reuse is considered for interference management in the two-tier HetNet employing large-scale antenna arrays at the macro BS and wireless backhauling for small cells. Two in-band WBBA scenarios, namely, unified bandwidth allocation and per-small-cell bandwidth allocation, are investigated for joint CA-WBBA in the HetNet. A two-level hierarchical decomposition method for relaxed optimization is employed to solve the mixed-integer nonlinear program (MINLP). Solutions based on the General Algorithm Modeling System (GAMS) optimization solver and fast heuristics are also proposed for cell association in the per-small-cell WBBA scenario. It is shown that when all small cells have to use in-band wireless backhaul, the system load has more impact on both the sum logarithmic rate and per-user rate performance than the number of small cells deployed within the macro cell range. The proposed joint CA-WBBA algorithms have an optimal load approximately equal to the size of the large-scale antenna array at the macro BS. The cell range expansion (CRE) strategy, which is an efficient cell association scheme for HetNets with ideal backhauling, is shown to be inefficient when in-band wireless backhauling for small cells comes into play.