In wireless networks, a channel can be allocated between source and destination, and in between source and destination each router is connected to its neighbour router in peer to peer manner, the whole channel consists of a number of routers.
So some of the channels are used for static routing and some of them are for dynamic routing schemes.
The different types of channel allocation schemes are as follows −
Now let us discuss dynamic channel allocation.
In this channel an interface can switch from one channel to another channel frequently. The dynamic strategies require frequent channel switching and therefore it has higher overheads than static strategies. The channel allocation can be changed with the changing traffic.
There are some key assumptions in Dynamic channel allocation, which are as follows −
Independent Traffic − This model consists of N independent stations with a program or user that generates frames for transmission. Once a frame has been generated the station is blocked and it does not do anything until the frame has been successfully transmitted.
Single channel − A single channel is available for all communication All stations can transmit on it and all can receive from it.
Observable collision − All stations can detect that a collision has occurred. A collided frame must be transmitted later.
Continuous or slotted time − Time may be assumed continuous; frame transmission can begin at any instant. In other way, time may be slotted or divided into discrete intervals. Frame transmission must then begin at the start of a slot.
Carrier sense or No carrier sense − With the carrier sense assumption, stations can tell if the channel is in use before trying to use it. Station will transmit only when the channel is free.
Let us consider cellular telephone in a city, users move and they can turn a cell phone on and off at any time. Therefore, the set of cell phones are operating in the range of a given cell tower that varies constantly.
In such a situation a dynamic channel allocation scheme is needed where a mapping can be established when a new station appears, and the mapping can be removed when the station disappears.