Abstract
Machine-to-machine (M2M) communications allow multiple devices to communicate directly without human intervention. There will be a huge number of devices in the M2M communications which results in enormous congestion in the current Random Access Channel (RACH) of LTE based cellular systems. This paper presents a protocol for improving the performance of the LTE RACH for M2M applications. This protocol, the Distributed Queuing Access for LTE (DQAL), is based on the Distributed Queuing (DQ) algorithm. One of the benefits of using that algorithm is minimizing the collision in the access phase for the M2M communications. The reduction in the collision will turn in enhancing both the access success probability and the access delay for M2M devices (MDs). Furthermore, the protocol is designed to guarantee that the normal User Equipment (UE) device can access the system using the traditional RACH procedures without any modification. This will assure a seamless implementation of the proposed protocol over the existing LTE cellular systems. The simulation results show how the access delay obtained by the proposed DQAL protocol outperforms the Extended Access Baring (EAB) which is the baseline solution recommended by the 3 GPP for M2M communication.
Highlights
The current implementation of the Random Access Channel in the LTE and LTE-A is suffering from high congestion when there are huge numbers of devices trying to access the network
We will study the impact of the selected number of preambles (Np) value on Ps, Da and the collision probability Pc, which is defined as the ratio between the number of occurrences when two or more M2M devices (MDs) send the same preamble and the overall number of access opportunities
The value of Np is selected based on the number of the MDs in order to optimize the access delay according to the chosen constraint
Summary
The current implementation of the Random Access Channel in the LTE and LTE-A is suffering from high congestion when there are huge numbers of devices trying to access the network. The M2M communications introduced a massive number of access requests that can overload the access channel of the current LTE network This leads to an increase in the collision probability and produces a significant access delay [1]. This massive number of M2M devices has to be considered in the design of LTE Random Access Channel (RACH) procedures. Access class barring (ACB) [4] is based on defining 16 different classes with different priorities for accessing the Mobile Information Systems
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