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Background: Non-orthogonal multiple access (NOMA) is viewed as the key multiple access technology for 5G and beyond networks, attracting the attention of academics and industries. NOMA and the multiple input multiple output (MIMO-NOMA) technology can improve a system’s throughput, latency, and energy efficiency (EE) in future-generation communication networks. Objective: The objective of this paper is to achieve maximum EE by applying the Max-min Power Control Algorithm (MMPCA) through sub-channel optimization, resource allocation (RA) optimization, access point selection (APS), and user association. The EE results obtained with and without using MMPCA are compared to the RA optimization from a conventional water-filling algorithm (WFA). Method: This paper formulates a framework for user-centric (UC) joint resource allocation, such as backhaul connection via beam-forming and Access point (AP) to user connection via MIMO-NOMA. The user without interference is decoded using the NOMA principle. The MMPCA was also used to optimize cooperative power allocation, sub-channel allocation, and efficient user association. The RA for EE is framed as a mixed non-convex and non-linear function using successive convex approximation and sum ratio decoupling converted into convex and linear. A bisection method was used to achieve optimal RA, user association, and sub-channel assignment. Results and Conclusion: The simulation shows energy efficiency (EE) improvement. Similarly, it is observed that MMPCA outperforms the WFA.

In this article, the user resource allocation and user scheduling in a cell-free user-centric clustering network and coherent transmissions is investigated. However, the setup of the user-centric clustering is not sufficient for multi-user transmissions, and user scheduling becomes difficult. To overcome the aforementioned problem and to provide user fairness, an optimum resource allocation algorithm with perfect user scheduling, beam forming, and radio frequency transmitter (RFT) clustering is proposed. Thereby, the cell edge user achieves the optimum throughput and spectrum efficiency. The simulation result shows that the proposed method outperforms the conventional method. In addition, the pilot-reusing factor is used to obtain loss due to imperfect channel state information and pilot train overhead.

Aggressive packet combining (APC) scheme is a well-established scheme which reduces the number of retransmissions for receiving correct packet in error prone wireless link. It is a well-known fact that the retransmissions consume extra bandwidth and battery energy of the portable computer. Therefore, APC is an efficient technique which reduces number of retransmissions for a packet, thus reducing latency of the wireless system. In APC, three copies of a packet are transmitted, and receiver does bit-wise majority decision to get the combined copy. Least reliable bits identification is done in the combined packet if majority logic fails. Search the correct bit pattern for least reliable bits so obtained. APC provides higher reliability but at expense of throughput of the system. Therefore, major issue in APC is the lower throughput which at maximum is 33.33% (\( \frac{1}{3} \times 100 \)). In this paper, modified APC with repetition code is proposed which addresses lower throughput issue of conventional APC. Simulation results show significant performance improvement in terms of throughput when packet combining scheme with repetition code is used in APC scheme.

The two popular techniques of packet combining based error correction schemes are: Packet Combining (PC) scheme and Aggressive Packet Combining (APC) scheme. PC scheme and APC scheme have their own merits and demerits; PC scheme has better throughput than APC scheme, but suffers from higher packet error rate than APC scheme. The wireless channel state changes all the time. Because of this random and time varying nature of wireless channel, individual application of SR ARQ scheme, PC scheme and APC scheme can’t give desired levels of throughput. Better throughput can be achieved if appropriate transmission scheme is used based on the condition of channel. Based on this approach, adaptive packet combining scheme has been proposed to achieve better throughput. The proposed scheme adapts to the channel condition to carry out transmission using PC scheme, APC scheme and SR ARQ scheme to achieve better throughput. Experimentally, it was observed that the error correction capability and throughput of the proposed scheme was significantly better than that of SR ARQ scheme, PC scheme and APC scheme.

In an automatic repeat request (ARQ) scheme, a packet is retransmitted if it gets corrupted due to transmission errors caused by the channel. However, an erroneous packet may contain both erroneous bits and correct bits and hence it may still contain useful information. The receiver may be able to combine this information from multiple erroneous copies to recover the correct packet. Packet combining (PC) is a simple and elegant scheme of error correction in transmitted packet, in which two received copies are XORed to obtain the bit location of erroneous bits. Thereafter, the packet is corrected by bit inversion of bit located as erroneous. Aggressive packet combining (APC) is a logic extension of PC primarily designed for wireless communication with objective of correcting error with low latency. PC offers higher throughput than APC, but PC does not correct double bit errors if occur in same bit location of erroneous copies of the packet. A hybrid technique is proposed to utilize the advantages of both APC and PC while attempting to remove the limitation of both. In the proposed technique, applications of APC-PC on Gilbert two state model has been studied. The simulation results show that the proposed technique offers better throughput than the conventional APC and lesser packet error rate than PC scheme.

Aggressive Packet combining scheme is very efficient technique for error correction in wireless data communication. Transmitter transmits three copies of the original packet. Receiver applies bit by bit majority voting on the received erroneous copies and gets the original packet. The major limitation of APC is that, if the bit error occurs in the same bit location of all the received copies then APC fail to correct them which results in reduced correction capability and reduced throughput. In this paper, a new modified APC technique is proposed that can eliminate the major limitation of the APC by using half-byte packet reverse technique and even & odd selection method thus increasing correction capability and throughput. General Terms Correction capability, odd-even selection, packet reverse technique.

Aggressive Packet Combining (APC) scheme is well established for receiving correct packet in high error prone wireless link. In APC three copies of a packet are transmitted and receiver does bit wise majority decision to get the correct copy. The main research challenge in APC is that if two or more copies of the packet become erroneous at the particular bit location then majority logic fails to correct the error and also as three copies of packet are sent at a time, throughput degradation takes place at higher error rate channel. In this paper we propose a new method of correction in APC which will address the limitation which occurs in conventional APC. General Terms Throughput comparison

Aggressive Packet Combining (APC) scheme is well established for receiving correct packet in high error prone wireless link. In APC three copies of a packet are transmitted and receiver does bit wise majority decision to get the correct copy. The main research challenge in APC is that if two or more copies of the packet become erroneous at the particular bit location then majority logic fails to correct the error. In this paper we propose a new method of correction in APC which will address the limitation which occurs in conventional APC. General Terms Error correction capability

Aggressive Packet Combining (APC) scheme proposed by Leung for error correction in wireless data network is an established research topic. APC is an application of error correction protocol at receiver under ARQ (Automatic Repeat Request) protocol and is found as an appropriate technique for high bit rate wireless channel. Several modifications were studied earlier for improving throughput, decreasing latency and minimizing the bandwidth utilization etc elsewhere. APC as proposed by Leung suffers many disadvantages and the major two disadvantages are that of the low throughput and failure of the scheme to correct error occurring at same bit location of two or more received copies of the packet. To address the stated drawback of the APC, we proposed a technique called Logical Aggressive Packet Combining (LAPC) with Post-reception Selection combining in this paper. And LAPC with PRSC is found to eliminate the above stated disadvantages of APC.