可避免用户冲突的OFDMA下行链路资源分配方案

Resource allocation for OFDMA downlink system with user conflict avoidance mechanism

针对单小区全双工正交频分多址(OFDMA)系统下行链路多子载波多用户分配时可能产生的用户冲突问题,同时考虑子载波复用所带来的上下行链路干扰,提出一种可有效解决用户冲突且缓解上下行链路干扰的自适应资源分配方案。该方案结合改进贪婪算法的子载波分配和基于迭代注水算法的功率分配来实现子载波-功率联合优化调度。用二分法找出各子载波可供分配的下行用户集,再在等发射功率下选择各子载波对应集合中信干噪比最高的用户,若匹配到同一用户,选择提供更大速率的子载波来匹配。最后提出改进迭代注水算法来分配功率。仿真结果表明,相比已有资源分配方案,文中所提方案解决了子载波分配中用户冲突问题,提升了功率分配效率,在兼顾用户公平性的同时有效提高OFDMA系统下行链路总吞吐量。

Aiming at the user conflict problems for assigning multiple subcarriers among multiple users in the single-cell full-duplex orthogonal frequency division multiple access(OFDMA)downlink system,and considering the interference between uplink and downlink due to subcarrier multiplexing,an adaptive resource allocation scheme for resolving above both issues is proposed.The scheme combines the subcarrier allocation with a greedy algorithm and the power allocation with a iterative water-filling algorithm to solve the optimization problem of the subcarrier and the power joint distribution.The downlink user set for each subcarrier is found by the dichotomy method.Each subcarrier is primarily assigned to the user with the highest signal-to-interference-and-noise-ratio(SINR)on the assumption of the equivalent transmitted power.If one user may be matched to more than one subcarrier,the subcarrier with a larger rate is selected.Finally,a feasible optimal power distribution scheme is obtained by an improved iterative water injection algorithm.Simulation results show that,compared with existing resource allocation schemes,the scheme resolves the user conflict in the subcarrier allocation,thus improving the efficiency of the power distribution and the throughput of the downlink system while considering user fairness.