自由空间基于激光编码调制技术语音通讯机的系统设计

基于自由空间光通讯(FSO)技术和OCDMA编码调制技术实现了自由空间语音异地通讯,具有高速高效、抗干扰能力强、保密性好等优点。系统设计采用双CPU结构,主控CPU单元主要实现语音采集、信号编码、数字调制等功能,辅单片机则为FSO关键技术ATP伺服系统的控制核心,论述了设计要点,并给出了测试结果。     

Concepts of Simultaneous Use in Mobile and Wireless Communications

Wireless communication research is evolving towards integration, inter-working and convergence of wireless systems, which will lead to several concepts of simultaneous use. In the present paper, a coherent set of 10 concepts of simultaneous use is identified, and structured into a space of simultaneous use, where services, systems and operators act as building components. A high level analysis is performed, where the pros and cons of the different concepts are identified. Illustrative examples are also provided for some concepts. Several parameters are listed for the evaluation and comparison of simultaneous use concepts (e.g., cost, throughput and complexity), depending on taking either a users or an operators perspective. One of the largest benefits of this systematic identification of simultaneous use concepts is the identification, from the perspective of users and operators, of essential R&D issues on inter-working and integration, which will lead to a promising pervasive wireless communications future.     

Method of state code matrixes in the realization of optical switching using Perfect Shuffle

Based on the Left Perfect Shuffle (LPS) optical communication network constructed by cascade multi-stage LPS interconnection, using Looping algorithm, any arbitrary sequence of the input signals can be realized. However, instead of obtaining the simultaneous state codes of the same level node switches through mathematical analytical expressions directly, only routing tags of each channel can be obtained through mathematical analytical expressions so as to draw out topological chart of the network to obtain the state codes implied in the chart. Thus, the states of the switches cannot be directly programmed and controlled by computer in practical application. In this paper, based on the Looping algorithm, a method of stage code matrixes is presented to resolve this problem. By using the method, the simultaneous state codes of the same level’s four node switches can be directly obtained, which is convenient for the computer to provide controlled signals needed to finish the permutation for each node switch. The method of stage code matrixes provides further theoretical basis for the realization of optical switching by integration of Perfect Shuffle and high-speed optical switches.     

一种新型的突发汇聚算法研究

分析了现有的突发汇聚算法,同时针对现有汇聚算法的一些特点,提出了一种新型突发包汇聚算法,可以实现在不同网络负载的情况下,根据到达边缘节点的速率同时结合网络的性能(丢包率),动态的调整突发包汇聚的门限值,从而实现了智能组包,克服了原有算法简单,不灵活的缺点.通过仿真结果可以得知,该算法可以明显改善光突发交换网络的丢包率和时延性能,能够很好地支持实时性要求很高的数据业务.     

Investigation of multiwavelength clock recovery based on heterodyne beats of sideband-filtered signal

We investigate a new parallel all-optical clock recovery scheme based on heterodyne beats of an optical sideband-filtered signal. The oscillating clock signal is recovered when the filtered sideband is combined with a stable local oscillator. The filtering is performed with an optical resonator, which by nature provides possibility for multiwavelength operation. The local oscillator could be realized by a multiwavelength laser, whose emission wavelengths are injection seeded with carrier wavelengths of the input data. The output signal of such a configuration benefits from a reduced bit-pattern effect and a stable offset level. The sideband filtering is demonstrated for 23 simultaneous channels at 100 GHz DWDM grid, each hosting a data stream of 10 Gbit/s.     

Propagation characteristics of tilted partially coherent rectangular flat-topped beam in turbulent atmosphere

In this paper, the effects of atmospheric turbulence on the intensity distribution of a tilted Rectangular Partially Coherent Flat-Topped (RPCFT) beam were studied. An analytical formula for the intensity distribution was derived. POWER In Bucket (PIB) value is calculated numerically. The effects of source parameters – such as correlation length, order of flatness and tilt coefficient – on the intensity were analyzed. Detailed analysis demonstrates that these parameters have an influence on beam propagation properties. The analyses are illustrated by numerical examples and graphs.