Research On The Cross-layer Dynamic Subcarrier Allocation In SC-FDMA System

The rapid innovation of mobile communication network promotes the flourishingdevelopment of multimedia technology, and also causes a increasingly outstandingcontradiction between the limited frequency resources and the growing user service demands.With the gradual perfection of standardization work in Long Term Evolution (LTE), theexploitation of the radio resource management mode has become the focus of the informationindustry. Therefore, as an effective technique for frequency resources scheduling, DynamicSubcarrier Allocation (DSA) is now wildly studied and employed in both the uplink anddownlink LTE system due to its high system frequency efficiency performance and excellentquality of service (QoS) provisioning capability in multi-service environment.This paper focuses on cross-layer DSA of the Single Carrier Frequency DivisionMultiple Access (SC-FDMA) system, it mainly includes:Firstly, the non-real-time traffic oriented DSA problem for the SC-FDMA system isanalyzed. Based on the single non-real-time traffic model, maximum average capacity DSAalgorithm is proposed. The main idea of the proposed algorithm is to maximize the averagecapacity of system users without taking the searching process with respect to all the systemusers and resource blocks in traditional greedy algorithm, thereby achieving high systemfrequency efficiency performance with low computational complexity. And for meeting theservice requirements with changing system capacity and allocation fairness in singlenon-real-time traffic model, an adjustable fairness algorithm is developed. By introducing anadjustable fairness factor, the proposed algorithm can decide appropriate scheduling criterionaccording to the transmission state and service requirement for each allocation, so as tocontributing an adjustable tradeoff between the system capacity and allocation fairness.Furthermore, in order to solve the resource competition problem in multi non-real-time trafficenvironment, a max capacity demand utility algorithm and its improved algorithm areinvestigated. By establishing the utility-pricing framework which concerning both channelquality condition and traffic transmission demand, the proposed algorithms can achieve anattractive tradeoff between system rate-sum capacity and the user capacity demands, therebyefficiently improving the processing capability for multi-service requirements. Secondly, the real-time traffic oriented DSA problem for the SC-FDMA system isanalyzed. In order to avoid the data loss in single real-time traffic model with finite queuingspace assumption, an improved max delay utility algorithm is proposed. By introducing thequeue length information based on the traditional max delay utility algorithm, the proposedalgorithm can effectively eliminate the system data loss due to the buffer overflow.Meanwhile, a max exponential utility algorithm is developed for further signaling overheadreduction. By exploiting the exponential utility function with respect to user average delay,the proposed algorithm can broaden the priority variation between users, and fully guaranteethe allocation superiority of the user suffering from long waiting time and queue length. So asto reducing the computational complexity while keeping good data loss and delayperformance. Moreover, in order to solve the resource competition problem in multi real-timetraffic environment, the QoS differentiation performance of the max exponential utilityalgorithm is discussed when providing traffic priority division with appropriate schedulingweights setup among different services. Under this consideration, a max graded exponentialutility algorithm is presented by taking the concept of grading theory. By means of setting twokinds of traffic scheduling weights, the proposed algorithm can provide more accessopportunities for the users with poor delay performance and low scheduling weights, therebyimproving the QoS provision capability for multi real-time traffic.Finally, the mixed traffic oriented DSA problem for the SC-FDMA system is analyzed.In order to overcome the service rate waste caused by assigning more data rate than user’stransmission demand, a max graded exponential utility algorithm with strict service rateconstraint is proposed. By integrating the concept of load control, the proposed algorithm canstrictly restrict the data transmission rate assigned to each user, and completely eliminate theservice rate waste. Meanwhile, for solving the unjust competition in service rate controlmechanism, a max graded exponential utility algorithm with adaptive service rate constraint isdeveloped. By means of setting the access threshold which is aware of both user transmissionstate and service requirements, the proposed algorithm can provide a strict and adaptivescheduling priority division between real-time and non-teal-time traffics, and achieve areasonable frequency resources distribution among mixed traffic users.