Patent ID: 7885244

Claim:
A method for communicating in a network including a coordinator node and a set of leaf nodes, comprising: transmitting periodically, from the coordinator node to the set of leaf nodes a beacon defining a superframe, wherein the superframe includes an active period and an inactive period following the active period, and wherein the active period includes a first contention access period (CAP- 1 ), a first contention free period (CFP- 1 ) following the CAP- 1 , a first group acknowledgement (GACK- 1 ) following the CFP- 1 , a second CFP- 2 following the GACK- 1 , a second GACK- 2 following the CFP- 2 , and a second CAP- 2 following the GACK- 2 , and wherein each CFP includes a guaranteed time slot (GTS) assigned to each leaf node; transmitting, by each leaf node to the coordinator node, only during the GTS assigned to the leaf node during each CFP; partitioning the inactive interval of the superframe into inactive time slots, wherein each inactive time slot includes a main interval and a guard interval; wherein for transmission during the CFP- 1 , the first group acknowledgement message is transmitted at the end of the CFP- 1 ; wherein all acknowledgements are sent simultaneously as group, wherein the GACK is able to serve as an auxiliary beacon for subsequent retransmission; if a retransmission of data fails during the CFP- 1 , the data are retransmitted during the second CFP- 2 using different frequency which is indicated by the GACK; and wherein the superframe active interval comprises multiples of comprehensive CFP intervals.