Thursday, October 3, 2019
Enhancing IEEE 802.11 Wireless Networks Essay Example for Free
Enhancing IEEE 802.11 Wireless Networks Essay Abstract            The IEEE 802.11 standard for wireless network is a very important standard especially today that wireless technologies are very popular due to its effectiveness and usefulness. However, the standard supports the use of omni-directional antenna which radiates and receives signals in all directions that does not support spatial reuse and does not have high capacity and gain. Research studies show the benefits and advantages of using directional antennas instead of omni-directional antenna in wireless networks. Spatial reuse and high capacity are both very important especially today that the wireless networks are increasingly deployed due to the demand and needs of the users. But, as mentioned, IEEE 802.11 supports the utilisation of omni-directional antenna and not of directional antenna, thus to be able for directional antenna to be at its optimal use, the IEEE 802.11 protocols must be amended to be able to address problems associated with the use of directional antenna. Directional antenna or directivity of an antenna can be created using antenna elements that are combined to form an array. Smart antennas which are becoming popular today have achieved directivity due to the techniques employs with it. Introduction            Due to technological development in data and telecommunications during the past years, the Institute of Electrical and Electronics Engineers (IEEE) of the United States developed standards and guidelines to ensure orderly transfer of information between two or more data communication systems using different equipment with different needs. Standards and protocols are useful in ensuring that equipments such as computers, mobile phones, and communication devices from different manufacturers and providers have established compatibility and interoperability.            However, due to rapid technological development and introduction of newer technologies brought about by the increasing demands and needs of users, some standards are needed to be enhanced and improved. This is because as newer technologies are created, more and more data are needed to be transmitted requiring more capacity for the existing infrastructures. If standards and protocols are not improved, existing communication infrastructures will only have limited capacity causing serious problems such as interference and slow speed. People nowadays always demand for real-time communication of various data such as video, audio, pictures and multimedia. Background            One of the most innovative technologies today has been the wireless communication technology. Wireless technology encompasses the use of television and radio, mobile phones, wireless internet connection and computing system which are all very important for communication needs, eliminating the need for cables and wires and making possible the communication even in the remotest areas as along as there is available signal. WLANs increased the degree of mobility which are not possible using the conventional local area networks. In mobile phone communication alone, development has been tremendous that from analogue to GSM, now comes the 3G and 4G mobile systems. In the internet technology, connections have developed from ISDN to dial-up to DSL and now Wireless LAN which is very popular today. Communication between computers and mobile phones are also now possible with the GPRS technology.            These technologies are primarily intended for easy and real-time communication brought about by fast-paced lifestyle of people and also because of globalization. Mobile data and communications have become important for personal, professional, and business use. Because there are so many manufacturers and service providers from different locations, and also because of the popularity of these technologies, the IEEE developed the IEEE 802.11 which is a standard particularly intended for Wireless Local Area Networks. However, as WLAN experienced development and are improved, the IEEE 802.11 is also needed to be enhanced to be able for WLANs to be at their optimum performance. Additionally, because of the many uses and demands for WLAN, it has been increasing deployed causing interference between transmissions. Interference in data communications is a serious problem for it caused delay of transmission and alterations or distortion of signals that caused unreliable, unclear and error in messages received. The use of directional antenna is a well known method to reduce interference and to increase the range and capacity of wireless networks (Zhu et al, 2005). However, the IEEE 802.11 is not designed for the use of directional antennas. This project which is focused on the enhancement of the IEEE 802.11 using directional antennas and multiple receivers is important to be able to determine in-depth what improvement and advantages can directional antennas and multi-receivers can contribute to the current IEEE 802.11 Wireless Networks standard. Literature Review            This part of this proposal reviews literatures that describe the IEEE 802.11 WLAN standard in details to be able to determine the needs for the enhancement of the standard. The literature review also provides earlier research about the functions and advantages of directional antennas This review is a brief discussion providing an overview of the detailed review of literatures that will be provided in the chapters of the research study. 3.1. The IEEE 802.11 Wireless Network Standard            Aside from promoting interoperability, the IEEE 802.11 standard for wireless network was created to deliver services that were previously found only in wired networks but have been found out to be possible using wireless networks; to achieve high throughput; for highly reliable data delivery; and for continuous network connection (Ergen, 2002). As a standard, the IEEE 802.11 established the network architecture, components, type of equipments and set of services offered that must be complied with by wireless network administrators and providers. These are also known as the physical layer and that IEEE 802.11 WLAN standard provides a number of physical layer options in terms of data rates, modulation types and spreading spectrum techniques (Ergen, 2002). This means that the medium, the path that the signal transmitted and received via the WLAN, the range, location, frequency to be used and the type of antenna to be used are all determined by the IEEE 802.11 standard. IEEE 802.11 does not only specify the physical layer characteristics but also the link layer protocol for medium access in broadcast channels (Dham, 2003). The medium access control protocol is designed for the specified physical layer characteristics thus any changes made in the physical layer also requires significant alterations in the MAC protocol.            The MAC layer of the standard defines two different access modes: the Distributed Coordination Function (DCF) and the Point Coordination Function (PCF) (Xu Saadawi, 2003). DCF is a mechanism which is a Carrier Sense Multiple Access with Collision Avoidance. The standard allows the use of a basic access method or an optional handshake which is done by exchanging Request to Send (RTS) and Clear to Send (CTS) messages which are also the frame sent from the source to the destination and an acknowledgement from the destination that the frame was received correctly (Erger, 2005). These frames or control packets contain the proposed duration of data transmission while nodes or stations within the vicinity of communicating nodes overhear either of these control packets and suspend transmission for this proposed duration (Choudhury et al, 2002).            This process unable the nodes or devices to communicate directly with all other devices and for a wireless device to be able to transmit and receive at the same time thus the IEEE 802.11 MAC implements a network allocation vector (NAV) which is a value that indicates to a station the amount of time that remains before the medium becomes available (Erger, 2005). With this standard, directional antenna is obviously not utilised because in using directional antennas, it is possible to carry out multiple transmissions in the same neighbourhood provided that the beamwidth of the directional transmissions is not very large (Choudhury et al, 2002). 3.2. The Directional Antenna            An antenna is one or more electrical conductors of a specific length that transmits radio waves generated by a transmitter or that collects radio waves at the receiver (Frenzel, 1994). It is a basic component of every wireless networks, thus it must be chosen carefully depending on how it will be used. WLAN commonly used omni-directional antenna which allows for transmission and reception of messages in any direction (Frenzel, 1994) which is commonly used in wireless internet connections and wireless telecommunications. However, because the transmitted signal is exposed in any direction, interference with other signal has been a problem. In search for the solution with the problem of interference, various research (Dham, 2003; Zhu et al, 2005; Choudhury et al, 2002) have been focused on the use of directional antenna in WLANs.            The primary advantage of directional antenna is that it eliminates interference from other signals being received from all directions except the direction of the desired signal (Frenzel, 1994). It was found out that the use of directional antenna for transmission gives the highest capacity, allows spectrum reuse, and provides range extension (Zhu et al, 2005). At the receiver, the antenna is pointed directly at the station to be received thus rejecting signals from transmitters in all other directions (Frenzel, 1994).            Another advantage of directional antenna over omni-directional is that there is greater efficiency of power transmission while when omni-directional antenna is used at the transmitter side the transmitted power goes off in all directions wasting a significant amount of power (Frenzel, 1994). It is argued that all messages should be sent in directional mode to take advantage of this gain (Zhu et al, 2005). Choudhury et al (2002) conducted a study and proposed a protocol that exploits the benefits of using directional antenna namely spatial reuse and higher transmission range. On the other hand, the use of directional antenna also poses some problems such as higher collision probability. That is, as space is segmented and the carrier is reused with directional antennas, the amount of MAC information required for conflict-free transmission increases (Zhu et al, 2005). Because the current IEEE 802.11 standard does not support spatial reuse, several problems may occur when directional antennas are used without changing the modifying the existing protocol. Collision occurs due to the deafness of the nodes as these nodes are immersed in only one direction. And because of this deafness, the transmitting nodes will send RTS packets repeatedly which is a waste of bandwidth (Zhu et al, 2005). The research study conducted by Zhu et al (2005) focused on solving the problems caused by the spatial reuse which is higher collision probability and proposed a protocol called sectorised 802.11 MAC protocol. These two studies along with the other studies serve as the framework of this research. To create an antenna with directivity and gain, two or more antenna elements are combined to form what is known as an array (Frenzel, 1994). Antenna array has the capability of spatial signal separation and could radiate frequency energy towards a desired receiver with narrow beamwidth and null towards an interfering terminal to reduce the negative impact of multi-path and co-channel interference (Zhou, 2006). Phased array antenna systems are an example of an array. Phased array antennas consist of an array of antenna elements connected by a feeder or adder network arranged so that their individual signals combine to provide maximum gain in one direction while minimising it in other directions (Dham, 2003). There is also what is called smart antenna which is consist of multiple antenna elements arranged in a special configuration and connected through complex weights (Zhou, 2006). Smart antenna Switched beam and adaptive array antenna are the two major categories of smart antenna. Switched beam is the simplest smart antenna with a number of fixed beams in predetermined directions at the antenna site (Zhou, 2006). Adaptive array on the other hand uses a complex signal processing algorithm to continuously detect multi-path and interference among desired signal (Zhou, 2006). The studies about the applications of smart antennas in wireless networks are also related and will be useful in the completion of this research study. Zhou (2006) added that a smart antenna can be applied to all current major wireless protocols and industrial standards to achieve higher system capacity, larger network coverage and higher data rate thus smart antenna must be further investigated to determine what it can contribute to the enhancement of IEEE 802.11 with directional antennas. Aims and Objectives            In conducting any research, it is important that definite sets of objectives are present. These objectives will serve as the researcher’s guide in conducting the data gathering, data analysis and conclusion formulation. The primary objective of the research is to provide a protocol designed for the utilisation of directional antennas in wireless local area networks. Such protocol is proposed to be used in the deployment of WLAN using directional antennas thus it includes some amendments on the original standards, architecture, and physical layer. However, this general aim is an umbrella objective that would dictate the general path that the research will take. Within this umbrella objective are the specific aims of the research that will allow the researcher to touch the important aspects of the topic. These specific aims are the following: To identify the problems associated with the current protocols to determine the necessary adjustments or enhancement that are needed to be done; To determine the characteristics of directional antennas and what it can contribute to improve the capabilities of the wireless local area networks; To evaluate the advantages of having multiple receivers in wireless local area networks; To investigate on the differences of the current protocol and the proposed protocol and determine the limitations of the latter; and To test the effectiveness of the proposed standard. Intellectual Challenge            The most intellectual challenge on this research is the proposal itself. The IEEE 802.11 is developed by reliable engineers and to propose an enhancement for this standard is a big challenge thus the research study should be based on reliable data. The proposed protocol should also be tested on using a prototype and accurate calculations to ensure that the outcome of the studies is viable. Research Program 6.1 Research Methodology The method of collecting data for the dissertation will be composed of two methodologies. The first methodology is review of related literature or secondary sources. Reviewing earlier studies and other related literature would allow the researcher to become familiar with the already accepted theories and statements pertaining to the topic. The sources should be from technical books, journals, earlier theses and published articles technical organisations such as the IEEE. The second methodology would be surveys and personal interviews. Technical professionals like engineers and technicians from different communication network companies and Internet service providers (ISP) will be surveyed using questionnaires that include questions that will determine the problems encountered with WLAN particularly with the use of the antennas they currently utilise, the solutions they are implementing and the improvement they would like to suggest and impose with the current standards. It is important that the views of these people be collected since they are the ones who are immersed in the realities of the WLAN conditions. They will be able to provide insights that will help the researcher in evaluating the current IEEE standard. This study will be using the descriptive research method where the general part of the paper will be dedicated to the description of the subject in question. Descriptive research intends to present facts concerning the nature and status of a situation, as it exists at the time of the study (Creswell, 1994). It is also concerned with relationships and practices that exist, beliefs and processes that are ongoing, effects that are being felt, or trends that are developing. In addition, such approach tries to describe present conditions, events or systems based on the impressions or reactions of the respondents of the research (Creswell, 1994). The use of the descriptive method also suggests that the research will be focusing on obtaining qualitative data. Qualitative research is an umbrella that refers to various research traditions and strategies. The research will be carried out systematically. First, the researcher needs to review previous literature about the topic. This will allow the research the researcher to become familiar with what is already known about the topic. This will also allow the researcher to formulate the appropriate questionnaire that will be able to extract the most useful data. After the questionnaires have been completed, the researcher will have to tally the results and compare it with the findings of previous studies. If the finding of the research is the same as the findings of previous studies then the research can be supported by the findings of previous studies. On the other hand, if the findings of the research do not agree with past studies then the researcher must look back on previous studies to check if the findings of the studies are supported by other findings. This will ensure that the results of the research are not isolated and have been tested by other researches. 6.2 Schedule The Gantt chart below shows the schedule of activities involved in conducting the research study. Activity Date 1st Month 2nd Month 3rd Month 4th Month Data Gathering/Survey, Personal Interview     Review of earlier studies and related literature/ Analysis of data collected     Writing of the First Draft     Development, Testing, Analysis, Evaluation and Documentation     Revision of the study     Formulation of the conclusion     Completion of Writing     Printing and binding of documents     Submission      Deliverables            The research study will be organised as follows: A chapter describing the IEEE 802.11 A chapter describing the antenna used in WLAN and the problems using non-directional antennas A chapter describing the analysis of the problems A chapter that presents the data collected and the analyses of those data A chapter for the proposed solutions and the methods for testing the solutions A chapter that serves as documentations of the testing, calculations involved and evaluation of the proposed solutions Resources            As already mentioned, this research study is highly technical nature thus resources must be from reliable sources such as the IEEE itself that developed the standard that will be enhanced and the Association for Computing Machinery which is an organisation that publishes reliable sources about computing and related technology. ACM also has a digital library where various literatures can be accessed. The World Wide Web is also be used as a source where different latest articles and journals can be found. University and public libraries will also be used where books that discuss the basic concepts of the subject and topics involved can be found. The researcher will need the cooperation of technical professionals, technicians and engineers whose personal knowledge will be needed as they answer the survey questionnaires. The researcher will also need to collaborate with an ISP or a network company to test the proposed standard, determining its effectiveness as well as its shortcomings. References: Choudhury, R., Yang, X., Ramanathan, R., and Vaidya, N. (2002) Using Directional Antennas for Medium Access Control in Ad Hoc Networks, MOBICOM’02, ACM: Georgia, USA Creswell, J.W. (1994). Research design: Qualitative and quantitative approaches. Thousand Oaks, CA: Sage Dham, Vikram (2003) Link Establishment in Ad Hoc Networks Using Smart Antennas Thesis in Master of Science in Electrical Engineering, Virginia Polytechnic Institute and State University retrieved online on December 13, 2006 http://scholar.lib.vt.edu/theses/available/etd-05072003-180228/unrestricted/etd.pdf Erger, Mustafa (2002) IEEE 802.11 Tutorial, Department of Electrical Engineering and Computer Science, University of California Berkeley, Retrieved online on Dec. 13, 2006            http://www.eecs.berkeley.edu/~ergen/docs/ieee.pdf Frenzel, Louis (1994) Communication Electronics 2nd edition, Glencoe Macmillan/McGraw-Hill: Singapore Xu, Shugong Saadawi, Tarek (2003) Does IEEE 802.11 MAC Protocol Work Well in Multi-hop Wireless Ad Hoc Networks? Dept. of Electrical Engineering, City University of New York retrieved online on December 13, 2006            http://academic.csuohio.edu/yuc/mobile03/0415-xu.pdf  Zhu, Chenxi, Nadeem, Tamer and Agre, Jonathan (2005) Enhancing 802.11 Wireless Networks with Directional Antenna and Multiple Receivers, Fujitsu Laboratories of America, retrieved online on December 13, 2006 http://www.flacp.fujitsulabs.com/TM-PCR-TM-21.pdf Zhou, Hao (2006) The Improvements in Ad Hoc Routing and Network Performance with Directional Antennas, Department of Electrical and Communications Engineering, Helsinki University of Technology, Retrieved online on December 13, 2006            http://lib.tkk.fi/Dipl/2006/urn007316.pdf
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