Throughput comparison of random access methods for M2M service over LTE networks

It is one of the key issues in the 4-th generation (4G) cellular networks how to efficiently handle the heavy random access (RA) load caused by newly accommodating the huge population of Machine-to-Machine or Machine-Type Communication (M2M or MTC) customers/devices. We consider two major candidate methods for RA preamble allocation and management, which are under consideration for possible adoption in Long Term Evolution (LTE)-Advanced. One method, Method 1, is to completely split the set of available RA preambles into two disjoint subsets: one is for human-to-human (H2H) customers and the other for M2M customers/devices. The other method, Method 2, is also to split the set into two subsets: one is for H2H customers only whereas the other is for both H2H and M2M customers. We model and analyze the throughput performance of two methods. Our results demonstrate that there is a boundary of RA load below which Method 2 performs slightly better than Method 1 but above which Method 2 degrades throughput to a large extent. Our modeling and analysis can be utilized as a guideline to design the RA preamble resource management method.