Performance Analysis and Evaluation of WiMedia UWB MAC protocols Masters Thesis Proposal Rukhsana Ruby University of Victoria

History of IPTV IP/TV – First Internet Video product, 1995 An IPTV over DSL broadband by Kingston Communications, 1999 IPTV service by AT&T, 2006 – 300 channels in 11 cities Nowadays Broadband connections are widespread  Served more than 200 million households, 2005  Will grow to 400 million by 2010

IPTV in-home distribution Ethernet solution – Rewiring is expensive and awkward No new-wires solution – availability and achievable performance is uncertain Wireless solution

4 Outline Existing WLAN/WPAN Technologies UWB Overview Summary of UWB Experimentation Methodology Performance Results Discussion of limitations of current work Future Research

5 Existing WLAN Technologies Support low data rate (11 to 54 Mbps)‏  b and a/g (Achieve less than 50% of actual data rate)‏ Work in 2.4 and 5 Ghz frequency band.  avg throughput of g 10 Mbps Contention – based MAC family supports maximum 55 Mbps data rate in very short range (10 metre)‏

6 UWB Overview UWB is a radio technology UWB is regarded as the best technology for the high-speed wireless PAN. Why?  High speed at short range oUp to 480Mb/s currently. Ultimately support the speed at Gbit/s. oIn the range of 10 meters.  Radio spectrum: 3.1 to 10.6 GHz (very large).  Low energy consumption level

7 UWB MAC Time is divided into super frames.  256 MAS (Each MAS is 256us)‏ Beacon Period (First 32 MAS)‏  Contract and Expand able Data Period  DRP and PCA (Like e)‏ Acknowledgement Policy  No, Block and Immediate Acknowledgement

Overview of EDCAF User traffic is differentiated  Minimum contention window size  Retry limit  Arbitration inter-frame space  TXOP limit Backoff counter is decremented ahead of slot time no matter slot is busy or idle User traffic is denoted by AC i {i = 1, 2, 3,4}

9 Discussion (UWB Experimentation)‏ Tradeoff between TxRate and Retry Limit Throughput, Latency tradeoff between clustered and scattered reservation. Fig. Goodput vs. TxRate and Retry Limit Fig. Throughput vs. Reservation Pattern

Renewal Reward Theorem Other station’s transmission Tagged station’s transmission

EDCAF Analysis Fig: Illustration of renewal cycle C CS Frame service time = (E[R] + E[B])*generic slot

EDCAF Analysis(Cont.)‏ Expected number of backoff slots Expected number of retransmissions Transmission probability Collision probability of AC2 station Collision probability of AC1 station

EDCAF Analysis(Cont.)‏ Generic slot calculation Frame service time for AC1 station

EDCA Analysis (Cont.)‏ Frame service time for low priority station are two parts  Number of generic slots in zone 2  Pre-backoff waiting period First part of frame service time for AC2 station Each pre-backoff waiting period length Total pre-backoff waiting period Frame service time for AC2 station

EDCAF Analysis (With DRP)‏ No. of DRP faced by AC1 station Frame service time for AC1 station Frame service time for AC2 station T Q is the summation of DATA tx time, ACK tx time, SIFS and guard time

Simulation Methodology Simulator – ns-2 Modified TKN implementation of e  physical layer to UWB  Incorporate super frame structure  Insert some hard drp in super frame

Simulation Scenario AC 2 station AC 1 station Base station Radius of circle: 20 metre Tx range: 250 metre Freespace propagation model Data rate: 480 Mbps MAC layer Packet size with all overhead: 1500 bytes Min contention window for AC 1 : 7 Min contention window for AC 2 : 15 Retry limit: 7 AIFS 1 : 2 slots AIFS 2 : 4 slots

Saturated Simulation and Analysis Results (Without and with DRP)‏ Fig. Frame service time without DRP Fig. Frame service time with DRP Beacon period: 1-32 DRP: ,

Unsaturated Analysis Pre-backoff waiting period per backoff segment for AC 2 Prob of no AC1 station transmits in zone 1 Collision Prob of AC 2 station Collision Prob of AC 1 station

Unsaturated Simulation and Analysis Results (Without DRP)‏ Fig. Frame service time without DRP Number of stations: 10 Offered Load: frames/slot

Discussion Difficult to get the exact pre-backoff waiting period for AC 2 station. Due to propagation delay perfect simulation result is not possible. Frame service time in the presence of DRP is also approximation.

Future Research Extend the model to allow heterogeneous traffic. Send video over UWB, find performance metrics and improvement scope. Distributed algorithm for DRP allocation

Thank You! Questions?