Heterogeneous Wireless Access in Large Mesh Networks

Haiping Liu, Xin Liu, Chen-Nee Chuah, Prasant Mohapatra

University of California, Davis

IEEE MASS 2008

Outline

Introduction Related Work Theoretical Study Proposed Method Evaluation Conclusion

Introduction

The Major obstacles of large Wi-Fi mesh network Multihop transmission

The performance of multihop transmission decreases quickly as the number of hops increases

Link quality Depending on specific topologies and failure probabilities, the

proportion of island nodes may not be negligible. Distributed

In large mesh networks, centralized MAC-layer schemes, global link transmission scheduling, or synchronization are not practical.

Introduction

The Major obstacles of large WiMAX mesh network Spatial-reuse

Although the large cover age of WiMAX reduces the number of wireless hops in the network, it cannot support good spatial-reuse of spectrum.

Expensive WiMAX devices have much higher power consumption and are much m

ore expensive than Wi-Fi devices.

Deployment Wi-Fi devices have been widely deployed, and there fore it is beneficial

to integrate WiMAX networks with existing Wi-Fi network.

Architecture

Customer terminal

mesh node

WiMAX base station(WMBS)

portal

Related Work

WiMAX-only mesh network Cannot fully reuse bandwidth and disregards the widel

y deployed Wi-Fi device

Wi-Fi/WiMAX Few of them analyze the major drawbacks of Wi-Fi or

WiMAX-only mesh networks, offer theoretical proof of the heterogeneous architecture and publish corresponding solution.

Goal

The paper propose an integrated Wi-Fi / WiMAX architecture that exploits the advantages of both technologies.

The primary objective of this paper is to facilitate a good cooperation of the last two kinds of connections and improve the overall system performance

Theoretical Study – Notation

γ Maximum utilization in the heterogeneous network

Theoretical Study – Formulation

Theoretical Study – Environment Set

Environment Set

Node equips with both Wi-Fi and WiMAX devices

Link CapacityWi-Fi 54Mbps

WiMAX 70Mbps

CoverageWi-Fi between any two neighboring Wi-Fi nodes

WiMAX whole network

Theoretical Study – Solution and Analysis

Protocol Design

Although it is shown that a heterogeneous network is a good solution through the theoretical study, it is necessary to design a protocol that can achieve the gain in practice and deal with challenges that are not captured by the idealized model.

We propose a threshold-based protocol and an optimization algorithm

Assumptions

WiMAX utilized the scheduled MAC scheme.

In Wi-Fi networks, nodes utilize IEEE 802.11 MAC instead of the scheduled MAC as in theoretical study.

The WMBSs do not try to control the routing or scheduling inside the Wi-Fi network.

Proposed Protocol – LABHW

TH = 10

Conga = 5 < 10 = TH

WMBSNode a

Conga = 15 > 10 = THRequest

Collect Requests from all nodes and run the algorithm.

Reject Accept/

Traffic = 15

Receive and forward TrafficReclaim BWUpdate and Broadcast TH

LABHW Algorithm – Notification

LABHW Algorithm – Formulation

WMBS

Node i Node j

Evaluation – Environment Set

Environment Set

node equip with both Wi-Fi and WiMAX devices

link capacityWi-Fi 54Mbps

WiMAX 70Mbps

coverageWi-Fi between any two neighboring Wi-Fi nodes

WiMAX whole network

Simulator Qualnet 4.0

Evaluation

Evaluation

Evaluation

Evaluation

Evaluation

Conclusion

This paper proposes a heterogeneous network architecture, consisting of Wi-Fi and WiMAX.

To solve the major problems and improve the performance of multihop Wi-Fi mesh networks of large size.

Based on the insights from the theoretical study, we design a practical protocol.

Thank You