Non-orthogonal random access method in large-scale M2M network based on optimal power backoff

Abstract

The invention discloses a non-orthogonal random access method in a large-scale M2M network based on optimal power backoff, and the method comprises the following steps that 1), a base station increases the ACB factor by the times of an optimal number MTCD 1* and sends the increased ACB factor to all MTCDs, and the MTCD that passes the ACB test sends a first message Msg1 to the base station througha physical random access channel, determines the number of MTCDs that select the same PA, i.e., the number of MTCDs that initiate random access attempts in a current access slot; 2), the base stationsends a second message Msg2 to the MTCDs according to all selected PAs, and the MTCDs monitor the RAR represented by RA-RNTI on the PUSCH (physical downlink control channel); 3), the MTCD capable ofmonitoring the RAR transmits a third message Msg3 according to the selected tag PA, and each MTCD of the same PA achieve the NOMA on the same PUSCH through the multiplexing of the power domain; 4), the base station uses the SIC to decode a data packet on the PUSCH, and sends a fourth message Msg4 to the successfully decoded MTCD. This method can effectively improve the system throughput and reducethe access delay of equipment.

Description

technical field [0001] The invention belongs to the technical field of random access in large-scale M2M networks, and relates to a non-orthogonal random access method based on optimal power backoff in large-scale M2M networks. Background technique [0002] As the main communication platform of the Internet of Things, M2M has become the main communication scenario of 5G. 3GPP defines the M2M communication method for data transmission through a cellular network as Machine Type Communication (MTC). However, there are three key problems in the deployment of M2M in cellular networks: First, due to the huge number of machine-type communication devices (MTCDs), a large number of event-triggered MTCDs use contention-based bursts on the physical random access signal (PRACH) in a short period of time. Sending random access (RA) will cause access collisions, resulting in network congestion and large delays; secondly, because the total amount of communication data is huge but the amoun...

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Problems solved by technology

However, there are three key problems in the deployment of M2M in cellular networks: First, due to the huge number of machine-type communication devices (MTCDs), a large number of event-triggered MTCDs use contention-based bursts on the physical random access signal (PRACH) in a short period of time. Sending random access (RA) will cause access collisions, resulting in network congestion and large delays; secondly, because the total amount of communication data is huge but the amount of single data is small, if MTCD first establishes with the base station through random access The communication method of connecting and retransmitting data not only causes serious signaling overhead between MTCD and the base station, but also reduces the utilization rate of system resources; finally, due to limited wireless resources, there is a problem of reasonable allocation of time-frequency resources

However, these studies cannot fundamentally solve the problems of mM2M network congestion and other issues. In view of the advantages of non-orthogonal multiple access technology, some people propose to use power domain multiplexing to make colliding devices into a NOMA group. This method greatly alleviates network congestion. , improving system throughput and reducing access delay

However, this method only proposes a framework, and does not study in depth how power domain multiplexing can obtain the maximum throughput, nor does it combine ACB mechanism to make adjustments so that the system can give full play to the advantages of power domain multiplexing and further improve throughput volume, reducing access delay

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