In addition to the frequency hopped and direct sequence, spread spectrum multiple access technique, there are certain other hybrid combinations that provide the advantage in the area of cellular mobile communication system. The available wideband spectrum is divided in to a number of subspectras with smaller bandwidth. Frequency Hopped Multiple Access Technique (FHMAT) consists of a direct sequence modulated signal whose center frequency is made to hop periodically in a pseudorandom fashion. In this paper we provide a Hybrid Spread Spectrum Techniques using Time Division Code Division Multiple Access (TDCDMA) system in which different spreading codes are assigned to different cell within each cell, only one user per cell is allotted a particular time slot. Time Division Frequency Hopping Multiple Access (TDFHMA) Technique has an advantage in severe multipath or when severe co-channel interference occurs. The subscriber can hop to new frequency at the subscriber can hope to new frequency at the start of a new time division multiple access frame. These different areas covered by the antenna beam may be served by the same frequency or difference frequency.
Keywords: Frequency Hopped Multiple Access, Time Division Code Division Multiple Access, Time Division Frequency Hopping, Space Division Multiple Access
1 Introduction
Spread spectrum techniques spread information over a very large bandwidth specifically, a bandwidth that is much larger than the inverse of the data rate. In this paper we are discussing various ways of providing multiple access by spreading the spectrum. We start out with the conceptually simplest approach, Frequency Hopping (FH). We then proceed to the most popular form of spread spectrum, Direct Sequence-Code D...
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... Hybrid Wireless Networks Using Autonomic Computing Principles” IEEE, CNSR, 2005
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Enclosed is a rough high-level conceptual view of the communication channels. This is very preliminary as we don't what suitable devices we can use for multiplexers, demux, and converters. The idea is to design a full-duplex serial com link between point A and B. The bandwidth is limited in the copper wiring (telephone line) probably would not go any higher than 115 kbps using a modem a constraint distance of 5 miles.
L. Ophir "802.11 Over Coax - A Hybrid Coax - Wireless Home Network Using 802.11Technology", Consumer Communications and Networking Conference, pp.13 -18
6) Michele Zorzi, “Wireless Sensor and networks: Recent trends and Research Issues’’, University of Padova, Italy, IEEE communication society, Poland, April 28-30, 2008.
Cellular phones are a phenomenon that has engulfed people in the nineties. They have become a common occurrence whether you are waiting in line at the super market or in a movie theatre. One professor at Murray State University said, “Many students are carrying them, I had a student get a call in the middle of a test last semester.” Although many people have accepted the thought of carrying a telephone wherever they go, others have not taken the onslaught of cell phones quite so easily. Cell phones have become part of everyday life, and with the dramatic changes that have been made, there is no sign of their existence diminishing. Today, cellular service is available in all 306 Metropolitan Statistical Areas across the country and all of the 428 Rural Service Areas.
Modulation is a process of changing the characteristics of a radio wave to encode an information signal and sending that information to the other end. Readers send a continuous radio wave and the tags modulate this base band signal by adding encoded information into it, which the readers decode. Modulation schemes used for RF communication are amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK). The modulation technique’s choice is based on the power consumption, reliability and available bandwidth. ASK is most commonly used in load modulation and PSK for backscattering.
.... A. (2012). LTE, LTE-advanced, and WiMAX: Towards IMT-advanced networks. Chichester, West Sussex, U.K: Wiley.
The uses of Digital Signal Processing in communications has become so large scale that nearly any form of analog communication is considered obsolete. Today, nearly any form of communication used, aside from verbal communication, relates to Digital Signal Processing. Some of the more prominent uses for DSP in communications are; local area networks, cell pho...
Introduction: With the advancement in technologies, concentrating on transceivers is increasing. Transceivers operate at various frequencies. The author uses Wilkinson power divider (using three section transmission line transformer) which operates at three different arbitrary frequencies simultaneously to generate the required specifications. This condition of using three different frequencies on contrary to using dual frequencies makes this /or made this paper publishable. This circuit operates in the frequency range 900 MHz - 2.3 GHz.
Print. The. Gordon A. Gow, and Richard K. Smith. Mobile and wireless communications: an introduction, McGraw-Hill International, 2006. Print.
‘‘If I have seen farther, it is by standing on the shoulders of giants.’’ is very truly coated by Sir Isaac Newton. Ideas gave way to idea. When Marconi invented wireless communication 100 years ago, we had no idea that one day life will seem to be impossible without it. It has penetrated each and every aspect of human life and has resulted into endless demands on bandwidth and spectrum. And by standing on the shoulders of giants, Teletarand Foschinigave the technique of MIMO system which would increase the spectral efficiency of the wireless system to its maximum compared to all the current technologies. Multiple antennas are used for transmission and reception to increases the capacity of the wireless channel.Capacity is expressed as the maximum achievable data rate for an arbitrarily low probabilityof error. Thistechnology received a fillip when TarokhEtA introduced their space-timetrellis coding techniques and Alamouti introduced his space-time block codingtechniques to improve link-level performance based on diversity. Another boost came in form of BLAST Technology. But in this paper, our focus will lie basically on the MIMO wireless channel and how to determine its capacityunder different conditions. And space-time blocks coding techniques. We will discuss the benefits of the topic discussed and future prospects to enhance the usage of limited available spectrum.
This report will describe the two forms of data communications in terms of the physical interfaces and modes of operation. It will describe the features of data communications equipment in relation to synchronous and asynchronous communication including modems, network terminating units and sending and receiving equipment.
People in the present society have turned from the use of the old means of communication to the more advanced and technological ways of communicating. Technology has made it easier for people to communicate in a faster, efficient, and cost saving means through the introduction of the communication channels. The world has turned out to be the centre for technology with different technologies emerging daily as the people continue to develop from time to time to cope with the growing technology. The benefits of adopting the communication technology are explained in this article which shows why people do not function without technology.
Ham radios are the communication tools used by a large number of people across the world to connect with their friends. Ham radios are used universally for communication purposes; however, despite being outdated, these radios have still not lost their essence. Therefore, in order to provide a manual regarding its use, this book, Ham Radio Guide: Quick Start Ham Radio Guide- from Beginner to advanced, has been written.
My mobile phone network coverage allows me to make a call wherever I want, and the call is never cut off by the network. Independent surveys show that it has the best signal quality with excellent call clarity. The network covers 99 percent of the population, and it has installed more transmitters than any other digital network company. They guarantee that they work the best; in fact, they will even add a free minute of talk time if the call is ever lost. International and off-peak calls are the cheapest in the area. The company has been voted number 1 in customer satisfaction for 5 years in a row.