how does the source node know that the other node is within its radio range or not ?

[mistusen]

in my project,We consider an ad hoc network composed of battery powered mobile nodes. Each of them has got a radio-range (generally uniform for all nodes in the network),which is an abstract electronic circle around a node within which message packets can be transmitted and received. So, if a pair of nodes want to communicate when they are not within the radio-range of one another, it becomes the responsibility of neighbor of the source and it’s neighbors and so on, hierarchically, to provide the required ubiquitous connectivity between source and destination as there is no fixed infrastructure in the network.

so for establishing such network,i've some questions to ask;-
1 )how does the source node know that the other node is within its radio range or not?how do i write this part of the code in java using thread if we consider each node as a thread and they can communicate by passing messages between them.

[Nepomuk]

I would say first of all, every node needs some kind of ID. That could be an integer or a String or an object from a new class you write or anything else, that would be able to identify it.

Then you'll have to somehow define, which nodes are in range. Maybe you have a 2D field and each node has a position (an x and a y coordinate maybe).

Also, I'd have some kind of class, that knows all of the positions and can therefore tell a node, which other nodes are in range. (So it simulates the radio signals.) However, no node has to know where any other node is except for in or out of range.

Alternatively, you can send a message with the current position of the node trying to make the connection to every node. If it's in range it will reply with its node ID.

If the one you're looking for is in range, great. If it isn't, you'll have to connect via other nodes.

Greetings,
Nepomuk

[mistusen]

thanks for the reply......the information is really helpful....nodes are moving in a random fashion.....so if i design a class " that knows all of the positions of the nodes" ,then how do i take care of the nodes when they are randomly moving......

[mistusen]

i am clueless about the fact:how to implement the nodes as threads.......in java or in c++ which will be the proper choice for writting the code?please reply......i'm waiting for your suggestion

[JosAH]

Suppose a node #i wants to know whether or not a node #j is in range. Node #i
transmits a broadcast packet (message) to which every node that receives this
message should respond with its on node number. Node #i either receives a
response from node #j in a certain time interval (nodes are in range) or it doesn't
(the nodes are probably not in range).

If you want to allow hops it gets a bit more complicated but a breadth first search
would basically do the trick.

kind regards,

Jos

[mistusen]

thanks for the reply............how this message passsing between nodes can be done?i just can't write the code in java......plz give me some hints about writing the code.....example code or something like that.......so that i can start........

[JosAH]

thanks for the reply............how this message passsing between nodes can be done?i just can't write the code in java......plz give me some hints about writing the code.....example code or something like that.......so that i can start........

You have to define a boolean inRange(Node i, Node j) function. If two nodes are
in range a node #i can deliver a message to node #j. A Message can be an
interface which is used as a shared resource between a producer (Node #i) and
a consumer (Node #j). This is where synchronization and wait/notify comes in.
Have a look at the Queue interface API documentation.

kind regards,

Jos