Fenglin Fu

Inter-cell cooperation aided dynamic base station switching for energy efficient cellular networks

In this paper, a cell zooming based dynamic base stations (BS) switching scheme is conceived for energy saving in cellular networks. A cell zooming algorithm is developed for leveraging the BSs coverage with inter-cell cooperation and downlink power control. Meanwhile, we design a feasible working strategy for the cell zooming scheme to maximizing the energy saving. Simulations are provided to demonstrate the advantages of the proposed scheme.

A novel load balancing scheme in LTE and WiFi coexisted network for OFDMA system

In this paper, a novel load balancing scheme is conceived for the OFDMA LTE cellular and WiFi coexisted network. The mobile index is introduced to measure the mobility of user equipments (UE) in the coverage of WiFi hotspots and the access index is calculated by considering both mobile index and the received power from WiFi access points (AP) to determine the UEs access pattern. The load balance entity manages the UE load in coexistent network dynamically. A load balancing algorithm is developed to balance the network load measured by the ratio of the average WiFi load to the LTE cell load as well as the Jains fairness index. Simulation results demonstrate the proposed algorithm can acquire an improvement in network load balancing, thus enhancing the overall system throughput.

Closed-form symbol error rate expression of decode-and-forward relaying using orthogonal space-time block coding

The authors investigate the symbol error rate (SER) performance of the cooperative decode-and-forward (DF) relaying strategy with orthogonal space–time block coding (OSTBC) applied at all links of source-relay, source-destination and relay-destination. Only when one relay node is able to correctly decode the OSTBC codeword of the source, it will forward source information to the destination with the same OSTBC codeword. The exact SER expressions of DF relaying with OSTBC are presented for M-PSK and M-QAM modulations, respectively, over dissimilar Rayleigh fading channels. By virtue of the multinomial theorem and the law of total probability, the derived expressions are further deduced in closed form. Simulations demonstrate the proposed closed-form analytical results. It is pointed out that such results have seldom appeared in literatures before.

Closed-form expression for outage probability of DF relaying with unequal Nakagami interferers in Nakagami fading

We study the outage performance for the decode-and-forward (DF) relaying in the Nakagami fading under unequal Nakagami interference. A closed-form expression for the outage probability is derived. Simulations are provided to verify the analytical results.

Outage Performance of Cooperative Relay Using STBC Systems

We analyze the outage performance of the cooperative relay with the decode- and-forward protocol under Rayleigh fading channels. The technique of orthogonal space–time block coding is applied at the links of source-relay, source-destination and relay-destination. A closed-form expression for the outage probability is derived. Simulation results demonstrate the theoretical solutions.

Spectrum sharing with smooth supermodular game in cognitive radio networks

In this paper, a supermodular game theoretic approach is investigated for spectrum sharing in cognitive radio networks. We consider a Bertrand competition model, in which primary service providers compete to sell their spare spectrum and then to maximize their individual profits. We demonstrate that the Bertrand competition is a smooth supermodular game, and a round-robin optimization algorithm is developed to obtain the optimal price solutions. Simulation results verify that the algorithm approximately converges to an equilibrium point, and the influence of the exogenous variable on the equilibrium point is analyzed.

Performance Analysis of STBC MB-OFDM UWB

This paper addresses the performance analysis for orthogonal space-time block coded (STBC) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems. As the channel model considers the log-normal fading, the resultant signal to noise ratio (SNR) will be the product of a log-normal distributed variable and a variable of sum of several Gamma-distributed variants. Based on this, the exact expressions for the bit error probability and the outage probability are derived theoretically. And their approximate expressions can be obtained via the Gauss-Hermite and the Gauss-Laguerre quadratures, respectively. Simulation results verify the theoretical solutions.

Distributed link scheduling for congestion control in multihop wireless network

A distributed link scheduling scheme with cross-layer design is conceived based on the physical interference model for controlling the congestion in multihop wireless networks. Link scheduling and nonlinear power control problem are analyzed based on the physical interference model and a distributed algorithm is designed to accomplish the rate allocation and the link scheduling. The algorithm is tested in the case that users randomly arrive at and depart the network following the Poisson Process. Simulation results verify that the network is stable with the proposed algorithm, by which the data rate of each user injected into the network is computed.

Impact of node-selfishness on the connectivity and path delay of Ad-hoc networks

We investigate the impact of the node-selfishness on the network connectivity and the path delay of information dissemination in large scale Ad-hoc networks based on the percolation theory. A network framework with links obeying stationary process is conceived by combining the effects of both node-selfishness and link qualities. The existence of the node cooperation probability boundary is proved when the network density exceeds a value. The network presents two connection characteristics with respect to this boundary. The minimum path delay is asymptotically independent of the source-destination distance when the node cooperation probability exceeds this boundary. While the node cooperation probability is below the boundary, the minimum path delay scales linearly with the source-destination distance. Simulation results verify the theoretical analysis.

Energy-efficient power and subcarrier allocation for OFDMA systems with value function approximation approach

In this paper, we conceive an energy-efficient power and subcarrier allocation scheme for downlink OFDMA systems under average delay constraints. The services associated with multi-users have different packet arrivals and delay requirements. The problem of dynamic power and subcarrier allocation is formulated as a constrained Markov decision process (CMDP) with control actions based on the joint states of channel state information (CSI) and the queue state information (QSI). An online learning algorithm is developed for solving the CMDP problem with the aid of stochastic approximation and the value function approximation approach.