Transcript i,j

A Multicast Mechanism
in WiMax Mesh Network
Jianfeng Chen, Wenhua Jiao, Pin Jiang, Qian Guo
Asia-Pacific Conference on Communications, 2006.
(APCC '06)
Mei-zhen chen
Outline





Introduction
Overview of WiMax Mesh Network
Architecture Framework for Multicast
Performance Evaluation
Conclusion
Introduction

The standard of IEEE 802.16 only defines the
multicast connection in PMP mode in one hop range.

The Connection ID (CID) used for the multicast
service is the same for all Subscribe Stations (SSs)
that participate in the multicast.

How to construct a multicast tree in mesh mode is
undefined in the standard.
Introduction (cont.)

A multicast tree construction mechanism is proposed
based on the unicast routing tree in WiMax mesh
network.

The broadcasting feature of omni-directional antenna
is used to improve the transmission efficiency.
Overview of WiMax Mesh Network
 Two

scheduling methods:
Centralized scheduling
• Mesh BS is responsible for collecting bandwidth request
from SSs and managing resources.

Distributed scheduling
• A processing of three-way handshake.
Overview of WiMax Mesh Network
-assumption of the physical layer

Only time division mode (TDD) is supported in Mesh
mode.
 The MAC layer is assumed to schedule data to time
division multiple access (TDMA).
 This paper only considers the single carrier channel
for both uplink and downlink traffic.
Overview of WiMax Mesh Network
–control messages
 In


centralized scheduling,
MSH-CSCF (Mesh centralized scheduling
Configuration) message carries the information of
channel configuration and routing tree information.
MSH-CSCH (Mesh centralized scheduling)
message carries the information of bandwidth
request and grant.
Overview of WiMax Mesh Network
–control messages (cont.)
BS
SSs
MSH-CSCF
(broadcast)
Forward to SSs
Routing tree
MSH-CSCH
Determine the amount of
granted resources for
each link
transmit resource request
(Request message)
MSH-CSCH
(Grant message)
propagate
along the route tree
The SSs determine its
actual uplink and downlink
transmission time for data
transmission
Architecture Framework for Multicast
-Multicast Architecture
Architecture Framework for Multicast
-Multicast Architecture (cont.)
 Application/IP layer


This layer utilizes the services of the routing layer
to satisfy the multicast requirements of
applications.
It consists of two modules:
• Data packet transmit/receive controller
• Multicast session initiator/terminator
Architecture Framework for Multicast
-Multicast Architecture (cont.)
 MAC


layer
The major module in this layer is tree construction
module.
The input information to make the decision come
from three modules:
• Multicast Information Handler
• Neighbor List Handler

MSH-NCFG (Mesh network Configuration) message
• Centralized Scheduling
Architecture Framework for Multicast
-Multicast Architecture (cont.)
 Frame


Structure layer
The main function of this layer is to encapsulate
frame packets according to the format.
The message will be placed in control sub-frame
and the uplink and downlink data will be arranged
in data sub-frame.
Architecture Framework for Multicast
-Tree Construction

Definitions of node:




Source node:start point of the multicast session.
Receiver node:one of end points of the multicast session.
Tree node:located in the multicast tree but not receiver
node.
Agent node:selected for broadcasting to its one-hop
neighbor in some specific frame.
Architecture Framework for Multicast
-Tree Construction (cont.)
Architecture Framework for Multicast
-Mathematical Model and algorithm

Let T = (V, E) denote the routing tree defined in the
MSH-CSCF message,
 where

The nodes V are access points.
• All nodes in V are labeled with an integer.
• the root node is labeled with 0. (Mesh BS)

The links E are bi-directional wireless links between
neighboring nodes.
• All links are also labeled with integer.

The routing tree T has L layers.
Architecture Framework for Multicast
-Mathematical Model and algorithm (cont.)

Let G= (M,P) denote the multicast routing tree,
 where
 M are the group member of multicast tree,
include BS, source node S, Tree node T
={ i, i V  (i is a Tree Node)}, Agent Nodes A
={ i, i V  (i is an Agent Node)} and Receiver
nodes R ={ i, i V  (i is a Receiver Node)}.
 The set P are links between neighboring multicast
tree nodes.
Architecture Framework for Multicast
-Mathematical Model and algorithm (cont.)

H(i) :hop count from node i to BS.
 D(i,j) :the hop count between node i and j.
 Fi={(j)| (j,i)E} :the neighboring father of node i.
 C(i) :all the children of node i.
 Ni= {(j)|D(i,j) =1  H(j)≥H(i)} :one-hop neighbor set of node i
with same or larger hop count than i.
 Multicast Exponent MEi = | O( j ) || j  ( Ni  R)  ( Ni  A) :for
each node to select candidates for agent nodes.
Architecture Framework for Multicast
-Mathematical Model and algorithm (cont.)
Architecture Framework for Multicast
-Mathematical Model and algorithm (cont.)
Architecture Framework for Multicast
-Mathematical Model and algorithm (cont.)
Performance Evaluation

It used the network to compare proposed multicast
scheme with traditional scheme.
 There are total 19 nodes in, the source node is node
14 and the nodes in blue are receiver nodes.
Performance Evaluation (cont.)

Following the algorithm of shortest path and
multicast tree construction
Layer 0
0
2
0
Layer 1
Layer 2
Layer 3
Layer 4
2
2
3
5
2
1
1
0
0
1
1
0
4
2
1
Performance Evaluation -frame-slot
Bandwidth efficiency:
9.4% v.s. 5.5%
Performance Evaluation
–the variation of latency
20-rounds’ simulation
Traffics: Poisson distribution
Proposed mechanism:
average Delay/maximal delay:
21.6 / 28 frame slots
traditional mechanism:
52%
average Delay/maximal delay:
44.5 / 92.4 frame slots
Performance Evaluation
–delay for random choice of source/receiver node
200-rounds’ simulation
Source node: randomly
Receiver node: randomly (10)
Traffics: Poisson distribution
30%
80%
Performance Evaluation
–the variation for multicast duration
Source node: randomly
Receiver node: randomly
Num of Receiver node:
4,7,10,13,16
65%
6%
Conclusion

The paper have presented a multicast mechanism in
IEEE802.16 based mesh network.
 The proposed model can save more than 50% of the
frame-slots in peak value.
 Simulation results can improve efficiency remarkably.