Utilization of LTE-a uplink resource for cognitive radio network via matching and quantizing

With the development of next generation mobile communications, the underlay coexistence problem of the OFDMA based Secondary System(SS) with LTE-A systems becomes more and more important, which yet has not been studied in a systematic way. In contrast to other Primary Systems(PS), the LTE-A system puts high demands on the low complexity of the coexistence strategies. This paper focuses on the resource allocation and interference mitigation issues in the aforementioned scenario, whose objective is to protect the spectrum utilization priority of PS as well as utilize secondary resource efficiently. The difficulty lies in the fact that even the subproblem, or power allocation with interference, is NP-Hard. Therefore, this paper will propose a two-phase resource allocation algorithm using maximum weighted Matching in the subcarrier allocation phase and interference Quantizing in the power allocation phase, referred to as the MQ algorithm. As presented in this paper, the MQ algorithm enjoys the advantage of polynomial complexity of O(KJ³ + LKJ), where K, J and L denote the number of SSs, subcarriers and quantizing steps, respectively. The simulation results will show that the proposed MQ algorithm is capable of achieving near optimal system and user throughputs, which are close to the exhaustive searching algorithm.