Hop-by-Hop Routing in Wireless Mesh Networks with Bandwidth Guarantees

ABSTRACT:
Wireless Mesh Network (WMN) has become an important edge network to provide Internet access to remote areas and wireless connections in a metropolitan scale. In this paper, we study the problem of identifying the maximum available bandwidth path, a fundamental issue in supporting quality-of-service in WMNs. Due to interference among links, bandwidth, a well-known bottleneck metric in wired networks, is neither concave nor additive in wireless networks. We propose a new path weight which captures the available path bandwidth information. We formally prove that our hop-by-hop routing protocol based on the new path weight satisfies the consistency and loop-freeness requirements. The consistency property guarantees that each node makes a proper packet forwarding decision, so that a data packet does traverse over the intended path. Our extensive simulation experiments also show that our proposed path weight outperforms existing path metrics in identifying high-throughput paths

EXISTING SYSTEM:

The path with the maximum available bandwidth is one of the fundamental issues for supporting QoS in the wireless mesh networks. The available path bandwidth is defined as the maximum additional rate a flow can push before saturating its path. Therefore, if the traffic rate of a new flow on a path is no greater than the available bandwidth of this path, accepting the new traffic will not violate the bandwidth Guaranteed of the existing flows. The extensive simulation experiments demonstrate that our routing protocol outperforms the existing routing protocols for finding the maximum available bandwidth paths. ETT metric adjusted based on the number of the interference links and the existing traffic load on the interference links. IRU is the ETT metric weighted with the number of the interference links, while CATT extends IRU by considering the effect of packet size and raw data rate on the links because of the use of multiple channels.


DISADVANTAGE OF EXISTING SYSTEM:
The traffic rate of a new flow on a path is no greater than the available bandwidth of this path, accepting the new traffic will not violate the bandwidth guaranteed. A source identifies a widest path to a destination; intermediate nodes on the widest path may not make a consistent packet forwarding decisions by using the traditional destination-based hop-by-hop packet forwarding mechanism. To avoid loops when routing tables change is an important but difficult problem, and is outside the scope. The problem of identifying the maximum available bandwidth Path from a source to a destination, which is also, called the Maximum Bandwidth Problem (MBP). MBP is a sub problem of the Bandwidth-Constrained Routing Problem (BCRP), the problem of identifying a path with at least a given amount of available bandwidth polynomial-time, because the problem is NP-complete in nature. Even though we can find the available bandwidth of a given path, it is not easy to identify a schedule that achieves that bandwidth since the scheduling.



PROPOSED SYSTEM:

A new path weight that captures the concept of available bandwidth. We give the mechanism to compare two paths based on the new path weight. the widest path, many researchers develop new path weights, and the path with the minimum/maximum weight is assumed to be the maximum available bandwidth path. The expected transmission count (ETX) metric.

The bandwidth requirement of a certain request. The protocol in  checks the local available bandwidth of each node  to determine whether it can satisfy the bandwidth requirement. Some works consider the TDMA-based MAC model and discuss how to assign the available time slots on each link for a new flow in order
to satisfy the bandwidth requirement. The isotonicity property of the proposed path weight allows us to develop a routing protocol that can identify the maximum bandwidth path from each node to each destination. In particular, it tells us whether a path is worthwhile to be advertised, meaning whether a path is a potential subpath of a widest path.


MODULES:
ü Path Selection
ü Isotonic Path Weight
ü Table Construction and Optimality
ü Packet Forwarding and Consistency
ü Route Update
MODULES DESCRIPTION:

Path Selection
We would like to develop a distance-vector based mechanism. In the traditional distance-vector mechanism, a node only has to advertise the information of its own best path to its neighbors. Each neighbor can then identify its own best path. In this module, we mentioned that if a node only advertises the widest path from its own perspective, its neighbors may not be able to find the widest path. To illustrate, consider the network where the number of each link is the available bandwidth on the link.

Isotonic Path Weight
In this module, we introduce our new isotonic path weight, also describes how we use the path weight to construct routing tables. The isotonicity property of a path weight is the necessary and sufficient condition for developing a routing protocol satisfying the optimality and consistency requirements. We first describe the definition of isotonicity also here in this module.

Table Construction and Optimality
The isotonicity property of the proposed path weight allows us to develop a routing protocol that can identify the maximum bandwidth path from each node to each destination. In particular, it tells us whether a path is worthwhile to be advertised, meaning whether a path is a potential subpath of a widest path. In our routing protocol, if a node finds a new nondominated path, it will advertise this path information to its neighbors. We call the packet carrying the path information the route packet

Packet Forwarding and Consistency

In a traditional hop-by-hop routing protocol, a packet carries the destination of the packet, and when a node receives a packet, it looks up the next hop by the destination only. In our mechanism, apart from the destination, a packet also carries a Routing Field which specifies the next four hops the packet should traverse. When a node receives this packet, it identifies the path based on the information in the Routing Field. It updates the Routing Field and sends it to the next hop.

Route Update

After the network accepts a new flow or releases an existing connection, the local available bandwidth of each node will change, and thus the widest path from a source to a destination may be different. When the change of the local available bandwidth of a node is larger than a threshold (say 10 percent), the node will advertise the new information to its neighbors. After receiving the new bandwidth information, the available bandwidth of a path to a destination may be changed. Although the node is static, the network state information changes very often. Therefore, our routing protocol applies the route update mechanism.


SYSTEM REQUIREMENTS:
HARDWARE REQUIREMENTS:

•         System                 : Pentium IV 2.4 GHz.
•         Hard Disk            : 40 GB.
•         Floppy Drive       : 1.44 Mb.
•         Monitor                : 15 VGA Colour.
•         Mouse                  : Logitech.
•         Ram                     : 512 Mb.

SOFTWARE REQUIREMENTS:

•         Operating system           : - Windows XP.
•         Coding Language :  JAVA

REFERENCE:
Ronghui Hou, Member, IEEE, King-Shan Lui, Senior Member, IEEE, Fred Baker, and Jiandong Li, Senior Member, IEEE, “Hop-by-Hop Routing in Wireless Mesh Networks with Bandwidth Guarantees”, IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. 11, NO. 2, FEBRUARY 2012.