Protocol Design and Resource Allocation for LTE-U System Utilizing Licensed and Unlicensed Bands

• Published in: IEEE access Vol. 7; pp. 67068 - 67080
• Main Authors: Wu, Weihua, Yang, Qinghai, Liu, Runzi, Kwak, Kyung Sup
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Approximation; coexistence protocol; Devices; Iterative methods; LBT; Licenses; Long Term Evolution; LTE-unlicensed bands; Markov chains; Mathematical analysis; Multiple objective analysis; Optimization; Power control; Protocols; Resource allocation; Resource management; Throughput; Wireless communications; Wireless networks
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2019.2917692

LTE deployed with both licensed and unlicensed bands (LTE-U) is one of the promising approaches to meet the rapidly growing data demand in wireless networks. In this paper, both throughput and fairness for the LTE-U system are maximized by a multi-objective optimization problem. Then, a log-sum-exp approximation method is developed to convert the multi-objective optimization into a single objective optimization problem. At the same time, the tradeoff between throughput and fairness is mathematically depicted by a control parameter. To tackle the obtained single objective optimization problem, a Markov chain directed algorithm is developed to convert it into a coexistence protocol design subproblem at the MAC layer and a resource allocation subproblem at the physical layer, respectively. Then, we propose adaptive exponential backoff schemes for both the LTE-U devices and the incumbent devices on the unlicensed bands. After that, a low-complexity two-iterative optimization procedure is developed to jointly allocate the licensed and unlicensed resources of the LTE-U system. The simulation results show that our proposed coexistence protocol and resource allocation can achieve fair coexistence between the LTE-U devices and the incumbent devices on the unlicensed bands, moreover it can achieve higher throughput than the non-adaptive coexistence protocol in the unlicensed bands.