| LTE-Advanced wireless communication system has been widely concerned with its superior performance, the performance of the system cannot be separated from the fully support of the wireless spectrum resources, and it is not realistic to meet the need of 100MHz bandwidth for the LTE-Advanced system in the continuous frequency band because of the available radio resources become scarcer and scarcer with the rapid development of the wireless communication system. By using carrier aggregation technology and aggregating multiple carriers in different frequency bands, LTE-Advanced not only meet the needs of the huge bandwidth, the system also made significant breakthrough on the use of the spectrum resource. At the same time, we should also concern that because of adopting carrier aggregation technology, the user can be accessed by multiple carriers for data transmission, which also brings new problems for the system resource scheduling.Today’s research on LTE-Advanced system resource scheduling often ignored the scenario that LTE users coexist with LTE-A users and problems existing are as follows. First, the existing scheduling scheme didn’t consider the difference of equipment ability between above two systems and didn’t give a reasonable user access scheme in the scenario that LTE user coexist with LTE-A user. Second, the existing resource scheduling schemes existed serious unfairness to LTE users. Third, most research work failed to conduct a comprehensive research and improvement but focused on a particular aspect of the scheduling mechanism, carrier level-scheduling, and RB-level scheduling. This article made corresponding improvement on all of these aspects and fully considered the scenario that LTE users coexist with LTE-A users, and successfully promoted the fairness performance of LTE users in this scenario, the specific improvement scheme is as follows.(1) In terms of scheduling mechanism, this paper put forward an improved Half Separated User Scheduling mechanism, which presented different user access scheme according to equipment ability of different system users in the scenario that LTE users coexist with LTE-A users. Moreover, the scheduling mechanism in this paper considered the change of the channel quality, allowed the user to switch component carrier when the channel quality decreased to a certain degree, and presented carrier switching scheme. Simulation results showed that the proposed scheme can significantly improve the throughput performance of the system when the channel quality changes fiercely.(2) In terms of carrier-level scheduling, because of Least Load algorithm just considered the number of users or packet length when measure the load of each carrier, this paper redefined the measurable indicator of the load on the component carrier, and proposed an improved Least Load algorithm based on the residual transmission time. This algorithm inherited the main idea of Least Load algorithm and fully considered the channel quality factor of different carriers, regarded the remaining transfer time of the rest data in component carriers as the index of the load, which make the system better on load balancing performance.(3) In terms of resource block level scheduling, because of the unfairness of LTE users in Proportional Fair algorithm, this paper improved the Proportional Fair algorithm and proposed an improved Proportional Fair algorithm. The main idea of this algorithm is that properly enhancing the scheduling priority of LTE users when the percentage of LTE users is low, improved the LTE users’ performance in the scenario that LTE user coexist with LTE-A user, and promoted the fairness performance of the system.Finally, this paper analyzed and verified the advantages and disadvantages of the above three kinds of improved algorithm with MATLAB. The results of the simulation showed that above-listed three algorithms brought effective performance improvements in both throughput and fairness. |
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