Sha Xuejun

Pulse shaping method to compensate for antenna distortion in ultra-wideband communications

In the ultra-wideband (UWB) communication systems, a critical spectral mask is released to restrict the allowable interference to other wireless devices by the Federal Communications Commission (FCC), and then some pulse shaping methods have been presented to fulfil the mask. However, most pulse shaping methods do not consider the antenna distortion which cannot be neglected in the UWB communication systems compared with the conventional systems. To this end, an orthogonal wavelet based pulse shaping method is proposed in this paper to integrate compensation of antenna distortion into pulse shaping. Simulation results show that the novel pulse shaping method can be used to achieve compensation for antenna distortion, optimization of transmission power spectrum, and simplification of the algorithm, as well as simple implementation of the pulse generator.

Performance of physical-layer network coding in asymmetric two-way relay channels

In this paper, we study the performance of physical-layer network coding in asymmetric two-way relay channels using four different cases having different poor channels: phase asymmetry, downlink asymmetry, uplink asymmetry and node asymmetry. The decision and mapping rule for symmetric and asymmetric cases are studied. The performance in terms of bit error rate for each case will be studied and analysed by computer simulation. Analytical and simulation results show that uplink asymmetry is the worst case; intra-phase asymmetry and unreliable uplink channels will more severely affect the performance degradation, which is caused by channel asymmetry.

A Novel Scheme and Access Architecture for Joint Radio Resource Management in Heterogeneous Networks

In this paper, a access architecture for joint radio resource management (JRRM), hierarchical architecture, is given after analyzing advantage and disadvantage of the existing architectures, which is consider as one of architectures the future heterogeneous radio networks most possibly uses .Then a novel scheme is proposed based on this hierarchical architecture and the work flow of it is discussed in detail. The innovation of this scheme is that dynamic spectrum management (DSM) is integrated into the existing JRRM schemes based on predicting traffic in every radio access technology’s(RAT) cells. In order to evaluate performance, a new concept, spectrum utility, is used which reflects degree and efficiency of resources utilization. Compared with the JRRM without DSM, this scheme can improve spectrum utility and reduce blocking rate.

Secret Communication Using Parallel Combinatory Spreading WFRFT

In this letter, a parallel-combinatory-spreading-based weighted fractional Fourier transform (PCS-WFRFT) system aiming to guarantee physical layer (PHY) security is proposed. In this system, the transmission data are first divided into two groups. Based on the first group of data, a set of pseudonoise sequences is generated and then used to spread and encrypt the second group of data. In general, the proposed system is spread and dynamically encrypted by the message information itself, whereby both high bandwidth efficiency and high security performance are obtained. Numerical simulations are conducted to evaluate the performance of the proposed system in terms of the average bit error rate.

A Novel JRRM Approach Working Together with DSA in the Heterogeneous Networks

Joint Radio Resource Management (JRRM) and Dynamic Spectrum Allocation (DSA) are both promising approaches in the heterogeneous networks to increase overall QoS and spectrum efficiency, which have already been taken into the framework of heterogeneous radio access networks of E2R. However, not much research has been done about how they could work together properly. In our opinion, JRRM should act according to the spectrum arrangement and planning of DSA among different RATs. This paper gives the load situation a new expression, through which JRRM would be informed of not only the load respected with the RAT considered but also the DSA’s planning about the spectrum and traffic distribution among RATs. JRRM could act in accordance with DSA. Simulative comparison demonstrates that the JRRM proposed in this paper performs better than the original JRRM when working together with DSA in heterogeneous scenarios.

An Energy-Efficient Message Passing Approach in MAC Design for Wireless Sensor Networks

As wireless sensor networks are used more widely, the design of medium access control protocol will be largely various. The paper reviews Sensor MAC (S-MAC), which is the basic MAC protocol for wireless sensor networks, and points its advantages and disadvantages. Several improving S-MAC protocols that focus on different problems in S-MAC are introduced. The Fragment Indication Message Passing (FIMP), a new energy-efficient message passing approach, is proposed to solve the turnaround consumption problem in S-MAC. It exploits a set of special binary codes to indicate each fragment. Thus, the receiver can easily check the failed fragments. Moreover two ACK packets are used to reduce the possible of retransmission.

Pulse Shaping for UWB Communications in Dense Multipath

For high-speed UWB systems working in dense multipath environments, Inter Pulse Interference (IPI) is a primary obstacle to achieving good performance. The impact of the pulse waveform on the IPI is analysed. The analysis in this paper shows that the IPI becomes the lowest when the spectrum of the waveform is rectangular in pass band. For practical considerations, the spectrum of the waveform is restricted by the spectral mask and the distribution of energy of pulse should be concentrated in a time slot, so a compromise should be made between these issues in waveform design. The optimal pulse waveform restraining the IPI, which is meanwhile compliant with the FCC spectral mask, is designed as an example.For high-speed UWB systems working in dense multipath environments, inter pulse interference (IPI) is a primary obstacle to achieving good performance. The impact of the pulse waveform on the IPI is analysed. The analysis in this paper shows that the IPI becomes the lowest when the spectrum of the waveform is rectangular in pass band. For practical considerations, the spectrum of the waveform is restricted by the spectral mask and the distribution of energy of pulse should be concentrated in a time slot, so a compromise should be made between these issues in waveform design. The optimal pulse waveform restraining the IPI, which is meanwhile compliant with the FCC spectral mask, is designed as an example

MANET Routing Protocols Comparison for Composite Traffic Network

The choice of routing protocols is an important issue in the establishment and design of Ad hoc networks. However, existing routing protocols are based on single traffic source or simple traffic models used in conventional networks like HTTP and video flows. In this paper we focus on choosing routing protocols for network with a composite traffic model that is closer to the real situation. This paper compares two common mobile ad hoc network (MANET) routing protocols, i.e., AODV and TORA in terms of both traffic delay and traffic deliver rate, in networks with different node mobility. Simulation results manifest that TORA outperforms AODV in the traffic deliver rate in all the scenarios. The best traffic deliver rate of TORA is 73.9% in static network. When the nodes in network are static, TORA excels AODV in traffic delay. However, when the nodes move, the traffic delay of AODV improves from 42.60s to 4.56s and is lower than that of TORA.

TOA Estimate Algorithm Based UWB Location

Combining with UWB location technology, TOA location algorithm is presented. The first step is statistically averaging the received signals to mitigate impact of AWGN as long as possible. Using incoherent power detection algorithm obtain rude TOA estimation which is made incoherent power detection once more in the second step so as to further optimize in time. The simulation results show that the algorithm under low computational complexity can effectively improve ranging performance and location precision.

Interference Mitigated Receiver Based on Base Station Cooperation

Base station cooperation can mitigate interference of other cell in the uplink, in this paper future base stations cooperation architecture and information exchange scheme are proposed, receiver based on base station cooperation is designed, each station detected the weak signal information of users, which are transmitted to cooperative base station to combine and send demodulated signal to local base station. Meanwhile, in receiver, cooperation priority is analyzed which can reduce delay and improve throughput. The proposed receiver can efficiently mitigate OCI to improve system performance, providing new ideas for base station cooperation applying to realistic network.