To enhance spectrum efficiency in next generation heterogeneous wireless systems, it is important to improve shared spectrum usage between unlicensed long-term evolution (LTE) systems, such as the license assisted access (LAA), and legacy systems, such as wireless local area networks (WLANs), and carefully evaluate their performance. The LTE-LAA uses listen before talk (LBT) schemes to enhance the coexistence performance. However, available LAA-LBT schemes may incur several problems, such as a slot jamming effect and a significant slot boundary tracking error, leading to degraded performance. In this paper, we develop an LBT scheme with improved design and software defined radio (SDR)-based experimental procedure for performance validation. We program the improved LBT algorithm in SDR FPGA, and compare the results with original LBT algorithm. This work also develops an automated testing technique and new SDR functions that allow to modify the LAA parameters in realtime (such as backoff idle slot durations). The experiment result confirms the predicted slot-jamming effect, and shows that that our improved design enhances the LAA throughput. These results provide not only more robust LAA-LBT design, but also a new method on SDR programming and testing, and insight into the coexistence performance of heterogeneous systems.
Proceedings Title: 2017 IEEE Globecom
Conference Dates: December 4-8, 2017
Conference Location: Singapore, -1
Pub Type: Conferences
Coexistence, FPGA programming, LTE-LAA, SDR experiments, Test Automation, WLAN.