The authors focuse on the star topology of 802.15.4 expected to be a dominant type at least the foreseeable future. Each device uses a slotted CSMA/CA. The authors propose a new analytic model of the IEEE 802.15.4 slotted CSMA/CA, which throughput and energy consumption are computed in saturation condition. The proposed model utilises the probability of device in the channel sensing states instead of the channel accessing states.
Markov Chain Model of IEEE 802.15.4 slotted CSMA/CA proposed
- Propose Markov Chain Model for 802.15.4
- Analyse the throughput and energy consumption in saturation condition
- The proposed model utilises the probability of a device in the channel sensing states instead of the channel accessing states
stochastic backoff counter, stochastic backoff stage, maximum stage, Wi, first CCA and second CCA slots, The busy probability of the channel at the first CCA and at the second CCA, transition probabilities, conditional probabilitiy that a device is at one of the first CCA states, The probability that the given device transmits a packet successfully after performing CCA twice, the saturation throughput, the payload length in the number of slots, the number of occupied slots for successful transmission and collision, time duration to perform CCA, time for transmitting an L-slot packet, time for waiting ACK, time for receiving ACK, The average number of backoff slots a device experiences to transmit a packet successfully, the average number of busy slot due to packet transmissions of other devices out of the backoff slots, the probability that the given device does not perform the first CCA and others perform the first CCA, the probability that the transmission is successful, average number of backoff slots during the successful transmission, average number of backpff slots during the collision of others, average number of the first CCA attempts for the given device to transmit a packet successfully when all devices are in the backoff states, the case of performing the first CCA in two cases [(1).when other perform the second CCA, (2).when other wait for ACK], the case of performing the first CCA at one of the above two cases, the number of busy slots out of the backoff slots counted, the normalized energy consumption which is the average energy consumption to transmit one slot amount of payload, Energy consumption to transmit, energy consumption to receive, the energy consumption, the turnaround time, the consumed energy for the successful transmission, the consumed energy for the collision.
Model Validation :
– 2,4 Ghzfrequency channel
– macMinBE = 3, aMaxBE = 5, macMaxCSMABackoff = 4.
– packet length = 7 and 13 slots
– overhead (header and footer) in each packet = 1.5 slots
Thoughput and Energy Consumption Analysis of IEEE 802.15.4 Slotted CSMA/CA.
By T.R Park, T.H Kim. J.Y. Choi, S. Choi and W.H. Kwon
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October 16, 2008
High Speed Network Lab