Algorithm Study On M2M Communication Random Access

M2M Communication refers to the interconnection and communication betweenmachines. It guarantees the data exchange among machines and devices throughwireless communication and back-end server. M2M has huge impact on the currentnetwork due to its huge amount of terminals. This paper chooses M2M load controlaccess algorithm as the research object, which handles the wireless congestion causedby M2M application.The characteristic of having a large number of terminals in M2Mcommunication determines that a competition-based random access mechanism isoptimal. For the necessity of competition in the shared channel, the existing randomaccess algorithms have a major drawback. That is, they work well under certaintraffic load, but the channel competition and collision get more serious as the trafficload increase. The throughput could decreases dramatically even to0. Therefore, newaccess algorithms with traffic load control mechanism are required to solve theserious collision. The key idea to handle this is by introducing a new transmissionprobability parameter through the channel’s statistic information. Considering M2M’sfeatures under cellular network and WLAN, we design the corresponding randomaccess algorithms with traffic load control.In cellular based M2M communication, we first summarize the characteristics ofadaptive traffic load control access algorithms and the corresponding ATL S-ALOHAand ATL np-CSMA algorithms. Subsequently, a compromised algorithm named ATLS-MACA is introduced. No carry sensing module is needed in ATL S-MACA and itcould achieve much better performance compare to ATL S-ALOHA. Both analysisand simulation results prove its advantage.In WLAN based M2M communication, considering that there are finite numberof stations with saturation data, we proposed a modified access mechanism namedConstrained-send DCF (CDCF). To constrain stations’ transmission, we introduced aconstrained-send probability at the end of each backoff procedure. Numerical resultsshow that the CDCF mechanism has much better performance than DCF both in throughput and average packet delay. The CDCF keeps all the features of theIEEE802.11DCF protocol and is quite easy to implement. It is suitable for M2Mapplications access.Finally, to be more realistic, we consider the fact that the number of stations inWLAN may be unknown to the AP and we have designed two correspondingenhancements of CDCF. One is to estimate the number active nodes. We summarizeboth the data frame listening and conditional collision probability based estimationmethods. Taking the complexity of estimation algorithm into account, we presentanother algorithm named D-CDCF. In D-CDCF, we first find the channel occupancyrate under the optimal condition, which is a quasi-invariant. Then through carriersensing, the algorithm dynamically adjusts the transmission probability parameter totune the system to work under that condition.