标题: | 在干扰环境下具适应性的蓝芽封包选择及排程策略 An Adaptive Bluetooth Packet Selection and Scheduling Scheme in Interference Environments |
作者: | 施辰翰 Chen-Han Shih 王国祯 Kuochen Wang 资讯科学与工程研究所 |
关键字: | 蓝芽;适应性封包选择方案;根据频道状况排程;Bluetooth;adaptive packet selection;channel state depedent packet scheduling;interference environment |
公开日期: | 2001 |
摘要: | 蓝芽是一个应用于无线个人区域网路的技术。它旨在消除各种装置之间装设电缆和连接器的需求。它可应用在个人电脑及其周边设备,随身听及其连接的耳机等。蓝芽提供具强韧性、安全性且支援数据和声音的无线电通讯,而这些装置不需要彼此都在视线之内。蓝芽使用2.4 GHz ISM 频带,与IEEE 802.11系列的无线区域网路共用同一频带。此两种网路本是互补而非互相竞争关系,然而它们互相干扰可能会不预期发生,此将严重降低彼此效能。在本论文中,我们提出根据频道状况进行蓝芽资料分割和重组的方案(CSD-SAR)及根据伫列状况作排程的策略(QSD-PR)。CSD-SAR 会建构一个接收频道表(receiving frequency table),并根据此表去预测频道状况及选择最适合的封包格式和封包大小来传输资料。透过这个方法,不仅可以在不延迟传输下,避用不好的频道,并且在易于发生错误的环境下有较好的链路使用率及较好的效能表现。此外,QSD-PR 也利用这个接收频道表去避免在不好的频道传送封包,且给予彼此之间有较多资料要传送的主从对 (master-slave pair) 较高的优先权,以避免时槽的浪费。常见的排程策略如轮询排程(RR),在分时双工(TDD)的存取控制通讯协定下,不能提供较好的效能,此造成时槽的浪费,也不能确保公平性。模拟结果显示,与RR比较,无论在无错误或易于发生错误的环境下,我们提出的封包选择及排程策略能达到较好的链路使用率及较高的效能。我们提出的方案因为避免使用其他网路所占用的频道,所以也能消除对其他共用同一频带的无线区域网路之干扰。 Bluetooth is a new technology for Wireless Personal Area Networks (WPANs). It intends to eliminate the need of wires and connectors between a variety of devices, like PCs and their peripherals, walkmans and their earphones, and etc. Bluetooth provides robust and secure wireless radio communication of both data and voice, even when the devices are not within line-of-sight. Bluetooth employs the 2.4 GHz ISM band, sharing the same band with the Wireless LAN (WLAN) implementing the IEEE 802.11 series standard. While WLANs and WPANs are complementary rather than competing technologies, the likelihood of mutual interference may occur unexpectedly, which may impact the performance of either severely. In this thesis, we propose a Bluetooth channel state dependent data segmentation and reassembly (CSD-SAR) scheme and a queue state dependent priority (QSD-PR) scheduling policy. The CSD-SAR maintains a receiving frequency table to predict channel conditions and selects the best packet type and packet size to transmit data. In this way, it not only masks bad frequencies without delaying transmission but also leads to the best performance with high link utilization in error-prone environments. In addition, the QSD-PR also uses the receiving frequency table to avoid bad frequencies and gives a selected master-slave pair, which has more queued data to send between each other, a higher priority to eliminate the wastage of slots. The conventional scheduling policy, Round Robin (RR), yields poor performance with the time division duplex (TDD) based MAC protocol and results in slot wastage and may not ensure fairness. Simulation results show that our proposed scheme achieves better link utilization and higher throughput with bounded delay compared to the RR scheme in error-free and error-prone environments. Our scheme can also eliminate interference to other wireless networks that share the same spectrum, such as WLANs, by avoiding selecting channels occupied by other networks. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT900394041 http://hdl.handle.net/11536/68566 |
显示于类别: | Thesis |
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