Performance Analysis And Optimization Of MTC Random Access

Machine type communication (MTC) defined as machine to machinecommunication over cellular mobile network, is an integral part of future ubiquitousnetwork and has broad application prospects and great market potentials.3GPP LTE aslong-term evolution technology of the future mobile communication, has advantages ofhigher data transmission rate, lower transmission delay and larger system coverage. LTEis bound to be the ideal bearing network of MTC services in the future. However, thecharacteristics of MTC services are quite different from H2H (human to human)services, existing poisson traffic model is no longer suitable for MTC modeling. Due toa huge amount of MTC terminals accessing network, it will cause system congestionand long access delay which will bring great challenges to LTE networks on their designand management. Therefore, it has important theoretical significance and practical valuehow to optimize3GPP LTE networks to promote the rapid application of MTC.In response to these issues, this paper sets up two queueing models, and presents aselective admission control solution based on priority and proportional integrativederivative (PID) controller after the in-depth analysis of priority and proportion accessmechanisms. The main research contents and innovations are as follows:①Because existing poisson distribution is inappropriate for MTC trafficmodeling, this paper sets up two queueing models with the assumption that MTCservices arrival interval obeys Beta distribution proposed by3GPP. One is Beta/M/1queueing model, which is used for MTC terminals; another is Hybrid/M/1queueingmodel, which is used for H2H and MTC terminals. The numerical experiments showthat the introduction of M2M services can lead to long delay of H2H communicationand system performance degradation.②In terms of the issues of network congestion and quality of H2Hcommunication degradation that caused by a huge number of MTC terminals, this paperfirst analyzes priority and proportion access mechanisms to guarantee the quality ofH2H communication. Priority access mechanism sets H2H services as high priority, andproportion access mechanism compares and analyses the impact on H2Hcommunication with different ratios of MTC terminals accessing. The numericalexperiments show that priority mechanism can reduce the average access delay of H2Hcommunication effectively, lower proportion of MTC terminals is beneficial to reduce the access delay of H2H communication. Furthermore,this paper presents a selectiveadmission control solution to alleviate the network congestion. This solution selectivelyrejects terminals to access network following an reject probability that is set based onthe designed PID controller, and sets H2H communication as high priority. Thenumerical experiments show that the proposed is simple and reliable, avoiding networkcongestion diffusion. When H2H terminals to MTC terminals which access network is9:1, and service rate is less than the arrival rate, queue length is stabilized nearexpectation, quality of H2H communication is ensured, MTC terminals access delayreduces by14%.