CAMAC VS QOSOSA Bin Liu and Zhisheng Yan

CA-MAC VS QOSOSA Bin Liu and Zhisheng Yan Chang Wen Chen - Qo. S-Driven Scheduling Approach Using Optimal Slot Allocation for Wireless Body Area Networks 2012 healthcom - CA-MAC: A Hybrid Context-aware MAC 2011 healthcom

content • 1. Introduction • 2. CA-MAC: A Hybrid Context-aware MAC Protocol • 3. Qo. S-Driven Scheduling Approach Using Optimal • 4. comparison

Introduction - With time-varying channel caused by frequent body movement, transmitted data may also experience deep fading and packet loss. - To meet the complex transmission requirements in WBAN, ■ CA-MAC: A Hybrid Context-aware MAC Protocol ■ Qo. S-Driven Scheduling Approach Using Optimal Slot Allocation

CA-MAC: A Hybrid Context-aware MAC Protocol - CA-MAC protocol use a hybrid of contention based and TDMA-based approaches. - The context awareness built in CA-MAC is based on both channelaware and traffic-aware functions.

CA-MAC: A Hybrid Context-aware MAC Protocol - Schedule-based slots are dynamically reserved to sensor nodes based on traffic requirements. - The polling-based slots, which are usually inactive with no transmission, are assigned to specific sensor nodes when emergency traffic occurs.

Channel-aware Adjustment of Access Mechanisms - when a sensor node fails to transmit a packet caused by deep fading, random backoff mechanism in CSMA/CA shall postpone its retransmission. contention length index (CLI) - NCDP is defined as the number of consecutively dropped packets from one sensor node. - TDC represents the times of data collision among all sensor nodes. - Master node can determine the final contention length (FCL) of next frame based on the average CLI (ACLI) of senor nodes

Channel-aware Adjustment of Access Mechanisms The upper bound and lower bound is denoted by α* ACLIpre and β* ACLIpre respectively.

Traffic-aware Adjustment of Transmission Priority - the transmission bandwidth and sampling rate of sensors are dynamically configured to satisfy the changing traffic demand.

Traffic-aware Adjustment of Transmission Priority TDMA MAC (fixed at 7. 45%)

Qo. S-Driven Scheduling Approach Using Optimal Slot Allocation - Qo. S-driven scheduling approach using optimal slot allocation to overcome technical challenges resulting from energy consumption, time-varying traffic and channel variation in WBAN. - The channel utilization and energy efficiency is negatively impacted due to introduction of contention-based period. - Mitigating the impact of fading only by utilizing the nature of contention to timely spread the transmissions is inadequate.

System model Good : transmission success BAD : transmission fail When τ goes to infinity,

Threshold-based Adjustment of Transmission Order - Propose a threshold-based scheme to adjust the transmission order of nodes. - Formulate an optimization problem to find the optimal number of slots assigned to each node while minimizing the energy consumption of sensor nodes. A. Threshold-based Adjustment - Good state can have scheduling better than bad state

Threshold-based Adjustment of Transmission Order B. Optimization of The Number of Allocated Slots ni and Si are the number of allocated slots and the minimum data rate requirement of node i, respectively, and R is the transmission rate in WBAN radio.

comparision PLRreduc is denoted the reduction of packet loss rate over fixed TDMA approach.

comparision