22-08-2013, 04:48 PM
Capacity of Networks with Mobile Nodes
Networks with Mobile .pdf (Size: 162.89 KB / Downloads: 14)
How many transmission schemes are there?
• There are finitely many transmission schemes:
– Each node is either transmitting or staying quiet (finite combinations).
– Each transmitter is transmitting data of one out of n nodes (finite
possibilities).
– Each transmitter is transmitting to one out of n nodes (finite
possibilities).
• The precise number of transmission schemes depends on capabilities of
nodes:
Can nodes forward other nodes’ packets?
Is spatial reuse allowed?
Is power control allowed?
etc.
Specifying the Basic Rate Matrices
• So far: capacity region is convex hull of basic rate matrices.
• Still need to specify them!
• Each network has a repertoire of basic rate matrices depending on:
Multiple hops allowed?
Multiple transmissions allowed?
Power Control?
Successive Interference Cancellation?
• More capabilities ⇒ more basic rate matrices ⇒ larger capacity region.
Successive Interference Cancellation (SIC)
• Without SIC, each node treats signals intended for other users as noise.
• With SIC, nodes may decode interference signals and subtract them out.
– Advantage: Subtracting interference increases the data rate that the
receiver can handle.
– Disadvantage: SIC imposes a constraint on the rate of the interfering
link.
– Disclaimer: The decoded interfering signal is not forwarded.