Equalization Techniaues - Essay Example

EQUALIZATION TECHNIQUES By Name Course Instructor Institution City/State Date Executive summary Wireless communication is one of the changes that has over the years grown tremendously to the extent of replacing conventional channels of communication which involved the use of cables. This has been made possible by exploitation and adopting the idea used to transmit radio frequencies. However, this has not been easy as this was a new concept being deployed and has led to various challenges in the wireless communication. One of the challenges facing wireless communication is inter-symbol interference, which refers to the collision of signal once they are transmitted. This collision leads to distortion of communication which sometimes leads to loss of vital information. Inter-symbol interference arises out of various reasons such as the reflection of signals by buildings. As a result of these, concerns have been raised as to ways in which inter-symbol interference could be reduced. This is because it is practically impossible to entirely eliminate inter-symbol interference. Minimizing inter-symbol interference became possible after the development of equalization techniques. Equalization techniques act interceptors between the sender and receivers thereby reducing inter-symbol interference. They achieve this by aligning the signal in the order, they are sent thus facilitating communication and exchange of other vital information. Therefore, equalization techniques have led to the enhancement of wireless communication. This is achieved by minimizing inter-symbol interference which have for a while hampered the development of wireless communication. Introduction Over the years communication has experienced drastic changes some of which were expected while others were not. Gone are the traditional communication channels that involved use of wired communication channels. With the tremendous technology advancement communication has now been laid in the wireless platform. Communication channels have exploited the existing radio frequencies and have applied such concepts to further communication. Nowadays people use mobile phones to communicate of which are based on the concept of wireless communication. Therefore, this means that communication between individuals is not limited unlike traditional methods where calls were made from designated places. In addition to these, wireless communication has led to the development of other platform, which incorporate wireless communication to achieve their objectives. One such development is the internet which is a form of wireless communication [1]. However, burdening of wireless communication can sometimes hinder communication between individuals. This can be attributed to conflicting signals arising from the different platforms using wireless communication as their preferred mode of communication. This has led to the development of numerous solutions to try and remedy this problem, but most of the proposed solutions have failed significantly. However, one of the most suitable solution to be developed is the use of equalization technique. Equalization technique refers to signal processing operations whose main aim is to reduce inter-symbol interference (ISI). Equalization techniques are classified into two categories; linear equalizers and non-linear equalizers. Linear equalizers are easy to implement, and are not to be applied where frequency fading takes place [2]. However, non-linear equalizers, on the other hand, are well suited to equalize wireless channel in cases where frequency fading takes place. Inter-symbol interference is described as an interference that is caused when two or more symbols collide or cross each other at one point. This collision affects communication leading to a noise effect at the end of the receiver. Therefore, developers came up with equalization technique, which has the capability to eliminate or minimize inter-symbol interference leading to better communication. It should also be noted that equalization techniques were not invented together with wireless communication, but rather they were developed much later to remedy problems of wireless communication. Therefore, this paper looks at inter-symbol interference and its effect on communication as whole. It tries to illustrate the various factor that could cause inter-symbol interference. In addition to these, the paper also looks at equalization techniques as ways of countering the effect of inter-symbol interference, thus enhancing communication. According to Kanthalue and Nanan [2] inter-symbol interference is a common aspect in the wireless concept, but it becomes a nuisance once it starts to affect communication. As earlier stated, inter-symbol interference refers to a situation where two symbols collide. This collision of symbols affects the communication as a whole since it leads to distortion of the symbols. Therefore, this means that at the receiver’s end symbols are not received as were transmitted, but rather they are received in a disorganized manner. This further makes communication difficult since signal received is distorted. This is mainly experienced with high bandwidth where massive data is being transmitted between sender and receiver. This can be attributed to the fact that the time between the signals decreases with an increase in bit rates. As a result of this, it then becomes exceedingly easy for two signals to collide leading to what is referred to inter-symbol interference. The presence of inter-symbol interference can also be attributed to the fact that channels exploiting radio frequencies do not have infinite bandwidth. Therefore, this increases the likelihood of collision of channels as they are being transmitted. According to Bottomley [1] present day communication is characterized by various factors that make it distinct from communication as was known earlier. This is witnessed in the adoption of the wireless concept to transmit signal thus enabling communication between without physical restriction. Wireless communication is a borrowed concept used in radio in the transmission of frequencies. The first development was the use of global system for mobile (GSM) which does not have many capabilities other than voice transmission. This was later followed by the introduction of enhanced data for global revolution (EDGE) which much like GSM was limited. However, it was faster that than GSM which meant that it had relatively high bandwidth and was affected by inter-symbol interference. However, with the introduction of 3G concept concerns were raised as to the quality of communication. This is because 3G integrates numerous activities, which compete for the same frequency something that could lead to conflicting signals. Therefore, this led to the need to incorporate equalization technique to try and counter the collision of symbols with an aim of improving communication. Implementation of the equalization technique would ensure that other activities supported by 3G platform function effectively. In addition to these, inter-symbol interference may also lead to loss of vital information, which could arise when two signals come together resulting to a distortion of the intended information. Previous modes of communication that incorporated the use of cables as a medium of transmitting information posed little challenges especially in relation to inter-symbol interference. This can be attributed to the fact that, with the use of cables, the transmitting environment for the signals is controlled thereby reducing the possibility of colliding symbols. However, with wireless communication this poses a great challenge because the environment is unstable. This could be attributed to the various variables which could enhance or play a role in the collision of symbols. One of these variables is multi path propagation which refers to the situation whereby signals reach the receiver using different paths. This can be attributed to the reflection of these signals caused by the presence of buildings. Therefore, this leads to collision of signals as they reach at the receiver’s end. This can be attributed to the delay in arrival of the signals arising out of reflection of the signal [2]. Therefore, with the introduction of wireless communication loss of information became a common thing which could be attributed to inter-symbol interference. Therefore, a need to try and eliminate or minimize inter-symbol interference grew over time. Some of the solutions developed performed poorly in that they were unable to minimize inter symbol interference. However, the development of equalization technique has made it a possibility to reduce inter-symbol interference. This is because most equalization techniques group the signals once they are sent, thereby reducing the probability of the signals colliding. There are various equalization techniques with each technique having a different approach in combating inter-symbol interference. However the most common technique is the adaptive equalization technique which makes equalization a possibility by tracking and training signals. Adaptive equalizers are usually placed at the IF of the receiver or at the baseband. This is because signals are stronger at the baseband of at the IF of the receiver, making equalization of signals easier and faster [3]. Tracking of signals entails a situation where signals of unknown channel are collected by the equalizer and grouped together depending on the source of the signal. This is made possible by the various unique variables that are present in every signal; therefore, this makes it easier to distinguish the various signals that are being transmitted through the radio channel. Once the radio channels are grouped it then becomes easier to minimize inter-symbol interference since. After tracking of the frequencies, the next stage is the training stage, which is responsible for guiding the signals. This ensures that signals correspond to the order in which they have been sent. Therefore, by combining both tracking and training it becomes possible for the equalization technique to remove the possibility of symbols colliding with each other thus ensuring that communication is uninterrupted [4]. The other technique that is normally used to remedy inter-symbol interference is the blind equalization technique. Blind technique differs from other equalization techniques by virtue that it is not supervised. This is because blind equalizations infers estimates of the signal statistics found at the receivers end to equalize a wireless channel. This ability is what has led to this technique being referred to as blind. However, for blind equalization to be effective it incorporates other factors such as the Bussgang algorithms. The Bussgang theory states that where the input of a nonlinear system is zero it should correspond to the output. This means that the output should be similar or almost similar to the input in order to facilitate equalization [5]. However, despite all the efforts put in place to facilitate wireless communication their various challenges that limit the application of equalization techniques. One of the factor that hinders the use of equalization techniques is the ever changing technology. Technology as is well known is not static but rather dynamic meaning that it changes from time to time. These changes bring about factors that were not anticipated thus hindering equalization techniques. In line with this statement present day, equalization techniques have been developed to deal with the factors that affect communication presently. A good example is the development of 4G network, which are supposed to possess very high bandwidths. As earlier stated high bandwidths are one of the causes of inter-symbol interference, and this could pose great challenges to the already established equalization techniques. Therefore, any development that was not put into consideration when developing equalization techniques makes it impossible for equalization techniques to handle [4]. Conclusion In conclusion, wireless communication has widely been accepted in almost every region and has proven to be very effective when it comes to communication. However, the use of wireless communication has come across various challenges, which have made its application difficult. This can be attributed to the numerous variables contained in the environment used to transmit wireless signals. Inter-symbol interference in wireless communication is probably one of the few and main factors that hinder wireless communication. Inter-symbol interference leads to distortion of symbols or signals used for transmitting information between the sender and receiver. These distortions in the signals affect communication as a whole since some of the vital information carried by the signal may be lost. However, in an attempt to make wireless communication more effective various equalization techniques have been developed. These main objectives of these equalization techniques are to ensure that signals are transmitted with minimal interference. This is achieved by minimizing the inter-symbol interference, thereby leading to an effective wireless communication. However, as much as equalization technique are of great significance to wireless communication they are faced with challenges. These challenges hamper the progress made by equalization techniques in ensuring that wireless communication is efficient and effective. Therefore, equalization techniques have played a major role in ensuring the wireless communication is protected. References [1] G.E. Bottomley, Channel Equalization for Wireless Communications: From Concepts to Detailed Mathematics, New Jersey: John Wiley & Sons, 2012. [2] S. Kanthalue, and P. Nanan, Pre- and Post- Equalization Technique Combining for Wireless Communications, ICOIN, pp. 336 – 340, Jan. 2013. [3] M. Enescu, M. Sirbu, and V. Koivunen, Adaptive equalization of time-varying MIMO channels, Signal Processing, vol. 85, pp. 81–93, Sep. 2005. [4] F.R.P. Cavalcanti, and S. Andersson, Optimizing Wireless Communication Systems, Berlin: Springer, 2009. [5] P.A. Regalia, and M. Mboup, Properties of Some Blind Equalization Criteria in Noisy Multiuser Environments, IEEE TRANSACTIONS ON SIGNAL PROCESSING, vol. 49, no. 12, pp. 3112-3122, Dec. 2001. Read More

Therefore, developers came up with equalization technique, which has the capability to eliminate or minimize inter-symbol interference leading to better communication. It should also be noted that equalization techniques were not invented together with wireless communication, but rather they were developed much later to remedy problems of wireless communication. Therefore, this paper looks at inter-symbol interference and its effect on communication as whole. It tries to illustrate the various factor that could cause inter-symbol interference.

In addition to these, the paper also looks at equalization techniques as ways of countering the effect of inter-symbol interference, thus enhancing communication. According to Kanthalue and Nanan [2] inter-symbol interference is a common aspect in the wireless concept, but it becomes a nuisance once it starts to affect communication. As earlier stated, inter-symbol interference refers to a situation where two symbols collide. This collision of symbols affects the communication as a whole since it leads to distortion of the symbols.

Therefore, this means that at the receiver’s end symbols are not received as were transmitted, but rather they are received in a disorganized manner. This further makes communication difficult since signal received is distorted. This is mainly experienced with high bandwidth where massive data is being transmitted between sender and receiver. This can be attributed to the fact that the time between the signals decreases with an increase in bit rates. As a result of this, it then becomes exceedingly easy for two signals to collide leading to what is referred to inter-symbol interference.

The presence of inter-symbol interference can also be attributed to the fact that channels exploiting radio frequencies do not have infinite bandwidth. Therefore, this increases the likelihood of collision of channels as they are being transmitted. According to Bottomley [1] present day communication is characterized by various factors that make it distinct from communication as was known earlier. This is witnessed in the adoption of the wireless concept to transmit signal thus enabling communication between without physical restriction.

Wireless communication is a borrowed concept used in radio in the transmission of frequencies. The first development was the use of global system for mobile (GSM) which does not have many capabilities other than voice transmission. This was later followed by the introduction of enhanced data for global revolution (EDGE) which much like GSM was limited. However, it was faster that than GSM which meant that it had relatively high bandwidth and was affected by inter-symbol interference. However, with the introduction of 3G concept concerns were raised as to the quality of communication.

This is because 3G integrates numerous activities, which compete for the same frequency something that could lead to conflicting signals. Therefore, this led to the need to incorporate equalization technique to try and counter the collision of symbols with an aim of improving communication. Implementation of the equalization technique would ensure that other activities supported by 3G platform function effectively. In addition to these, inter-symbol interference may also lead to loss of vital information, which could arise when two signals come together resulting to a distortion of the intended information.

Previous modes of communication that incorporated the use of cables as a medium of transmitting information posed little challenges especially in relation to inter-symbol interference. This can be attributed to the fact that, with the use of cables, the transmitting environment for the signals is controlled thereby reducing the possibility of colliding symbols. However, with wireless communication this poses a great challenge because the environment is unstable. This could be attributed to the various variables which could enhance or play a role in the collision of symbols.

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