Yanzan Sun

A method for pico-specific upper bound CRE bias setting in HetNet

Heterogeneous Networks (HetNet) consisting of Macrocells deployment and overlaying Picos provide an attractive way to improving the Macrocell capacity and coverage. However, the inter-tier interference from Macrocell to Pico in such two-tiers system can significantly reduce the coverage of Pico and cause the system capacity loss. So, the Cell Range Expansion (CRE) for Pico with Almost Blank Subframe (ABS) configuration for Macrocell is proposed in 3GPP to improve the coverage of Pico. Based on this background, we proposed an estimation algorithm for Pico-specific upper bound CRE bias calculation which can ensure the SINR requirement for Pico User Equipments (PUEs).

Energy Efficiency Maximized Resource Allocation for Opportunistic Relay-Aided OFDMA Downlink with Subcarrier Pairing

This paper studies the energy efficiency (EE) maximization for an orthogonal frequency division multiple access (OFDMA) downlink network aided by a relay station (RS) with subcarrier pairing. A highly flexible transmission protocol is considered, where each transmission is executed in two time slots. Every subcarrier in each slot can either be used in direct mode or be paired with a subcarrier in another slot to operate in relay mode. The resource allocation (RA) in such a network is highly complicated, because it has to determine the operation mode of subcarriers, the assignment of subcarriers to users, and the power allocation of the base station and RS. We first propose a mathematical description of the RA strategy. Then, a RA algorithm is derived to find the globally optimum RA to maximize the EE. Finally, we present extensive numerical results to show the impact of minimum required rate of the network, the user number, and the relay position on the maximum EE of the network.

Energy Efficient Pico Cell Range Expansion and Density Joint Optimization for Heterogeneous Networks with eICIC

Heterogeneous networks, constituted by conventional macro cells and overlaying pico cells, have been deemed a promising paradigm to support the deluge of data traffic with higher spectral efficiency and Energy Efficiency (EE). In order to deploy pico cells in reality, the density of Pico Base Stations (PBSs) and the pico Cell Range Expansion (CRE) are two important factors for the network spectral efficiency as well as EE improvement. However, associated with the range and density evolution, the inter-tier interference within the heterogeneous architecture will be challenging, and the time domain Enhanced Inter-cell Interference Coordination (eICIC) technique becomes necessary. Aiming to improve the network EE, the above factors are jointly considered in this paper. More specifically, we first derive the closed-form expression of the network EE as a function of the density of PBSs and pico CRE bias based on stochastic geometry theory, followed by a linear search algorithm to optimize the pico CRE bias and PBS density, respectively. Moreover, in order to realize the pico CRE bias and PBS density joint optimization, a heuristic algorithm is proposed to achieve the network EE maximization. Numerical simulations show that our proposed pico CRE bias and PBS density joint optimization algorithm can improve the network EE significantly with low computational complexity.

On the Energy Efficiency of On-Off Keying Transmitters with Two Distinct Types of Batteries

As nodes in wireless sensor networks are usually powered by nonrenewable batteries, energy efficient design becomes critical. This paper considers a battery-powered transmitter using on-off keying (OOK) modulation and studies its energy efficiency in terms of the battery’s energy consumption for per bit transmission (BECPB). In particular, the transmitter may use one of two distinct types of batteries with battery utilization factor (BUF) depending on discharge current. The first has an instantaneous discharge current (IDC)-based BUF, while the second has a mean discharge current (MDC)-based BUF. For each type of battery, a closed-form BECPB expression is derived under a Rayleigh channel when a prescribed symbol error rate (SER) is guaranteed. Then theoretical analysis is made to study the impact of battery characteristic parameter γ, communication distance d and bandwidth B on the BECPB. Finally, the analysis is corroborated by numerical experimental results, which reveal that: the BECPB for each type of battery increases with γ and d; the BECPB for the two batteries first decreases and then increases with B, and there exists the optimal bandwidth corresponding to the minimum BECPB; the battery with IDC-based BUF corresponds to a larger BECPB. When γ and d are large, the BECPB for each type of battery is significantly higher than that for the ideal battery whose BUF is aways 1. For instance, when γ=0.015, d=90 m and B=10 kHz, the BECPB for IDC-based and MDC-based battery is nearly 60% amd 25% higher than that of the ideal battery, respectively.

Time allocation optimisation for multi-antenna wireless information and power transfer with training and feedback

Time allocation optimisation for a multi-antenna wireless energy and information transfer system is studied in this study. The terminal first harvests the wireless energy from the base station (BS) during phase I, and then uses the harvested energy to power its information transmission during phase II. Realistic channel state information (CSI) assumptions are made where the CSI at the BS is obtained via training and feedback and is subject to channel estimation error and quantisation error. Therefore, in addition to the tradeoff between information and power transfer, there is also a tradeoff in determining the overheads of training and feedback. To gain insight into this problem, the authors characterise the asymptotic behaviour of the parameters in the large system limit where the number of transmit antennas N t and transmission block length L tot tend to infinity with fixed ratio L tot / N t . The optimal overheads of training and feedback within each phase are first derived to maximise the harvested power and the information transmission rate, respectively. The optimised time allocation between phase I and phase II is then obtained by maximising the bounds of the effective average information transmission rate. Finally, numerical results are presented to verify the proposed theorems.

Grouped Selected Mapping for PAPR Reduction in Optical OFDM Systems

In this paper we propose a grouped selected mapping (G-SLM) scheme for PAPR reduction in optical OFDM (O-OFDM) systems, which improves the PAPR reduction performance and decreases the overhead of side information.

Resource management with multilevel interference mitigation in heterogeneous network

Time domain enhanced intercell interference coordination with Almost Blank Subframe (ABS) configuration for Macrocell is proposed in 3GPP to mitigate the inter-tier interference for heterogeneous networks (HetNets) consisting of Macrocells and overlaying Picos. The existing schemes for ABS power optimization are mainly base on the same level muted power of ABS, which will either cause time-frequency resource waste for Macrocell with zero power ABS or reduce the Pico cell range expansion capability with low power ABS. In this paper, we propose a multilevel power ABS scheme with resource management to conquer these problems. The simulation results show that our proposed scheme can improve the network throughput and protect the cell range expansion (CRE) area user effectively.

Volterra-Model-Based Nonlinear Compensator with Kronecker Product for OFDM-PON System

Nonlinear fiber effects of OFDM-PON systems with coherent detector are investigated. They can be suppressed by Volterra-model-based nonlinear compensator with Kronecker product. Simulations show that the effects can be reduced dramatically.