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Wireless Mesh Network: provides Network Communication through radios which require minimal configuration and infrastructure by arranging nodes in a Mesh Topology. A mesh network is reliable and offers redundancy. Wireless mesh networks often consist of mesh clients, mesh routers and gateways. When one of the nodes is not functional, the rest of the nodes can still communicate with each other, directly or through one or more in-between nodes. Wireless mesh networks can be implemented with a variety of wireless technologies which includes 802.11 and 802.16.
It has the characteristics of Self Forming and self Healing so there is no need for centralized management as the relation between mesh nodes fulfils this requirement.
These Wireless Networks have their own Strengths and Weaknesses and can be used at different phases of development and growth of the Network.
First Generation: Single-Radio gives connection to individual user devices and backhaul (links across the mesh to the wired or fiber connection), that creates wireless congestion at each node. In this type only two radio "hops" possible between connections to the wired or fiber Ethernet. Video and Voice applications performance is also very poor. Clients and the backhaul share same radio, there is RF interference issues too from other radios operation on the same frequencies.
Second Generation: Dual Radio: To Solve these WMN congestion problems the Dual Radio was developed by having two radios in each node. A combination of IEEE Standard 802.11 b/g Service Radio with an 802.11 a backhaul radio. With the Dual-Radio type it was a slight performance improvement but with heavy user demand the congestion problem with the backhaul link stayed there as the Dual-Radio doesn't have a dual- radio backhaul. The issue of RF Interference can only happens if a radio operating on unlicensed backhaul frequency and therefore the whole network need to switch channels, which is unrealistic in the actual practice.
Third Generation: Multi-Radio Mesh: works as unique pair of dedicated radio on each end of the link so unique frequency is being used for each wireless hop and therefore a dedicated (CSMA) Carrier Sense Multiple Access collision domain. This is the best Mesh link with maximum performance and no bandwidth degradation and without adding latency. Therefore quality performance can be achieved on Voice and video applications. In third generation type one of the mesh nodes dedicates one of the radios to act like a station and connect to the neighbour node Access Point radio. There are no RF interferences as each backhaul is split into two radios, which works on two different channels.
VoIP is one of the very important and useful applications used to make wireless local telephone calls through Wireless Mesh Network management support by using Quality of Service method. This type of infrastructure can be decentralized (with no central server) or even centralized (with a central main server); both methods are very reliable and resilient and economical. Nodes in this topology perform as routers and transmit data from nearby nodes to peers that are far to reach in one leap this makes the network to cover long distances. Mesh topology is very reliable as each node is connected to other if there is a hardware failure or any other reason makes the node disconnected from the network, neighbour nodes find the best route using advance routing protocols. The concept is like wired internet in which the packets travel around, the data hop from one device to another until it reaches the destination. Dynamic routing method is applied in each device to communicate routing information to other device. Now each device finds out what to do with the data it received either pass it to next device or keep it, according to the protocol. These routing protocols applied ensure the best (fastest) route to the destination.
Backhaul:( portion of the network comprises the intermediate links between the core network, or backbone, of the network and the small subnetworks at the "edge" of the entire hierarchical network.
For example: Connecting wireless base stations to the corresponding base station controllers.)
A collision domain is a physical network segment where data packets can "collide" with one another for being sent on a shared medium, in particular in the Ethernet networking protocol. A network collision is a scenario wherein one particular device sends a packet on a network segment, forcing every other device on that same segment to pay attention to it. Meanwhile, another device does the same, and the two competing packets are discarded and re-sent one at a time. This becomes a source of inefficiency in the network. Carrier Sense Multiple Access (CSMA) is a probabilistic Media Access Control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus, or a band of the electromagnetic spectrum.
Main elements influencing the design of a routing protocol for WMNs
Is there an IEEE standard that covers the topic researched?
One of the main reasons for having too many protocols is Lack of Standard set by IEEE for WMNs, which defines its operations. IEEE 802.11s started as a Study Group in September 2003 then became a Task Group in July 2004 since then many joint proposals have been submitted which were accepted and formed a shape of Draft. The final Draft was approved by Working Group (WG) in March 2009 but IEEE 802.11s is still under development. addendum
IEEE Standards Association: The Patents Owners IEEE 802.11s:
Apple Computer, Inc. 11-Oct-2005
Trapeze Network, Inc. 16-Nov-2005
Intel Corporation 22-Dec-2005
Cisco Systems, Inc. 12-Jul-2007
Symbol Technologies, Inc. 24-Jul-2006
Huawei Technologies Co., Ltd. 20-Jun-2007
Microsoft Corporation 20-Jun-2007
Qualcomm Incorporated 7-Jul-2007
Research in Motion Limited 17-Jul-2007
Fujitsu Limited 10-Sep-2007
Toshiba Corporation 29-Oct-2007
InterDigital Technology Corporation 8-Feb-2008
INRIA (Institut National de Recherche en Informatique et en Automatique) 25-Feb-2008
NTT DoCoMo, Inc. 5-Mar-2008
Thomson S.A., Thomson, Inc. 14-Jul-2008
LG Electronics Inc. 24-Dec-2008
Koninklijke Philips Electronics N.V 15-Jan-2010
IEEE 802.11s extends the IEEE 802.11 MAC Standard with the protocol that support Broadcast Multicast and Unicast delivery using radio aware over self-configuring multi-hop topologies.
Unlike existing Mesh Devices, 802.11s makes a transparent 802 broadcast domain that supports any higher layer protocol and provides frame forwarding and path selection at Data Link Layer (layer -2)
Motorola WMN Devices
IAP 4300 - Intelligent Access Point
The intelligent access point acts as a bridge between the wired world and the wireless mesh network.
The IAP 4300 is available either in a single radio configuration with a 2.4 GHz WiFi radio (802.11 b/g) or in a two radio configuration with an additional 5.8, 5.4 or 4.9 GHz (802.11a) radio.
Mesh Wide Area Network AP 7181
The AP 7181 is a high-performance, multi-radio 802.11n access point featuring superb network capacity, a maximum data rate of 300 Mbps and Motorola's unique intelligent ADEPT (ADvanced Element Panel Technology) antenna system.
With the exclusive, ADEPT (ADvanced Element Panel Technology) antenna system, the AP 7181 achieves maximum data rates of up to 300 Mbps by delivering a reliable dual data stream in an outdoor environment. Leveraging multiple transmit and receive RF chains and dual polarized antennas, the AP 7181 achieves superior mesh throughput throughout a coverage area.
The AP 7181 is the result of years of customer research and development and is designed specifically to meet the outdoor network needs of municipal agencies, transit systems, and enterprises.
IAP 6300 - Intelligent Access Point
In a MOTOMESHTM Solo network, the Intelligent Access Point (IAP) is a small, low-cost device that serves as a transition (change-over) point from the wireless network to the wired world or provides the functions of an enhanced wireless router by providing wireless network access to one or more IP devices via built-in Ethernet. Each IAP offers a maximum burst rate of up to 6 Mbps that can be used for voice, video and data communications.
If greater network capacity is required, additional IAPs can be easily deployed - without the need for extensive RF or site planning. The location of IAPs is non-critical due to the self-forming, self-healing and self-balancing nature of the MOTOMESH Solo network.
IAP 7300 - Intelligent Access Point
The Intelligent Access Point (IAP) provides the wireless gateway between a MOTOMESHTM Quattro network and the wired world. If greater network capacity is required, additional IAPs can be easily deployed.
The IAP7300 contains two standards-compliant, 802.11 (WiFi) radios and two of Motorola's widely acclaimed Mobility Enabled Access (MEA) mobile broadband radios. One set of WiFi and MEA radios operate in the unlicensed, 2.4 GHz band and the other set operate in the licensed, 4.9 GHz public safety band.
VMM 4300 - Vehicle Mounted Modem for Mobile Wireless Connectivity
The VMM 4300 enables any vehicle, train or bus to offer secure and reliable wireless broadband connectivity at highway speeds.
With Motorola's Mesh Wide Area Networks (MWAN) technology users can access critical broadband applications virtually anytime and anywhere. The VMM 4300 supports broadband data rates while in motion.
Mesh Wireless Video Camera
Motorola's mesh and Wi-Fi enabled camera video system is a robust, low-cost, easy-to-deploy, wireless solution for fixed and mobile video. Integrating Motorola's Mobility Enabled Access (MEA) technology or Wi-Fi directly into Sony's IPELA®camera has created a solution that is smaller and more cost-effective than conventional wireless video systems. Utilizing either licensed 4.9 GHz or unlicensed 2.4 GHz frequencies, the Mesh Wireless Video Camera system can be part of a larger Mesh Wide Area Network (MWAN), or act as a standalone video solution. Users can wirelessly access high-quality video feeds - even while travelling at highway speeds.
Microsoft Researching to create wireless Technologies which can connect neighbourhood Networks together
There are many advantages to enabling such connectivity and forming a community mesh network. For example, when enough neighbors cooperate and forward each others packets, they do not need to individually install an Internet "tap" (gateway) but instead can share faster, cost-effective Internet access via gateways that are distributed in their neighborhood. Packets dynamically find a route, hopping from one neighbor's node to another to reach the Internet through one of these gateways. Another advantage is that neighbors can cooperatively deploy backup technology and never have to worry about losing information due to a tragic disk failure. A third advantage is that this technology allows bits created locally to be used locally without having to go through a service provider and the Internet. Neighborhood community networks allow faster and easier dissemination of cached information that is relevant to the local community.
Community-based multi-hop wireless networks is disruptive to the current broadband Internet access paradigm, which relies on cable and DSL being deployed in individual homes. It is important because it allows free flow of information without any moderation or selective rate control. Compared to the large DSL and cable modem systems that are centrally managed, mesh networking is organic - everyone in the neighborhood contributes network resources and cooperates.
However, to realize the community-based goal, one has to solve many challenging problems including; capacity and range enhancement, privacy and security, self-stablizing and multi-path multi-hop routing, auto-configuration, bandwidth fairness, etc. In addition to solving the tough problems, success also depends on spectrum etiquette, business models, and economics. We are investigating some of the fundamental technical problems that continue to remain challenging despite several decades of research in packet radio networks. We have deployed testbed networks in our office buildings and in a local apartment complex.