於晶片CC2530上進行CSMA/CA協定的效能評估

Performance Evaluation of CSMA/CA on CC2530

盧瑋(Wei Lu)

指導教授 ： 郭耀文

國立暨南國際大學/科技學院/電機工程學系/碩士(2015年)

https://doi.org/10.6837/NCNU.2015.00292

摘要

在無線網路普及的現代，封包傳送效率日趨重要，碰撞的發生與傳送效率極為相關。在無線網路避免碰撞的機制中，IEEE 802.11 DCF協定與IEEE 802.15.4 CSMA/CA協定是最廣為人知的。他們主要的不同一是監聽通道狀態的方式與次數。在DCF協定中，節點不斷的偵測通道狀態，對通道狀態可以立即性的處理；在IEEE 802.15.4 CSMA/CA協定下，節點只會在backoff結束後偵測通道一次，期間若通道已被佔用是無法得知的。此篇論文主要是於IEEE 802.15.4晶片上建構與實現基於DCF協定的軟體架構，與IEEE 802.15.4 CSMA/CA協定進行比較。實驗成果呈現出，由於IEEE 802.15.4 CSMA/CA沒有持續偵測通道，其傳送失敗率會隨網路變大而急遽上升。因此，IEEE802.11 DCF協定在封包遺失率與整體吞吐量上是優於IEEE 802.15.4 CSMA/CA協定。

關鍵字

無線網路 ； 載波偵聽多路存取機制 ； IEEE 802.11 ； IEEE 802.15.4

並列摘要

Wireless networks are widely popular in modern. The collision occurring is one of the reasons affecting the transmission efficiency. To mitigate the collision issue, the carrier sensing multiple access with collision avoidance (CSMA/CA) protocol is widely applied in wireless networks. IEEE 802.11 DCF protocol and IEEE 802.15.4 CSMA/CA protocol are the most well-known CSMA/CA based protocols. The primary difference between them is how carrier sensing is performed. Stations continuously sense the medium before transmissions in an IEEE 802.11 network, while stations in an IEEE 802.15.4 network only sense once after backoff operation. The thesis is mainly about software architecture design of the IEEE 802.11 DCF protocol on an IEEE 802.15.4 transceiver. Experiment results show that, without continuously sensing, the transmission failure probability of IEEE 802.15.4 CSMA/CA increases dramatically with the network size. Consequently, the IEEE 802.11 DCF protocol provides better performance in the packet loss probability and throughput than IEEE 802.15.4 CSMA/CA does.

並列關鍵字

Wireless network ； CSMA/CA ； IEEE 802.11 ； IEEE 802.15.4

參考文獻

[1] IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” IEEE Std 802.11- 2012

[2] IEEE Standard for Local and metropolitan area networks— Low-Rate Wireless Personal Area Networks (LR-WPANs)- 2011.

[3] CC253x System-on-Chip Solution for 2.4-GHz IEEE 802.15.4 and ZigBee® Applications- User’s Guide.

[4] Giuseppe Bianchi, “Performance Analysis of the IEEE 802.11 Distributed Coordinator Function,” IEEE Journal on Selected Area in Communications, vol.18, pp.535-547, 2000.

[5] C. Wang, W. Tang, “A Probability-based Algorithm to Adjust Contention Window in IEEE 802.11 DCF,” Communications, Circuits and Systems, 2004. ICCCAS 2004. 2004 International Conference, June 2004.