Chen Peipei

Transmission Characteristics of Ultra-Wide Band Impulse Signals

A simplified analytic solution for UWB impulse signal transmitting through a finitely conducting slab is proposed in this paper. To obtain the impulsive transmitting field, either for vertical or horizontal polarization, approximations to the refraction coefficients and propagation loss are made. Thereby, it permits simplified closed-form expressions in the time domain for both terms. The resulting transient response for the transmitting impulse field is then given by convolution of the time domain refraction coefficients and time domain propagation loss. The simulations of incident monocycle transmitting through slabs of different materials and thickness are presented by applying the simplified time domain analytic solution to illustrate the characteristics of transmission and give some results in simplification of transmission field analysis in indoor channel modeling.

Joint Temporal and Spatial Sensing Based Cooperative Cognitive Networks

A joint temporal and spatial sensing based cooperative communication scheme is proposed, in which the cognitive users including source and relays share the spectrum with licensed (primary) user. The closed form expression of outage probability is obtained for the proposed scheme in Rayleigh fading environment. The outage probability of our proposed transmission scheme has been compared with schemes with pure temporal and pure spatial sensing.

Performance analysis of spectrum sharing mechanisms in cognitive radio networks

In this article, a non-preemptive (NP) mechanism is proposed to improve the quality-of-service (QoS) of secondary users (SUs) in joint leasing and sensing-based cognitive radio networks (CRNs). In this spectrum-sharing mechanism, a primary user (PU) could not forcibly terminate a SU with ongoing transmission. Both the typical preemptive and the proposed NP mechanisms are modeled by multi-dimensional Markov chains with three state variables. A decomposition-approximated method is used to derive the closed-form solutions of the steady-state probabilities in the Markov chains. The analytical results are verified by numerical results. System parameters that affect performance metrics are also investigated in these two mechanisms. The simulation results show that in the proposed mechanism the performance metrics of SUs such as force-termination probability and mean system delay are improved significantly, with an acceptable loss of PUs’ QoS in terms of mean waiting time and blocking probability. A QoS tradeoff can be achieved between the primary and the secondary systems. For QoS improvement of SUs, the proposed NP mechanism outperforms the preemptive mechanism in joint leasing and sensing-based CRNs.

Time Domain Transmission Coefficient for a Finitely Conducting Slab

The paper develops a simplified analytic solution for transmission coefficient of finitely conducting slab in time domain. To obtain the impulsive transmitting field, either for vertical or horizontal polarization, the relationship between the reflection and refraction on slab surfaces, as well as approximations to propagation loss is investigated. A numerical example of incident monocycle transmitting though a concrete slab using this technique is presented to illustrate the effective use of the method.