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System modeling and performance analysis are nontrivial issues in satellite networks. Mainstream methods model the acquire-store-forward process of traffic as a queuing process, where the transmitter and buffer work as the server and queue, respectively. However, the intermittent connectivity of satellite links hampers the direct employment of traditional vacation policies, because the inactive period of link is independent of the buffer state. Hence, we propose a time-limited M/G/1 model for the intermittent transmission among satellites. Furthermore, we derive the steady-state expressions and lower bound of performance parameters by transient analysis. Finally, simulation results verify the effectiveness of our method.

In this letter, the closed form sum rate for the random beamforming is analyzed over the downlink multiple-input single-output and multiple input multiple-output interfering broadcast channel with finite users. The analysis approach is based on the limiting throughput distribution theorem, and can be applied for the multi-cell interference scenarios with heterogeneous signal to interference-plus-noise ratio (SINR) distributions and user schedule probabilities. It is proved that both the exact and the asymptotic sum rates achieved from SINR/signal-to-interference ratio analysis will converge to the Gumbel type distribution. The effectiveness of the proposed analytical framework is confirmed by simulation results.

As an appealing interference management approach, interference alignment (IA) has not been intensively studied in full-duplex (FD)-based multi-cells. In this letter, based on Bezout’s theorem, we explore the feasibility conditions of IA in small cell networks, where base stations are equipped with FD hardware. The comparison of IA performance between FD and traditional half-duplex small cells in terms of the total degrees of freedom (DoFs) is also conducted. We find that the IA performance with FD is limited by the number of antennas at users. Furthermore, we verify that IA with opportunistic FD can be implemented to achieve higher total DoFs of the network.

In this letter, we have investigated the frequency diversity gain of a sparse code multiple access (SCMA) system to improve spectrum utilization by exploiting the codebook correlation in the SCMA system. To this end, a backtracking codebook matching (BCM) algorithm is proposed, whereby there are more successfully scheduled users, which are allocated the low-correlated codebooks. Simulation results exhibit the superiority of the BCM algorithm and the impact of codebook correlation on scheduling.

In this letter, we investigate the fundamental tradeoff between rate and energy for sparse code multiple access (SCMA) networks with wireless power transfer. A weighted rate and energy maximization problem by jointly considering power allocation, codebook assignment, and power splitting, is formulated. To solve the hard problem, an iterative algorithm based on the univariate search technique is proposed, which has good performance with low complexity. Specifically, we analyze the special structure of the problem and exploit it to obtain the optimal power splitting ratio and resource allocation strategy when one of them is fixed. Simulation results indicate that our algorithm achieves a better rate-energy tradeoff compared to other schemes.

This letter first presents an incremental amplify-and-forward orthogonal frequency division multiplexing relaying scheme to promote the spectrum efficiency of cooperative transmission. Then, the energy efficiency problem is thoughtfully investigated in order to prolong the lifetime for such battery-operated wireless networks. As will be seen, the original optimization problem incorporating incremental policy, relay selection and power loading is formulated as a mixed-integer nonlinear programming problem that is quite hard to solve even numerically, thereby necessitating our derivation of a suboptimal approach for implementation feasibility. Specifically, by exploiting energy pricing concept as well as max-min energy efficiency criterion, a stepwise energy aware resource allocation algorithm is proposed. Finally, numerical results verify the benefits of our proposals.

In this letter, we propose an opportunistic interference alignment and cancellation (OIAC) scheme for cellular networks to exploit the multi-user diversity gain and the backhual resources among base stations. Particularly, an opportunistic user scheduling strategy is proposed by synthesizing opportunistic interference alignment (OIA) and successive interference cancellation (SIC). In the OIAC scheme, we propose a new user scheduling metric and a sequential user selection scheme based on the characteristics of SIC, and guarantee a target signal-to-interference-plus-noise ratio (SINR) for each selected user by performing user selection, decoder design and power control jointly in the user selection process. The OIAC scheme improves system performance by using SIC and keeps the low implementation complexity property of OIA. The simulation results show that the OIAC scheme can improve the achievable sum rate significantly compared to OIA and other schemes.

Smart interference management has been receiving attention to improve network throughput. Successive interference cancellation (SIC) is one of the promising techniques, which allows multiple concurrent transmissions from different transmitters to the same receiver. We study the scheduling issue with SIC in dense small cells. This paper proposes a novel scheduling framework, which facilitates us to develop practical algorithms to find the solution.

For a three-cell constant cellular interfering network, a new property of alignment is identified, i.e., an interference alignment (IA) solution obtained in a user-cooperation scenario can also be applied to a non-cooperation environment. By using this property, an algorithm is proposed by jointly designing transmit and receive beamforming matrices. Analysis and simulation results show that more degrees of freedom (DoF) can be achieved compared with conventional schemes in most cases.

In this letter, the degrees of freedom (DoF) outer bound is characterized for an L-cell constant cellular interfering network by using linear interference alignment (IA). For a symmetric network, it means that no matter how many cells and users per cell there are, the total achievable DoF is bounded by M+N, where M and N denote the number of antennas equipped on users and base stations. Besides, a DoF achievable algorithm is also proposed. Although the DoF outer bound cannot be reached, more DoF can be obtained compared with orthogonal schemes.

It is shown in (W.G. Song and J.T. Lim, 2006) that the proposed least squares channel estimator for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems will acquire improved performance as the polynomial order increases, which we find is not generally the case. Analyses and simulation results are given to support our claim.

The transmission collisions of topology-transparent reservation time division multiple access protocol with MIMO links are solved by dynamically trading off the MIMO link transmission capacity and its anti-interference ability. Through theoretical analysis, we derive the guaranteed throughput and optimal frame length. Results show that the guaranteed throughput will be improved greatly by dynamic allocation of MIMO transmission capacity and its anti-interference ability. Moreover, the protocol is immune to topology change.

To solve collisions of topology-transparent schedules in multihop ad hoc networks, we propose a topology-transparent schedule with reservation and carrier sense. Our schedule is based on slotted architecture in which each slot is divided into reservation phase and data phase. Each node resolves possible collisions in its assigned slots by reservation and utilizes free ones among its non-assigned slots by carrier sense. By analysis, we derive the optimal parameter for the best performance. Compared results show that our schedule is better than others.

Collision resolution using splitting algorithm is an effective strategy to improve the performance of Medium Access Control (MAC) protocol. In this letter, a novel splitting algorithm, Hybrid Splitting Algorithm (HSA) for wireless MAC, has been presented. The splitting procedure of HSA has related with both the generation time and the generation interval of the colliding packets. The maximum stable throughput of HSA is up to 0.51. As illustrated from the simulation results using both Poisson and Heavy Tail distributed traffic, HSA outperforms binary-tree and FCFS Splitting Algorithm.