Patent ID: 8588124

Claim:
A method for data communication in a radio network, the method comprising: calculating an expected value of transmission efficiency of a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol and an expected value of transmission efficiency of a Slotted ALOHA protocol; switching a mode into the mode of the protocol having the larger expected value from among the expected value of transmission efficiency of the CSMA/CA protocol and the expected value of transmission efficiency of Slotted ALOHA protocol; broadcasting, to stations (STAs), a message for indicating the STAs to switch a protocol into the protocol having the larger expected value of transmission efficiency; and transmitting data by using the protocol having the larger expected value of transmission efficiency, wherein the expected value S CSMA of transmission efficiency of the CSMA/CA protocol and the expected value S ALOHA of transmission efficiency of the Slotted ALOHA protocol are determined by the following equations: S CSMA = 2 ⁢ τ ⁡ ( 1 - τ ) k ⁢ a · L ( 1 - τ ) k + 1 ⁢ δ + ( k + 1 ) ⁢ τ ⁡ ( 1 - τ ) k ⁢ T s + { 1 - ( 1 - τ ) k ⁢ ( 1 - τ ⁢ ⁢ k - 2 ⁢ τ ) } ⁢ T c S ALOHA = 2 ⁢ a 2 ⁢ Lp c ⁡ ( 1 - p * ) k Where p * = a + ka - ( a 2 - 2 ⁢ ka + k 2 ⁢ a 2 + 2 ⁢ ak 2 ) 1 / 2 k ⁡ ( 2 ⁢ a - k ) , ⁢ p c = kp * 2 ⁢ ( 1 - p * ) ⁢ a + kp * , where τ is a transmission probability which is determined by the size of a congestion window of the CSMA/CA protocol and the number of retransmission stages, k is the number of STAs constituting a peer to peer (P2P) session, L is a traffic volume per unit frequency, δ is the time required for dropping without accessing a channel in a CSMA system, T s is the time required for completing transmission, T c is the time required for dropping when collision occurs and is given by characteristics of the CSMA/CA protocol, θ as a = exp ⁡ ( - θ ⁢ ⁢ N 0 P 0 ⁢ d 0 - α ) is a minimum signal to interference noise ratio (SINR) for demodulating a received signal, N 0 is a magnitude of noise, P 0 is transmission power, d 0 is a distance between an STA and an access point (AP), and α is a signal attenuation rate over a distance.