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Essay On Wireless Communication

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Introduction
Wireless communication has improved dramatically in the last few years. Their networks are indispensable providing the means for mobility, city-wide Internet connectivity, distributed sensing and outdoor computing [10]. It allows the transfer of messages between people that are on the other side of the world. Without wireless communications people would not have a lot of the devices many 21st century citizens could not live without, namely the smartphone. It is also required for devices using Bluetooth, remote controls, Wi-Fi; really any electrical devices that communicate via a wireless or wired channel [1]. The popularity of communication systems is seen from nearly anywhere in cellular networks, wireless local area networks
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Today there are more than 7 billion mobile phone subscriptions, an increase of about 97% since the turn of the millennia whilst there are 3.2 billion people that currently use the internet. However, in the least developed countries only 89 out of the 940 million use the internet. This is only a 9.5% penetration rate which when compared to a developed country which average at a penetration rate of 82.2% seems quite ludicrous [2]. Almost 60% of the Internet traffic is generated by peer-to-peer applications where, typically, large files, such as movies and software distributions, need to be distributed from one or very few servers to a large number of users [1]. These statistics inform us just how important the work in the field of wireless communications is. Work will continue so that the less fortunate have more of a chance to get access to things like cellular networks and the internet. This will put pressure on maintaining the excellence of wireless communications in terms of rate, spectral efficiency and power consumption. An attempt is made also to keep the data transmission system as fast and reliable as possible. All of this has motivated researchers to integrate various wireless platforms such as cellular networks, WLANS and also, MANETs which is a mobile ad hoc network which continuously is a self-configuring, infrastructure-less…show more content…
These are amplify-and-forward, decode-and-forward and compress-and-forward.
The amplify-and-forward (AF) is the most simple and quickest of the three. It acts as an analogue repeater and was introduced in 2004. Whenever this type of relaying receives a signal all that it does is amplify the received signal from the source and transmit it to the destination. The destination receives two independently faded versions of the information so that it is able to make better decisions. Obviously errors will occur using this strategy. No encoding or decoding takes place here and the noise gained by the signal from the source to the relay will also be amplified!
The decode-and-forward (DF, may also be described as digital regenerative repeaters) strategy decodes the message received at the relay. It performs very well here but when it does fail to decode properly, an error propagation phenomenon is observed. To counter this methods have been introduced where the relay detects and forwards the source information only is case of high instantaneous source-to-relay link signal-to-noise
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