Strategies for Sensor Networks
Chulhan Lee, Sriram Vishwanath
High throughput : Common messages
enable cooperation in the cluster-head
Decode-and-forward in a cluster-head
Duplexing (TDD/FDD) is used.
Single antenna system
BC Correlated MAC
Combination of broadcast channel (BC)
and correlated multiple access channel
BC and correlated MAC
Capacity bound slope is Capacity bound slope is
less than 45°. greater than 45°.
Using better channel only Only using MISO channel
obtains sum capacity. obtains sum capacity.
Full cooperation No cooperation Limited Cooperation
Channel condition Channel condition General channel condition
Power policy Power policy is obtained from
Generalization: two antenna model
BC is hard problem since this is not degraded BC
Common message W0 is necessary to generalize.
: priorities of W0, W1, W2
W0 is not necessary.
Capacity is achieved by dirty paper coding (DPC).
Encoding order: from higher priority to lower priority
Sum-capacity occurs on the R0=0 plane.
only common information W0
Decoding order: higher priority decoding later.
The decoding order at correlated MAC is the
reverse of the encoding order at BC.
Sum-capacity occurs on R1=R2=0 line.
Sum-capacity is obtained at the intersection of BC and
correlated MAC capacity bound.
The farthest point from (0,0,0) in the intersection is the sum-
Cooperation within cluster provides MIMO-
like gains in throughput for the overall
Intersection of BC and correlated MAC
capacity region guides power distribution