Min-Te Sun, Lifei Huang, Anish Arora, Ten-Hwang Lai

Presented byMd Tareq Adnan

CSE 6590 - High Performance Computer Networks 1

Outline

Existing Multicast MAC ProtocolsProblems with Existing Multicast MAC ProtocolsBatch Mode Multicast MAC protocol, BMMMLocation Aware Multicast MAC protocol, LAMMPerformance Evaluation based on Simulation

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IEEE 802.11 multicast/broadcast Protocol

IEEE 802.11 multicast/broadcast protocol is based CSMA/CA

Increased probability of lost frames due to interference or collisions

MAC-level recovery on multicast frame

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Solution to unreliable IEEE 802.11 multicast/broadcast protocol

Batch Mode Multicast MAC protocol, BMMM

Reduces the number of contention phases Reduces the time required for a multicast/broadcast

Location Aware Multicast MAC protocol, LAMM

Uses node Geo location Further improve upon BMMM.

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Overview on CSMA/CA

A node before transmit listens to the medium

Backoff timer Contention phase Hidden terminal problem Distributed Coordination Function (DCF) MAC protocol

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Existing Multicast MAC Protocols and Problems cont…

In IEEE 802.11 RTS/CTS / ACK is not used for broadcast/multicast

Protocol in [19] Introduce RTS/CTS handshake WAIT_FOR_CTS WAIT_FOR_DATA Problems

Collision of CTS frames Short inter-frame spacing (SIFS) Direct Sequence (DS) capture ability Contention window [0,w]

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Broadcast Support Multiple Access (BSMA)

Introduce NAK Frame WAIT_FOR_NAK Problem

Collision of NAK Frame

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Existing Multicast MAC Protocols and Problems cont…

Broadcast Medium Window (BMW)

Each broadcast is treated as multiple unicast requests Each node maintains three lists

NEIGHBOR SEND BUFFER RECEIVER BUFFER

Problems Requires at least n contention phases for each multicast Long time for multicast process lead to time out

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Existing Multicast MAC Protocols and Problems cont…

BMMM reduces multicast time compared with BMW

Reduces n contention phases into one

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BMMM Provides Simple Coordination

Prevent neighbors from passing contention phase

RTS frame tells to transmit CTS sequentially

RAK frame tells to transmit ACK sequentially

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Why use BMMM

Greatly reduces the number of contention phases

No modification on control frame format

Co-exist with IEEE 802.11 protocols

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Batch Mode Multicast MAC Protocol(BMMM)

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Location Aware Multicast MAC Protocol(LAMM)

GPS location information

A subset S’ of S will be a cover set if A(S)=A(S’).

1. Sender receives an ACK from every node in S’

Receiver guaranteed to receive data frame without collision

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Location Aware Multicast MAC Protocol(LAMM)

2. Minimum cover set of S can be computed in O(n^4/3) time

3. Every receiver is guaranteed to receive the data frame without collision if the transmission area of a node is completely covered by the transmission areas of a set of nodes

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Cover Angle

If two nodes are at the same location, cover angle is [0,360]

If two nodes are R away, cover angle is Ø

Transmission area of p, A(p) is completely covered by C

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Why use LAMM

LAMM protocol is refinement of the BMMM protocol

US FCC has requested all wireless service carriers to provide 911 calls

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Expected number of contentionphases before data sent

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Successful Delivery Rate

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Successful Delivery Rate

Average Number of ContentionPhases

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Average Message Completion Time

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A Pointer to Future Work

Focus was to resolve the hidden terminal problem for multicast

Has not addressed the exposed terminal problem

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Thank You

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