Providing reliable and efficient multicast services is one of the most important issues of the emerging 5G network. As the number of users grows rapidly, non-feedback multicast schemes are more suitable for bandwidth efficiency. However, conventional non-feedback multicast solutions, like the well-known Random Linear Network Coding (RLNC) and Systematic Network Coding (SNC), are suffering from complicated packet decoding and redundant packet reception at the unsaturated users. In this paper, we propose a reliable Hybrid Systematic Network Coding (HSNC) scheme to fully solve these problems. HSNC utilizes both deterministic and randomly generated coding vectors over the same finite field. By subtracting coding vectors with zero elements from a Reed- Solomon coding matrix, the goal to maximize the number of linear independent rows of a coding matrix can be easily realized. Close-form expressions of bit overhead ratio, decoding probability and computational cost are derived out. Numerical results show that HSNC, with or without a sliding window, outperforms RLNC and SNC in terms of the decoding probability. Moreover, HSNC has lower bit overhead and computational cost.

Hardware impairments, such as phase noise, quantization errors, non-linearities, and noise amplification, have baneful effects on wireless communications. In this paper, we investigate the effect of hardware impairments on multipair massive multiple-input multiple-output (MIMO) two-way full-duplex relay systems with amplify-and-forward scheme. More specifically, novel closed-form approximate expressions for the spectral efficiency are derived to obtain some important insights into the practical design of the considered system. When the number of relay antennas N increases without bound, we propose a hardware scaling law, which reveals that the level of hardware impairments that can be tolerated is roughly proportional to √N. This new result inspires us to design low-cost and practical multipair massive MIMO two-way full-duplex relay systems. Moreover, the optimal number of relay antennas is derived to maximize the energy efficiency. Finally, Motor-Carlo simulation results are provided to validate our analytical results.

In this paper, we pursue a detailed outage probability analysis of multihop relaying systems taking into account the practical constraint of cochannel interferences (CCIs). Different from previous works, both relaying transmission and CCIs are performed over generalized -μ fading channels. For both independent identically and non-identically distributed -μ faded CCIs, the exact end-to-end signal-to-interference ratio expressions of the multihop relaying system are obtained. Moreover, we derive new, analytical outage probability expressions of multihop relaying systems in the presence of CCIs. In the high-power regime, simplified expressions are provided, revealing the implications of the channel parameters on the outage performance. These tractable results enable us to draw useful engineering insights about the impact of system and channel parameters on the outage probability of multihop relaying systems. Finally, simulation results are provided to validate our derived expressions.

The massive amounts of machine-type user equipments (UEs) will be supported in the future fifth generation (5G) networks. However, the potential large random access (RA) delay calls for a new RA scheme. Motivated by the key idea of non-orthogonal multiple access, the non-orthogonal random access (NORA) scheme is proposed in this paper to alleviate the access congestion problem. Specifically, NORA utilizes the difference of time of arrival to identify multiple UEs with the identical preamble, and enables power domain multiplexing of collided UEs in the following access process, while the base station performs successive interference cancellation (SIC) based on the channel conditions obtained through preamble detection. Our analysis shows that the performance of NORA is superior to the conventional orthogonal random access (ORA) scheme in terms of collision probability and throughput. Simulation results verify our analysis and further show that our NORA scheme can improve the number of the supported UEs by more than 30%. Moreover, the access delay for successfully accessed UEs are also reduced significantly by using the proposed random access scheme.

The satellite relaying system is a promising network architecture in next generation wireless communication systems, due to its large coverage and stability. In this paper, the performance of a dual-hop decode-and-forward based satellite relaying system over κ-μ shadowed fading channels is investigated, where a source earth station transmits information to a destination earth station via a satellite relay. We first obtain the exact closedform expressions of the outage probability of such a system in terms of bivariate confluent hypergeometric functions. By using a novel gamma approximation to the κ-μ shadowed distribution, the simple outage expression is derived. Moreover, the accurate expression of the average bit error rate (ABER) and the ergodic capacity are obtained in terms of Appell hypergeometric functions and hypergeometric functions, respectively. Again, with the help of the gamma approximation, we derive the approximate ABER and capacity expressions. In the high signal-to-noise ratio regime, the asymptotic ABER expression is obtained in terms of elementary functions. Finally, numerical and Monte-Carlo simulation results are provided to demonstrate the validity of the proposed unified expressions.

The frequency scarcity imposed by fast growing demand for mobile data service requires promising spectrum aggregation systems. The so-called higher order statistics (HOS) of the channel capacity is a suitable metric on the system performance. While prior relevant works have improved our knowledge on the HOS characterization of spectrum aggregation systems, an analytical framework encompassing generalized fading models of interest is not yet available. In this paper, we pursue a detailed HOS analysis of κ-μ and κ-μ shadowed fading channels by deriving novel and exact expressions. Furthermore, the simplified HOS expressions for the asymptotically low and high signal-tonoise regimes are derived. Several important statistical measures, such as amount of fading, amount of dispersion, reliability, skewness, and kurtosis, are obtained by using the HOS results. More importantly, the useful implications of system and fading parameters on spectrum aggregation systems are investigated for channel selection. Finally, all derived expressions are validated via Monte Carlo simulations.

This paper presents an analytical model for analyzing the performance of the TDMA-based distributed reservation protocol for wireless multi-hop ad hoc networks. A novel three-way handshake process is presented which considers the hold-off and competition process before the transmission of scheduling messages. An explicit expression of expectation of the average delay of the three-way handshake process is further derived. Regarding throughput, the concepts of forwarding traffic and pseudo-collision traffic are brought up to evaluate the MAC layer effective throughput. The forwarding characteristic of multi-hop ad hoc networks is studied to calculate the forwarding traffic while the pseudo-collision traffic is derived based on the premise that the nodes are not allowed to transmit while their one-hop neighbors receive. An analytical model which jointly considers the impacts of network parameters, scheduling parameters and frame structure design is constructed. The optimal number of control slots that maximizes the effective throughput is further obtained under certain traffic volume, node density and hold-off exponent. Simulation results show the effectiveness of the theoretical model. The upper bound of MAC layer effective throughput under different network settings is presented.