.FLYINGHEAD WIRELESS INFRASTRUCTURE
.TITLE Cost of retransmission for mobile ad-hoc networks
.AUTHOR Humayun Bakht
.SUMMARY Mobile ad-hoc networks have the potential to turn the dream of being connected at anytime into reality. Before our dreams come true, there are a few obstacles in the way. In this article, Contributing Editor Humayun Bakht takes a look at those obstacles and how to work around them.
.DEPT
Wireless networks are created when two or more devices communicate with each other through radio waves. In current wireless systems, there are different types of hardware components involved that are required to perform various network control functions.
The whole idea behind the formation of wireless systems was to achieve faster and broader network coverage at a reduced cost. That’s why we find most of the techniques to support various network operations are modified versions of techniques that were used to support conventional networks. As time passes, researchers have started to look into possible network structures which can aid networking operations in places where a supporting structure isn’t present or it’s too costly or time consuming to deploy one.
Mobile ad-hoc networks have widely been seen as a potential technology which can turn the dream of getting connected at any time into reality. These networks were first implemented for military use. Recent advancements have reached the consumer market, as you’re probably more familiar with Bluetooth, WiFi and hyper LAN.
The phrase ad-hoc originates from Latin, which means "for this or for this only". Unlike fixed wireless networks, mobile ad-hoc networks are the temporary networks which can be deployed anyplace and anytime without the need of a pre-existing infrastructure. That’s why we occasionally refer to these networks as infrastructure-less or multi-hop networks.
The focus of current research is to come up with different strategies which can make these networks able to support routine networks jobs. Examples of some of the areas awaiting suitable solutions include routing, bandwidth constraints, security, hidden terminal problems and low power devices.
One of the fundamental purposes of any network formation is to exchange information between two parties. Sadly, most of the existing Internet protocols were designed to establish routing or packets exchange in networks that operate in the presence of some supporting structure. Basically, in mobile ad-hoc networks, nodes have to rely on each other in order to forward data packets from one to the other node in the network.
There are several reasons why mobile nodes in ad-hoc networks would prefer not to cooperate. When nodes do cooperate they establish the necessary ad-hoc structure that can make multi-hop communication possible by allowing traffic flow from a node to reach those destinations that would either require a significant amount of transmission energy using single-hop communication or simply not be possible without routing the traffic through other nodes.
This means that nodes must be willing to forward traffic for other nodes, and in the process spend energy for no direct benefit. If a node only considers its own short-lived period, as they themselves operate on low power battery devices, then it may not choose to participate within the network. Thus the concept of introducing a measure which can force the participation of nodes for collaboration into the architecture of mobile networks is an important aspect to be seen.
The combination of nodes must be able to focus on the dynamics of the nature of ad-hoc networks and must also be able to take many similar factors into account. This fact leads us to the situation where various pricing mechanisms have found application in rate control in static networks. However, the difference in this situation is that nodes recover costs associated with energy losses and traffic loading at a particular time through the credit arising from pricing mechanisms. Moreover, determining energy efficient routes is also an important consideration in mobile ad-hoc networks and pricing mechanisms can provide a means of guiding a system of nodes to its optimal operating path.
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Despite numerous benefits and advantages which mobile ad-hoc networks offer the wireless industry and network users, mobile ad-hoc networks lack a suitable solution which can assist participating nodes in deciding when and how a node can help any other node without putting itself in a dangerous state. Where routing is itself a big challenge in this area, a better organization guideline can be a supporting initiative in inventing a power efficient routing mechanism for this type of networking.
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