It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

https://link.springer.com/content/pdf/10.1057%2Fjors.1977.206.pdf

Multiple Hypergeometric Functions and Applications

In this paper, a new non-stationary Vehicle-to-Vehicle (V2V) channel model is proposed. It could generate more smooth fading phase between the adjacent channel states and guarantee more accurate Doppler frequency, which is a great improvement comparing with those of the existing non-stationary geometry-based stochastic models (GBSMs) for V2V channels. Meanwhile, the spatial–temporal correlation function (STCF) as well as a temporal correlation function (TCF) and a spatial correlation function (SCF) are derived in details based on the power angle spectrums of both the mobile transmitter (MT) and mobile receiver (MR) following the Von Mises Fisher (VMF) distribution. Simulation results have demonstrated that the time-variant correlation properties of our proposed channel model have an excellent agreement with the theoretical results, which verifies the correctness of theoretical derivations and simulations. Finally, the TCF and stationary interval of the proposed model are verified by the measured results.

A Novel 3D Non-Stationary Vehicle-to-Vehicle Channel Model and its Spatial-Temporal Correlation Properties

On the Double Doppler Effect Generated by Scatterer Motion

In this paper, we focus on the problem of planning heterogeneous cellular networks powered by renewable energy sources, which are a good alternative for dealing with the growth of mobile data traffic while minimizing energy consumption. The paper proposes a method based on a coalitional game in which small cells are players, with the Shapley value determining the contribution of each potential small cell to the global performance of the system. The characteristic function of the game is based on three key performance indicators: percentage of users served, reduction of grid consumption, and average transmission rate. The success of the coalitional game-based planning process is considered from an energy efficiency perspective, which means a reduction of on-grid consumption and an improvement of network performance according to renewable energy availability. The efficiency of the coalitional design is compared with other heuristic and optimal alternatives in two simulation examples. Our results show that the proposed coalitional planning scheme produces an efficient use of energy compared to other strategies.

Coalitional Planning for Energy Efficiency of HetNets Powered by Hybrid Energy Sources

Connected vehicles have received much attention in recent years due to their significant societal benefit and commercial value. However, a suitable channel model for vehicle-to-vehicle (V2V) communications is difficult to build due to the dynamic communication environment. In this paper, a three-dimensional (3D) geometrical propagation model that includes line-of-sight (LoS), single bounced (SB), and multiple bounced (MB) rays is proposed. Each of multiple scatterers in the model is moving with a random velocity in a random direction. Based on the geometrical propagation model, a generalized 3D reference model for narrowband multiple-input-multiple-output (MIMO) V2V multipath fading channels is developed. The corresponding space-time correlation functions (ST-CFs), time correlation functions (T-CFs), and space correlation functions (S-CFs) are analytically investigated and numerically simulated in terms of various factors. Several notable ST-CFs for V2V and fixed-to-mobile (F2M) communications become the special cases of ST-CFs of the proposed model by adjusting the corresponding channel parameters. Finally, the theoretical results of the space-Doppler power spectral density (SD-PSD) are compared with the available measured data. The close agreements between the theoretical and measured SD-PSD curves confirm the utility and generality of the proposed model.

/pdf/three-dimensional-vehicle-to-vehicle-channel-modeling-with-ezvusyvj6k.pdf

Three-Dimensional Vehicle-to-Vehicle Channel Modeling with Multiple Moving Scatterers

The invention discloses a base station planning method for cooperative communication. Different from a fact that cells in the conventional base station planning are regular and free of overlapped coverage, overlapping in different degrees of the base station coverage area of the cooperative communication is produced. According to the scene, the base station planning method comprises the following steps of: establishing an optimization model of base station site location and quantity selection by taking the minimum total power consumption and the minimum quantity of the base station as a target; and giving a numerical solution method of the established model by combining a grid self-adaptive direct search algorithm with a successive elimination method. According to the numerical results, the model can be used for effectively lowering the total power consumption and the quantity of the base station on the premise of guaranteeing the link quality, and verifying the effectiveness of the algorithm and the intrinsic advantages of cooperative communication. The relevant conclusions can provide reference for the base station planning problem of the cooperative communication network.

Base station planning method for cooperative communication

Through decreasing inter-cell interferences, CoMP (Coordinated Multi-Point) can enhance system capacity and spectral efficiency of cell-edge users significantly. BSs (Base stations) are the front-end accesses of CoMP and their planning influences the overall performance of the system directly. Different from the traditional cellular network, the coverage of BSs in CoMP always overlaps with each other to some degree. In order to investigate the BSs planning for CoMP, this paper builds two optimization models to obtain the location and the number of the BSs. A joint optimization algorithm is proposed to solve models, in which the methodologies of mesh adaptive direct search and successive elimination have been used. Numerical results show that the proposed models can effectively reduce the total transmission power and the number of BSs without losing the quality of service for users, which verifies the effectiveness of the proposed algorithms and the inherent advantage of CoMP.

Optimal base stations planning for Coordinated Multi-Point system

The high demand for multimedia applications in environmental monitoring, invasion detection, and disaster aid has led to the rise of wireless sensor network (WSN). With the increase of reliability and diversity of information streams, the higher requirements on throughput and quality of service (QoS) have been put forward in data transmission between two sensor nodes. However, lower spectral efficiency becomes a bottleneck in non-line-of-sight (NLOS) transmission of WSN. This paper proposes a novel nondata-aided error vector magnitude based adaptive modulation (NDA-EVM-AM) to solve the problem. NDA-EVM is considered as a new metric to evaluate the quality of NLOS link for adaptive modulation in WSN. By modeling the NLOS scenario as the η - μ fading channel, a closed-form expression for the NDA-EVM of multilevel quadrature amplitude modulation (MQAM) signals over the η - μ fading channel is derived, and the relationship between SER and NDA-EVM is also formulated. Based on these results, NDA-EVM state machine is designed for adaptation strategy. The algorithmic complexity of NDA-EVM-AM is analyzed and the outage capacity of NDA-EVM-AM in an NLOS scenario is also given. The performances of NDA-EVM-AM are compared by simulation, and the results show that NDA-EVM-AM is an effective technique to be used in the NLOS scenarios of WSN. This technique can accurately reflect the channel variations and efficiently adjust modulation order to better match the channel conditions, hence, obtaining better performance in average spectral efficiency.

A Novel Adaptive Modulation Based on Nondata-Aided Error Vector Magnitude in Non-Line-Of-Sight Condition of Wireless Sensor Network.

In C-V2X (cellular vehicle-to-everything) communication networks, dense spatial reuse of the available radio spectrum is required to achieve efficient spectral usage. Spectrum reuse causes severe network interference where signals from many undesired transmitters are aggregated at a receiver. This paper investigates the 3D spatial characteristics of C-V2X communication interference in the angular domain. A 3D GIDM (Gaussian interference distribution model) is proposed, and the corresponding interference APD (angular power density) is given. Then, the closed-form expressions of some key spatial statistics of interference are derived based on the interference APD. Finally, the closed-form expressions of the probability density function and spatial correlation function of SIR (signal–to–interference ratio) are derived based on the 3D multipath APD model and spatial statistics of the Rice channel. Simulation analysis shows that 3D spatial angular directions have significant effect on these spatial statistics of interference and the spatial correlation function of SIR. The results provide useful insight on the analysis and design of the interference-limited networks.

/pdf/3d-spatial-characteristics-of-c-v2x-communication-2z1foq5kqg.pdf

Derong Du

Papers

Three-Dimensional Vehicle-to-Vehicle Channel Modeling with Multiple Moving Scatterers

Base station planning method for cooperative communication

Optimal base stations planning for Coordinated Multi-Point system

A Novel Adaptive Modulation Based on Nondata-Aided Error Vector Magnitude in Non-Line-Of-Sight Condition of Wireless Sensor Network.

3D Spatial Characteristics of C-V2X Communication Interference