Table 1 Notation

N(u)

Set of neighbor nodes of node u

a(u)

Active slot of node u

τ

The number of time slots in a working period

L _i

Set of nodes in layer i

T _CDS

Connected dominating set tree

CD

Set of candidate dominators

DS

Set of dominators

P(u,v)

The shortest path in terms of delay from nodes u to v

d(u,v)

Delay from nodes u to v

d2d(u)

The smallest delay from node u to upper dominator within 2-hop

p(u)

Parent of node u in T _CDS

Ox(u)

Set of overhearing working periods of node u

\(\overline {Tx}(u)\)

Set of forbidden transmission working periods of node u to avoid collision

rx(u)

The last receiving working period of node u

tx(u)

Schedule for transmission of node u