Token-DCF, COMSNET(2013) -> MOBICOM(2014)
Introduction ▣ To improve standard MAC protocol of IEEE for WLAN. ▣ S-MAC, A-MAC, SPEED-MAC, and etc are for WSN. Close to Energy Consumption is the main issue. Duty Cycling ▣ Whereas, Throughput & Latency is of most important factor for WLAN.
Motivation ▣ a, b(1999), g(2003), n(2009), ac,ad(2013) Basic CSMA/CA being improved ▣ Problems of CSMA/CA unnecessarily long idle time –channel access delay, low channel utilization High collision rate –Still possibe to collide even with big CW size ▣ The paper is for reducing idle time and collision rate to get better throughput and latency.
Related Works ▣ Many researches for improving CSMA/CD Optimal CW size –Set optimal CW size immediately considering network status –optimal backoff distribution e,n –Transmit Opportunity (TXOP) – multiple frames –Reverse Direction (RD) – burst response
Related Works (cont.) ▣ Wireless Token Passing Protocols Token Passing is a medium access method where a short packet called token is passed between stations to authorize a station for transmission. To send data frame, it needs to possess token. No collision. ▣ Issues connectivity loss, network partitioning, token loss & duplication, network connectivity change. Round Robin Passing
Main Idea not round robin scheduling. Privilege (Token) Scheduling with neighbor nodes’ queue length >0. 2. implicit scheduling. Queue length information of source and token are collected by each neighbor node by overhearing through MAC header. Node with same Id can transmit next.
ad hoc mode / infrastructure mode
Evaluation Compared to g in NS-2 Wireless adhoc/infra network RTS/CTS turned off Each simulation – 30 seconds/10seconds. Averaged over 20 runs. Packet payload size – 1500 B P
Results – ad hoc
Results - infra
Ad hoc – detailed
Ad hoc – detailed (cont.)