Modern analog and digital communication systems development using GNU Radio with USRP

In this modern world many communication devices are highly intelligent and interconnected between each other. Any up-gradation of the hardware in the existing communication devices is not easier one. Compatibility of the new hardware with existing hardware is highly essential. But the new protocols may or may not support the older one. The solution for these problems can be provided by using the reconfigurable hardware design. The hardware can be reprogrammed according to the new change in technology up-gradation. The cost of commercially available hardware and software requirements for setting up such a module is very high. This can be solved by using Open source hardware and software such as Universal Software Radio Peripheral (USRP) and GNU Radio. This work demonstrates how the modern analog communication system like Community Radio Schemes and Radio Data System (RDS) and digital communication systems such as Simple Digital Video Broadcasting (DVB) and OFDM based data communication can be developed using the Open source hardware USRP1. This work will be helpful even for first year level of engineering students to easily implement any communication and control applications with cheaper cost.     

基于PLC与变频器的空压机恒压供气系统

本文介绍了一种基于PLC与变频器的空压机恒压供气系统的工作原理与构成。系统中高压变频器采用一拖二方式,控制一台活塞式空压机的转速,以保持整个系统的恒压供气。另外由于系统涉及到不同PLC以及PLC与其它设备之间的通讯,通过采用不同通讯协议构建了一个通讯网络。以某矿为例,我们介绍了系统的具体实现。     

A generic multicast transport service to support disconnected operation

Many mobile computing applications can profit from process groups and reliable multicast communication to maintain replicated data, but most operating systems available today fail in providing the primitive operations needed by such applications. In this paper we describe a highly configurable, Generic Multicast Transport Service (GTS), which supports the implementation of group-based applications in wide-area settings. GTS is unique in that it offers fault-tolerant, order-preserving multicast on arbitrary communication protocols, including e-mail. As another distinguishing mark, messages can be sent to processes even when they are temporarily unavailable, which permits disconnected operation and mobility. We further propose an object-oriented system design consisting ofadaptor objects interconnected to form aprotocol tree. Adaptor objects offer a common interface to dissimilar communication protocols, and make it easy to incorporate new protocols into GTS. Currently, GTS is being used in a cooperative software engineering environment and in other projects. GTS is available for anonymous ftp.Research supported by grants from Siemens-Nixdorf, Union Bank of Switzerland, and KWF/CERS     

Protocol selection and interface generation for HW-SW codesign

The aim of this paper is to present a communication synthesis approach stated as an allocation problem. In the proposed approach, communication synthesis allows to transform a system composed of processes that communicate via high-level primitives through abstract channels into a set of processes executed by interconnected processors that communicate via signals and share communication control. The proposed communication synthesis approach deals with both protocol selection and interface generation and is based on binding/allocation of communication units. This approach allows a wide design space exploration through automatic selection of communication protocols. We present a new algorithm that performs binding/allocation of communication units. This algorithm makes use of a cost function to evaluate different allocation alternatives. We illustrate through an example the usefulness of the algorithm for allocating automatically different protocols within the same application system     

A fieldbus prototype for educational purposes

One of the problems with instrumentation systems is the interconnection between the multiple devices with different communication protocols. Exacerbating this problem are two typical requirements of interconnection: minimize cabling cost and avoid degradation of the signal during transmission. Cabling cost can be reduced through several multidrop communication systems: industrial local area networks or wireless communication. Reduction of signal to noise can restrict system performance and the quality of manufactured products, even if high-accuracy devices are used. Another problem in the field of manufacturing instrumentation networks is that industry uses multiple solutions to interconnect instrumentation with different communication protocols. This article presents the development of a prototype for an instrumentation network with the goal to study and analyze the characteristics of the different communication solutions. The overall system contains a large number of instrumentation devices, which is a great advantage for educational purposes and laboratory experiments. The students can configure, calibrate, and operate a large number of instruments connected to different segments of the DCS. We also connected some current-loop devices to the FF system to evaluate their performance when connected to a fully digital network. Results from the prototype DCS show that networking between different instrumentation devices and protocols can be successful and that a hybrid solution using conventional 4-20 mA current loop and fully digital instrumentation can work to leverage existing analogue systems. Future work will include the development of a fieldbus network analyzer to trace messages in the network and study the quality of FF service parameters, such as packet loss and delay measurement, as a function of network load.     

ENUM — Phone numbers on the Internet

The problem of a single identifier for multiple communication services can be solved with different approaches. One simple approach is the ENUM system developed by the IETF (Internet Engineering Task Force), using existing E. 164 telephone numbers, protocols and infrastructure to point to different services available under this identifier. The technical aspects of the underlying protocols and the administrative aspects of the distributed database used — the domain name system — are presented. This includes the related activities in ITU and ETSI and possible national implementations.     

Die Firewall-Problematik bei Voice over IP

The basic principle of the Internet is to connect intelligent terminals via a relatively simple network made up of routers. This principle was broken by the introduction of so called middleboxes, e.g. firewalls. These network elements, mostly interconnected between clients and servers for security reasons, lead to many problems in the Voice over IP-telephony. Using additional protocols that control the middleboxes, these problems can be solved. UPnP and MIDCOM are two of the most important approaches. This article compares the two protocols and shows their potential in connection with VoIP.     

MIMO-OFDM系统速率自适应传输方案

在采用TDD工作方式的MIMO-OFDM实际通信系统中,由于收发两端环境的不同导致干扰对称的假设不再满足。为了弥补这一影响,准确地确定系统的最佳传输参数,提出了一种基于事件驱动机制的闭环自适应传输方案。该方案通过在收发双方建立一条闭环控制信息传输链路,实现了迅速准确地确定最佳传输参数的目的。实验仿真结果表明,当在MIMO-OFDM系统中采用该方案时,可以有效提高系统的吞吐量,减小系统的中断概率。     

基于C8051F040的以太网-CAN转换电路设计

以太网和CAN总线应用广泛,但由于其通信协议不同,两种总线器件间无法进行数据通信,因此,设计了基于CP2200与C8051F040的以太网总线与CAN总线接口转换电路,并给出部分相关硬件电路与软件设计分析。在保证数据完整和协议可靠的前提下,通过握手协议和简化的以太网协议,不仅实现了以太网数据与CAN数据的转发,同时还顺利的解决了以太网的高速性与CAN的低速率冲突,以及两者数据包之间的大小不同的矛盾。     

Cognitive Wireless Communication Networks (Hossian, E. and Bhargava, V.; 2007) [Book Review]

?Cognitive radio? is emerging as a promising technology to cope with the spectrum scarcity as well as the spectrum underutilization problem in the next generation wireless communications systems. This book, Cognitive Wireless Communication Networks, edited by Ekram Hossain and Vijay Bhargava, puts together a rich set of research articles featuring recent advances in theory, design, and analysis of cognitive wireless communication networks. The book consists of 15 invited articles from distinguished researchers in this area, which cover a wide range of topics related to the cognitive radio technology. In particular, the topics covered in this book include fundamental challenges and issues in designing cognitive radio systems, information-theoretic analysis of cognitive radio systems, spectrum sensing and co-existence issues, adaptive physical layer protocols and link adaptation techniques for cognitive radio, orthogonal frequency division multiple access (OFDM) and ultra wide band (UWB)- based cognitive radio, different techniques for spectrum access by distributed cognitive radio, cognitive medium access control (MAC) protocols, decentralized learning-based dynamic spectrum access methods, and microeconomic models for spectrum management in cognitive radio.     

Analysis of energy consumption for multiple object identification system with active RFID tags

Radio frequency identification (RFID) systems are very effective for identifying objects. Existing published works focus on designing efficient collision resolution protocols for the tag identification problem in RFID systems with passive RFID tags. However, advances in low‐cost and low‐power sensing technologies will make active RFID tags more popular and affordable in the near future. In multiple object identification systems with active tags, the tags are designed for extremely low‐cost large‐scale applications such that battery replacement is not feasible. This imposes a critical energy‐constraint on the communication protocols used in these systems. In this paper, we analyze energy consumption and identification times for several protocols. The objective is to decrease energy consumption of tags by reducing both the total identification time and the total active time. Copyright © 2007 John Wiley & Sons, Ltd.     

Computer-aided design and evaluation of mobile radio local areanetworks in RTI/IVHS environments

An approach to designing and evaluating protocols for a class of mobile radio networks is presented. Characteristics of these mobile radio LANs are described, derived from the background of road transport informatics/intelligent vehicle highway system (RTI/IVHS) applications. Performance measures defined as suitable for the requirements of multipoint intervehicle communication are based on the concept of the zone of relevance, an area around a vehicle where communication to relevant neighbors is required. The simulation environment MONET3 has been designed to evaluate these measures. Protocol design in MONET3 requires an exact model of propagation characteristics and a realistic model of road traffic. A measurement-based 60-GHz channel model developed for intervehicle communication is presented. MONET3 is interconnected to a dedicated traffic simulator, the Autobahn Simulator, originally designed for traffic engineering in RTI systems. A case study using the simulator is presented as an example     

The Navy's Use of Digital Radio

Since the early 1960's, the Navy has utilized digital data links in support of their Tactical Communication, Command and Control Systems. Most of these systems continue to be used operationally. They include links 4, 11, and 14. These systems, however, lack the ability of combatting the anticipated electronic warfare threat as well as providing the performance required of a modern digital data system. Two new systems are in development that will improve performance as well as meet future threats. They are Fleet Satellite Communications and the Joint Tactical Information Distribution System. The demand of implementing new systems while retaining backward compatibility has suggested using an integrated architecture for the aircraft's communication system. The Tactical Information Exchange System is a communication's system design utilizing programmable multifunction signal processing components interconnected with a BUS architecture that may be the ultimate solution to the Military aircraft communication design problem.     

Random access protocols for high-speed interprocessor communicationbased on an optical passive star topology

A multiple-instruction multiple-data (MIMD) distributed memory parallel computer system environment is considered. Media access control protocols that maintain good performance with high capacity optical channels are investigated. Three examples of star-coupled structures are introduced, one of which exhibits optical self-routing. Self-routing single-step optically interconnected communication structures can be designed through the incorporation of agile laser diode sources and wavelength tunable optical filters in a wavelength-division multiple-access environment. Intermediary latencies typical of MIMD distributed memory systems are eliminated. The degree and diameter of the resulting structures are dramatically reduced, and the complexity of the communication subsystem is reduced since intermediate buffering and routing of packets are eliminated     

Automated repair of complex systems by fault compensation

A formal method used to repair discrete-event systems consisting of communicating processes is described. Two mechanisms of repairing faulty systems are proposed: the first inserts a new “compensator module” into the communication channel between the faulty process and one or more of its neighbors; the second modifies a neighbor of the faulty process in a compensating manner. The two mechanisms fall under a class of methods in which faults are not fixed by replacement of a faulty unit with a fault-free one, but where changes to the non-faulty parts of the system repair the system. A finite-state model is used to describe processes, and the problem is solved for two models of communication: the symmetric (or the handshake) model and, an asymmetric model. The algorithm is described, and examples are presented, including an indication of how the approach may be applied as part of a sophisticated fault management system for communication networks     

波束成形在TD-LTE-A系统中的性能优化

TD-LTE系统中的波束成形(Beam Forming)会受到收、发天线不对称性的影响。TD-LTE-Advanced(TD-LTE-A)系统中使用上行多天线发送可以解决天线不对称性的问题,因此需要对其分析以优化Beam Forming的性能。通过对上行多天线的信道状态信息(CSI)做特征值(SVD)分解,指出了Beam Forming对下行信噪比(SNR)的改善。针对Beam Forming模式下SNR和链路质量指示(CQI)的差异,提出了一种优化链路自适应的方法。数值仿真验证了优化后的TD-LTE-A相比TD-LTE的Beam Forming吞吐率最大提高了24%,其结论对商用TD-LTE网升级到TD-LTE-A具有显著价值。     

Traffic-adaptive aggregate channel allocation for future cellular communication systems

A fundamental problem in third-generation mobile systems is the adaptation of the channel allocation to the traffic volume variation. Traffic adaptation may be partly achieved by the following (aggregate channel allocation) problem: given the set of channels, the cell structure and the load to be accommodated in each cell within a certain time zone, find the optimal allocation of channels to cells subject to the restrictions arising from the minimum permissible distance of cells where the same channel can be used at the same time. In this paper the problem is optimally formulated and efficiently solved by a heuristic. In the sequel the performance of a combined channel management scheme that uses the above problem for handling major traffic variations and a distributed DCA scheme for handling local traffic variations is assessed. Finally, results are presented and some concluding remarks are made. © 1998 John Wiley & Sons, Ltd.     

A power line communication network infrastructure for the smart home

Low voltage electrical wiring has largely been dismissed as too noisy and unpredictable to support high-speed communication signals. Advances in communication and modulation methodologies as well as in adaptive digital signal processing and error detection and correction have spawned novel protocols capable of supporting power line communication networks at speeds comparable to wired LANs. We motivate the use of power line LANs as a basic infrastructure for building integrated smart homes, wherein information appliances ranging from simple control or monitoring devices to multimedia entertainment systems are seamlessly interconnected by the very wires that provide them electricity. By simulation and actual measurements using "reference design" prototype commercial powerline products, we show that the HomePlug MAC and PHY layers can guarantee QoS for real-time communications, supporting delay-sensitive data streams for smart home applications.     

Transmission of group 3 facsimile over inmarsat maritime digital satellite mobile channels

The importance of facsimile communication over public telephone networks is evidenced by the rapid growth in the number of Group 3 facsimile end-user terminals. In this paper the main characteristics of a real-time bit-rate reducing approach are described whereby facsimile signals are demodulated and their associated protocols converted by a facsimile interface unit (FIU) to a format suitable for transmission over Inmarsat-B maritime digital satellite channels. The FIU concept was developed to allow ‘off-the-shelf’ facsimile terminals to be interconnected via the PSTN through Inmarsat's satellite networks and to permit the provision of enhanced user services by converting Group 3 facsimile protocols to broadcast operation. In addition, the FIU concept is designed to compensate for the longer access and transport link delays encountered in mobile satellite systems, and to permit facsimile call recovery procedures to be successfully concatenated with satellite channel error detection mechanisms.