Simulation of VoIP traffic in n networks Aya Mire Niv Tokman Oren Gur-Arie

Contents n Packet aggregation Project goals Project assumptions Implementation Simulation flow Milestones

802.11n Based on IEEE – Standard for wireless computer networks Providing ability of working in a rate of at least 100Mbps. Support work with MIMO – several transmitters and receivers for each station Reverse direction communication Packet Aggregation Still under development - TGn

Packet aggregation Reduces the overhead of control packets and timeouts related to the protocol May be destined to single or multiple receivers

Project goals Examine the influence of aggregated communication on periodic information – with focus on VoIP Examine the influence of aggregation size (number of packets per aggregation) on network’s behavior

Project assumptions Centralized network environment (star topology) VoIP data only (of two types: 10ms, 60 bytes and 20ms, 80 bytes) Aggregation is done only by AP No ACKs

Implementation Network STA Simulation manager Statistics manager Conversation Generator STA AP

Simulation manager Handles the main loop of the simulation – the time counter (in step of 1us) Gathers the statistics from the different units of the system Manages the conversation generators

Regular station (STA) Represents a wireless client. Each STA contains Tx and Rx FIFOs for both sending and receiving messages. Data traffic between STAs goes through the AP. STA generate and handles the different control messages defined by n protocol

AP Similar implementation and behavior to STA. Buffers data from different STA until aggregation threshold is reached, or time limit has expired.

Network unit Simulates the traffic “on the air” Serves as a “pipe” between STAs and AP (and vise-versa) Inserts error into transmitted messages Detects collisions of packets (and flags them as erroneous)

VoIP data generators Generate VoIP data packets and inserts them to the STA’s Tx FIFOs Generation of data is periodic every 10ms or 20ms, and done simultaneously to two STAs engaging in conversations Several VoIP generators can work in parallel

Statistic for each VoIP type: Total number of messages during simulation time. Number of messages successfully sent. Average time of message transmission (from source to destination, via AP). Average waiting time in AP buffer. Average time from entering Tx FIFO to actual transmission time. Statistics without explicit reference to VoIP type: Number of aggregations less than max aggregation size. Average number of receivers in aggregation Number of collisions. Number of control messages.

Simulation flow 1. Data arrives at Tx FIFO of STA A from VoIP data generator. IAC is sent. 2. AP receives IAC, wait SIFS and respond with RAC. 3. RAC received. STA A sends non-aggregated VoIP data 4. After DIFS, the operation is repeated by STA B 5. Aggregation size is reached. AP send IAC followed by the aggregated data 6. Data is received by STA C

Project time table Week 1-2: Headers + Classes (data and methods), Statistics unit Week 3-5: STA, AP and Network unit Week 6: Simulation manager, data generators Week 7: Integration and testing, analyze simulation’s results