A SURVEY OF GEOCAST ROUTING
PROTOCOLS
指導教授：許子衡 教授
學生：翁偉傑
1
IEEE Communications Surveys & Tutorials • Second Quarter 2007
OUTLINE

Abstract

Geocast routing protocols


Routing with flooding

Routing with directed flooding

Routing without flooding
Simulation Results
2
ABSTRACT



(1/2)
Geocasting is the delivery of a message to nodes
within a geographical region.
This paper is to compare the differences of
geocast routing protocols and discuss their
features.
Finally, simulation to compare the differences of
geocast routing protocols.
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ABSTRACT

(2/2)
Geocast taxonomy
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GEOCAST ROUTING PROTOCOLS


(1/11)
The geocast routing protocol would still be the
basic mechanism to deliver messages from a
sender to a geographic region.
對於大多數的方法，我們都假設每個節點可以透過
GPS知道自己的位置。
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GEOCAST ROUTING PROTOCOLS
(2/11)
Routing with Flooding

Simple Flooding

provided that this packet was not already received
before in order to avoid loops and endless flooding.

A node delivers a packet if the own location is within
the specified destination region

這是很穩定但是沒有效率的方法。

是許多geocast protocols的基礎。
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GEOCAST ROUTING PROTOCOLS
(3/11)
Routing with Directed Flooding

Location Based Multicast (LBM) 矩形
LBM Scheme 1:When a node
receives a geocast packet, it will
forward the packet to its neighbors
if it is within a forwarding zone;
otherwise, it will discard the packet.
Forwarding zone 大小：
-destination region
-sender location
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GEOCAST ROUTING PROTOCOLS
(4/11)
Routing with Directed Flooding

Location Based Multicast (LBM) 錐形
LBM Scheme 2: Unlike scheme 1,
scheme 2 does not have a
forwarding zone explicitly.
第二個方式是樹狀法，透過座
標計算出每個節點與目的地中
心的距離，傳送端透過距離比
自己近的節點來傳送封包。
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GEOCAST ROUTING PROTOCOLS
(5/11)
Routing with Directed Flooding

Voronoi Diagrams
A voronoi diagram partitions the
network in n voronoi regions.
改進了LBM，考慮到鄰居的位置，
所以可以避免forwarding zone是空
的。目的地不是由單一位置來定義，
而是由一個區域來決定。
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GEOCAST ROUTING PROTOCOLS
(6/11)
Routing with Directed Flooding

Mesh

After a node inside the destination region received
the initial packet to join the mesh, a unicast reply is
sent back to the sender on the reverse path and
flooding is stopped.

目的地的節點接收到初始的封包後會加入mesh，並順著
原本的路徑透過unicast回覆傳送端來停止flooding。

每個中繼節點需要記錄並維持狀態資訊。
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GEOCAST ROUTING PROTOCOLS
(7/11)
Routing with Directed Flooding

GeoGRID
方法一：
GRID的概念就是將網路分割成許
多格。
為了減少flooding的overhead，在
forwarding zone外收到的封包直接
丟棄。
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GEOCAST ROUTING PROTOCOLS
(8/11)
Routing with Directed Flooding

GeoGRID
方法二：
ticket-based Geo-GRID。
每個閘道最多只能傳送給3個鄰居，
會挑選3個離目的地較近的節點傳
送。
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GEOCAST ROUTING PROTOCOLS
(9/11)
Routing without Flooding

Unicast Routing with Area Delivery(URAD)

它是一個簡單的geocast路由協定，傳送端和目的地之間
使用unicast來傳播。


分為兩個階段：

從傳送端透過unicast傳到目的地內的第一個節點。

在目的地內進行flooding。
Unicast路徑上的每個節點都會檢查自己是不是在目的地
裡，如果是，則停止unicast並開始區域性的flooding。
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GEOCAST ROUTING PROTOCOLS
(10/11)
Routing without Flooding

GeoNode
定義了3種方法來整合地理位置：
-Unicast IP routing to deal with GPS
address.
-GPS-Multicast
-Application-layer solution using
extended DNS.
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GEOCAST ROUTING PROTOCOLS
(11/11)
Routing without Flooding

GeoTora
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SIMULATION RESULTS

(1/3)
模擬和比較的協定有：Simple Flooding、URAD、
矩形的LBM和圓錐形的LBM。

模擬環境

使用NS-2來模擬。

模擬被安裝250m無線傳輸範圍和由100到1000個節點組
成的IEEE 802.1網路。

節點跟著隨機的waypoint模型移動，速率最高50m/s。
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SIMULATION RESULTS
- Simple Flooding 有較大的網路負載，成功率高。
- LBM矩形和LBM錐形有較小的網路負載，成功率低。
(2/3)
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SIMULATION RESULTS
- 網路密度是一個平均每五個鄰居節點，網路區域是隨機節點數。
- LBM方法錐顯示了減少網絡負載。
- 較長的路由路徑，丟失率增加。
(3/3)
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