A mobile user, whether he is travelling or at any location, may be logging into a
network either for a routine work or for a mission critical application and needs ubiquitous accessibility to the multiprotocol-based networks. This requires a huge database, high speed real-time computation and extremely robust hardware and software supported infrastructure. New evolving networks bring RFID, WSN, NFC, bluetooth, Wi-Fi direct, wireless gigabit and many more emerging technologies under a uniform interfacing platform with a simpler user interface. Obviously, these capabilities can be met by improving the spectral efficiency of the available spectrum by implementing the link improvement techniques and also designing some compact VLSI circuits at low power dissipation.

This issue contains six papers, and out of these, the first one discusses the network capabilities and the next two are related to wireless link improvement techniques used in networks. The last two papers focus on the enhancement of the wireless system connectivity by discussing the design of a compact antenna and hardware circuits.

In high speed networks, the quality of service and reliability issues are very crucial, and to ensure optimal network performance, the network routing has to be efficiently handled. The network survivability after occurrence of failures has to be quickly restored to make a failure-prone network. The first paper, “A Comprehensive Survey on Routing Schemes for High Speed Networks“, by Veenu Pondwal and Himanshi Saini, presents a review, elaborating a comprehensive survey of the existing routing techniques in optical networks. Network performance is measured through various parameters such as Packet Delivery Ratio (PDR), link throughput, link bandwidth, delay and throughput.

Wireless communication performance is governed by the channel environment because the overall capacity of the serving technology is basically limited by the channel characteristics. Implementation of orthogonal space time coding to gain ultimate bandwidth efficiency at higher bitrate is an attractive choice to exploit the capability of Multi-Input Multi-Output (MIMO) system in wireless faded environment. The second paper, “Performance Analysis of MIMO Detection Schemes for M-Ary QAM Modulation“, by V K Chaubey, Girish Kakalwar and P C Hariprasad, presents a suitable mathematical model to evaluate the performance of a Zero Forcing (ZF) and Singular Value Decomposition (SVD) scheme receivers under MIMO structures. The analysis of the paper predicts that the performance of the SVD receiver is better at low SNRs due to the availability of CSI at transmitter end.

The third paper, “A Comparison of Generalized Cross-Correlation Methods for Time Delay Estimation”, by Ritu and Sanjeev Kumar Dhull, presents a comparative analysis of weighting functions used in generalized cross-correlation for the time estimation along with their simulation results. The paper observes peak sharpening in the correlation function influenced by weight effect. The effect of varying SNR on the estimated time delay has also been simulated.
The authors, B Premalatha, M V S Prasad and M B R Murthy, in their paper, “Performance Testing of Composite Dielectric Patch Antenna“, present a design of a patch antenna using two different dielectric materials in substrate to operate at 2.5 GHz. The design has been simulated to evaluate its gain and bandwidth using HFSS simulator.

The modern communication systems need larger bandwidth and smaller dimensional antenna. The fifth paper, “Design and Analysis of High Gain Proximity Feed Microstrip Patch Antenna for Wi-Fi Applications“, by Y Pandu Rangaiah and R V S Satyanarayana, deals with the design aspects of square microstrip patch antenna with proximity feed. The simulation study has been done for the proposed structure to see its utility for Wi-Fi and bluetooth applications. The designed antenna exhibits maximum gain of 7 dBi and return loss of –40 dB at center frequency of 5 GHz.

New generation telecommunication standards need reasonably high speed Digital Signal Processor (DSP) processors and circuits in the mobile devices embedded with compact power efficient digital logic blocks. Such digital systems process the multifaceted information code and therefore need code conversion operations. The paper, “A Survey of Various Reversible Binary to Gray Code Converters“, by P Gowthami, presents a survey on the various reversible binary to gray code converters.

--V K Chaubey
Consulting Editor