Time bandwidth balance-based scheduling in Bluetooth scatternet

• Main Authors: Su, I. F., 蘇義峰
• Other Authors: Jong, T. L.
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/60378891102125832342

碩士 === 國立清華大學 === 電機工程學系 === 99 === In this thesis, investigation on the issues of time bandwidth balance scheduling of Bluetooth communication from a practical applications viewpoint is discussed. Some research papers have been reported in the past on the issue of Bluetooth scheduling. However, most of them are focused on the “fairness” and transmission throughput of utilizing the Bluetooth transmission bandwidth among devices, without considering the service quality in practical applications situations. In practical applications, different Bluetooth devices require different processing and response time and service quality. Since the transmission rate in Bluetooth is not high, it would be pointless to overemphasize in transmission throughput. Whereas the major benefits of Bluetooth are convenience and low power consumptions, which means the service quality of Bluetooth seems more important than the “fairness” and transmission throughput, especially in circumstances where there are more Bluetooth connections and devices requiring high QoS, For example, the QoS in audio quality should be more important than the throughput in file transfer. That’s because the human auditory systems can clearly distinguish the difference and quality of sounds. When the connections increase, assuming that the time bandwidth allocated for each connection is not big and even not enough for the audio connections, the fairness issue in scheduling becomes less important. What’s important is how to maintain the connection bandwidth of the audio device (A2DP connection) so that the audio quality is maintained. In this thesis, a time bandwidth balance-based scheduling is proposed to solve such problem. First, participant links with Link Priority greater than 0 are selected based on a simplified formula devised to compute the Link Priority. Second, candidate links are chosen from the participant links based on a frame time criterion. Finally, a bandwidth debt for each candidate link is computed using proposed formula and is used to decide the scheduling of each candidate link. Some experiments are performed and results show that the proposed scheduling method can effectively maintain the connection bandwidth and sound quality of A2DP connection under multiple FTP connections situations. Meanwhile, by adjusting the weight of bandwidth-debt of A2DP connection, the proposed time bandwidth balance-based scheduling can tolerate severe interference circumstances (measured by the number of retransmission) and maintain the sound quality of A2DP connection (provide 300 timeslots/s for A2DP) under up to extra 6 FTP connections.