Designing a Wireless Communications and Computing Network System with Wireless Security - Research Paper Example

DESIGNING A WIRELESS COMMUNICATIONS AND COMPUTING NETWORK SYSTEM WITH WIRELESS SECURITY AND SMART MOBILE ANTENNA TECHNOLOGY FOR A HOTEL WITH GARDEN AND CAR PARK Course Name: Code: Name: Submitted to: Abstract This work envisaged designing a wireless communications and computing network system with wireless security and smart mobile antenna technology for a hotel with garden and car park. A thorough study of the area is made and relevant data is gathered. Subsequently, a discussion on the planning and engineering process that can be used to design a microcellular radio system was made. A discussion on the problem areas those are associated with microcellular systems was made. Subsequently a comparison was provided between cell reuse patter of FCA of macro-cell and DCA were discussed. In the designing section, the required basic features of the communication system were discussed. Taking all these factors into consideration, a suitable option was recommended. Contents Abstract 3 Contents 4 Table of Figures 5 Image Credit 5 6 Section I: Introduction 1 1.1 Why is the modelling is important in engineering design 1 1.2 Background 2 1.3 Research Objective 3 2. Design and Theory 4 2.1 Concepts 4 2.2 Design Considerations 6 2.21. Design Difficulties 6 2.2.2Channel reuse ratios 8 3. Methodology 10 3.1 Deciding the technology 10 3.2 Design factors 11 3.3 Need Assessment 12 3.3 Site Survey 13 Coverage creation 16 4. Discussion and analysis 17 5. Limitations & Recommendations 18 References 19 Table of Figures Figure 1: Illustration of a cell system 5 Figure 2: Cochannel reuse ratio in FCA vs. DCA System [6] 9 Figure 3: A study of the type of interconnectivity and interoperability is essential to the success of the project. 13 Figure 4: Portion of the building with the with cell reuse pattern superimposed on it [1] 16 Figure 5: Planning the coverage region of a base station antenna on a specific-site of the hotel 16 Figure 6: Building layout with a base station antenna location 17 Image Credit http://realadventures.com/listingimages/1020/1020921/m_1020921c.jpg Section I: Introduction 1.1 Why is the modelling is important in engineering design The hospitality industry requires very high service levels, in which the internal communication structure is crucial for having reliable and efficient workflow, both for the front and the back-office. Besides, businesses and the guests expect the hotel to provide efficient personalised telephony with a direct line, a personal mailbox, wireless internet connections, integrated billing functions. Lack of an efficient internal communication management system may have adverse effect on its operations. For instance, it is important to have the workflow in such a way that it is possible to track every action that takes place in the hotel. Moreover, requests or action needs to be responded instantaneously, be it a request for room service, checkout or to signal a problem, or situation with the operation of the hotel. Traditional indoor communication systems in the hotels have been limited to cordless phones, walkie-talkies, pagers and more recently standard cell phones. All of them have their limitations and disadvantages. On a different technological front, WiFi wireless Internet services are already common in most hotels but with limited access through standard socket connections in the rooms and a few hotspots around the hotel premises. Similarly, Bluetooth technology is also prevalent, apparently with limited connectivity with other existing systems. Therefore, providing hassle-free communication system that could provide seamless integration over the spectrum of advanced personalised services such as interactive television and WiFi wireless Internet access along with the provision of management and control of operation of the hotel is of considerable importance to all the stakeholders in the hospitality industry. 1.2 Background A major challenge of the wireless communication is in the area of integrated services that share resources to allow all types of data, voice and video information to be conveyed between users independent of their locations [1]. Besides, the need for a seamless integration with macro-cellular wireless communication systems with in-building wireless communication system is always prevalent. The in-building/multi-building communication system presents many challenges to designers such as: 1. Non- line of sight communication nature of requirement 2. Attenuation and reflection of signal strength due to obstructions by physical objects 3. Movement of equipment and users 4. Multipath effects 5. Shadowing effects 6. Inter symbol interference (ISI) 7. Co-channel interference All these issues are dealt with at sufficient length in the succeeding sections. However, it is apparent that, the cellular mobile radio system designer needs have sound understanding of many aspects of telecommunication such as radio propagation, frequency regulation and planning, modulation, antenna design, transmission planning, switching exchange, teletraffic and software design; making it a challenging task. [2]. Besides, he also must be thorough in the basic cellular technology which the regular hexagonal grid structures, channel assignment, cell splitting, overlaid cells, call processing, radio propagation concepts and other principles [2]. An in-building/multi-building cellular system or a microcellular system as that of a macro one needs a well-planned phased approach involving estimation of future scenarios, collection of measurement data and reconfiguration of system if it falls deficient to the design objective [3]. Taking all these aspects into consideration, the designer selects the sites, determines the equipment requirement and channel availability [3]. Accordingly, engineering even a microcellular system requires considerable adequate information on several aspects such as service area under consideration, traffic details, choice of reuse pattern, positioning of the base stations, (5) radio coverage prediction, design check-ups, and Field measurements [2]. 1.3 Research Objective With all these issues, situations and problems in place it is imperative that a wireless system be designed to provide trouble free service while taking these aspects into consideration. In the present work, it is proposed to design a wireless communications and computing network system with wireless security and smart mobile antenna technology for a hotel with garden and car park. The mathematical properties of hexagonal geometry were taken into consideration to achieve uniform coverage and reduction in co-channel interference. Basic mathematical properties of hexagonal cellular geometry were taken into consideration to achieve uniform coverage and reduction in co-channel interference. Characteristics of the radio propagation in the region, impairments in signal and the antenna systems required for different cells and sites were also accounted for. 2. Design and Theory 2.1 Concepts Young (1979) suggests that as early as 1970’s, Bell Telephone Laboratories developed the concept of cellular telecommunications using radio channel at less than horizon distance [4]. In a cellular system, a large number of mobile units are located in a larger area making communication within each other in a limited frequency system. A mobile unit means a radio terminal that can move while the communication is still in progress [5]. In the cellular system, the service area is divided into cells with assigned frequency range for each cell, which is the unit of RF coverage. In each cell, a base station transmits from a fixed cell site location, which is usually positioned in the centre of the cell, to mobile stations or subscriber units (Fig. 1). Figure 1: Illustration of a cell system By splitting the existing cells into smaller cells, and in the process reusing the frequencies more often in the stipulated geographic area, the capacity of cellular system can be increased. However, since there is a limit to the splitting as it cannot be split beyond a certain number of times. The lower limit of cell radius of most cellular systems, referred to as macro systems, are in the range of 1 to 1.5 km., although cell radius of 0.5 km is also known to be employed [6]. To provide wireless communication service microcellular technologies are being used. The primary difference between a microcell architecture and macrocell architecture are (1) the radius of microcells are usually less than 1 km, (2) the mobile terminals of a micro system radiates considerable power levels, and (3) in a microcell the available channels are not partitioned, which implies that all channels are available in every cell; whereas in macrocell system, channels have permanently pre-allocated. This arrangement is otherwise known as fixed channel assignment (FCA) [6] In a microcell system, it is not feasible to preallocate channels using fixed channel assignment (FCA) principles. In place of that here channels are allocated at call setup time by either the base station or the mobile terminal. This is done to minimise interference. This process of channel allocation is referred to as Dynamic Channel Assignment (DCA). While, in the FCA arrangement of macrocell system, a simple relationship between the cluster size C and the ratio of signal to interference (S/I) of a receiver at the location of the cell boundary; no such provision is available for dynamic channel assignment arrangement of microcell system [6] 2.2 Design Considerations The purpose of any cellular system, be it micro- or macro-cell, is to transmit at high enough power levels to provide satisfactory quality of transmission and low enough not to cause interference with the nearest station, where the same channel is reused, thus ensuring multiple use of the channel in the same geographical area [7]. Consequently, greater is the reuse distance and the lower the power output levels employed within the cell sharing a common cell, it will have that much lower chances of interference [7]. Therefore, the greater the reuse distance and the lower the power levels used in cells sharing a common channel the lower the probability of interference. The detailed of the functionality and principles are dealt with in the subsequent section. 2.21. Design Difficulties As stated earlier, the in-building/multi-building communication system presents many challenges to designers. For instance, there is hardly an occasion where there would be a line of sight communication between the transmitter and the receiver. Moreover, signal strength is greatly attenuated and reflected by physical obstructions such as walls, doors and etc. Another problem occurs due to the movement of equipment and users, which adversely affects the RF propagation channel, thereby creating a constantly changing and difficult to predict propagation environment [1] However, among some of the biggest issues that concerns designing of microcellular radio systems are multipath and shadowing effects. When the transmitted signal arrives at the receiver through several different paths caused due to reflection, scattering, direction and refraction effects on the RF signal because of obstructions in the environment, a multipath propagation condition develops (Collin, 1985) [8]. The obstructions may either be stationary objects such as walls or moving objects. Moreover since the paths are generally not of the same length, the receiver faces additional problem of receiving transmitted signal components at different times. Rappaport (1996) states that in narrowband communication systems, the existence of multipath signal components creates Rayleigh fading to occur at the receiver [8], [1] As a result, the signal strength observed at the receivers varies with time. Shadowing also though caused by obstructions present in the environment, but it is generally associated with blockage of RF signal due to presence of immobile objects such as walls or buildings. The variation in received signal strength because of shadowing usually takes place comparatively slowly at the location of the receiver [8]. In addition to the problems generated by multipath and shadowing conditions, the in-building/multi-building communication system face is that of interference. While in wideband communication systems, multipath delays affect the received signal quality, in the case of case of interference, it takes the form of frequency selective fading [8]. Due to receiving multiple signal components, digital wireless communication systems are likely to face interference. For instance, the component of a previous transmitted signal may arrive at the receiver at the same time. This type of interference caused due to interference between the components of signal is called as inter-symbol interference (ISI). Rappaport (1996) states that the ISI increases with the signalling rate, thereby limiting the maximum rate of data for any un-equalised wireless communication system [8]. Another problem that hinders the efficiency of wireless communication is due to co-channel interference. Co-channel interference takes place due to two or more users use the same communication channel in close proximity [9]. However, this problem can be addressed to some extent during the design phase of the wireless system through optimal channel assignment and adopting a sound base antenna locating strategy [9], [8], [10]. 2.2.2Channel reuse ratios The figure below indicates how within a cellular communications system, channel reuse is done. It also provides a comparison between the fixed channel assignment (FCA) process of macro-cell system and the dynamic channel assignment (DCA) process of microcell system architecture. Jones (2007) suggests that in an FCA system, the available channels are divided into ‘C’ number of sets, where ‘C’ is the cluster size. Each channel set is deployed within the boundary of the hexagonal cells in such a manner that the distance between cells using the same channel set when divided by the cell radius produces a constant referred to as cochannel reuse ratio (CRR) [6]. Jones cites the example of the figure below to explain that the FCA cluster size C is 3 and the nominal CRR is (3C)1/2 = 3.0, but given the design constraints in the system, the minimum possible CRR is 2.0. Jones argue that while in the FCA system, the S/I requirement of the particular technology determines the minimum cluster size and the pattern of channel assignment; which however, is not applicable in the DCA microcell setup, since, there is no channel partitioning available in this arrangement. Here every terminal is equipped with the capability of using any channel in any cell without a guaranteed minimum CRR [6]. Figure 2: Cochannel reuse ratio in FCA vs. DCA System [6] Jones adds that the minimum CRR in a microcell system is a function of pure RF blocking at a receiver, which means the establishment of a radio link is prevented due to interference, and the reuse ratio probabilities cannot be predicted using the macrocell design principles [6]. In summary, for designing microcellular radio systems, though many of the principles applicable to macrocellular systems can be employed, yet, important considerations such as channel reuse principles cannot be followed altogether. 3. Methodology 3.1 Deciding the technology As a first step for designing a radio communication system for a hotel with a car park and garden will require determining the technology that is to be adopted taking into consideration such factors as service area, type of connectivity required, security aspects, traffic demand and so on. For a hotel project such as this, a personal communication system (PCS) with interoperability with macro-cellular services and other wireless technologies such as WiFi and Bluetooth and even a pbx system appears to be ideal. Personal communication systems are more flexible and have the premise of providing communication facility to anyone and anywhere [11]. Therefore, the fundamental features that needs to be planned for such a communication system for the hotel would need among other things, network capacity uniform coverage, low equipment and infrastructure cost very small, inexpensive and easy-to-use base stations (BS’s) Present day microcellular systems are also providing all these features though their cost remains to be reduced further. Most microcells are primarily “remote radiation site”, having the RF or IF mobile radio signals transmitting facilities over and optimal link or over a point to point radio link to a microwave distribution point, which acts as the centre of the microcell. Siting a base station involves prediction of radio coverage with errors in path loss and identifying a suitable structure in the hotel property for erecting the base station. The microwave propagation in microcells is essentially determined by the topology in the property. . In cordless systems such as European Cordless Telecommunication System and digital European cordless telecommunication system (DECT), base stations are very small and inexpensive and also lately designed for cellular networks and also provide the high capacity required for personal communication systems. These are therefore ideal for small hotel projects and have been implemented successfully. 3.2 Design factors After having decided the technology to be used, the design steps are to be planned. The following design steps were undertaken while designing the cellular radio system for the hotel: 1. Catering to path loss 2. Catering to floor attenuation 3. Received signal strength 4. Predicting received signal strength 5. Accounting for noise 6. Accounting for interference 7. Coverage area creation 8. Assessing accuracy 9. Determining antenna pattern 10. Validating for multi-building scenarios 3.3 Need Assessment A detailed study of the need of the hotel is undertaken and data pertaining to the type of interconnectivity and interoperability is gathered. Figure 3: A study of the type of interconnectivity and interoperability is essential to the success of the project. 3.3 Site Survey A rigorous site survey would go a long way in the successfully designing the cellular system. The following is a site survey checklist developed by CISCO for LAN, however would be useful for this case also. 1. Facility diagram. Obtaining or drawing a set of building blueprints. If not available, prepare a floor plan drawing that depicts the location of walls, walkways, etc. 2. Visually inspect the facility. Walk through the facility before performing any tests to verify the accuracy of the facility diagram. Note any potential barriers that may affect the propagation of RF signals. For example, a visual inspection will uncover obstacles to RF such as metal racks and partitions, items that blueprints generally dont show. 3. Identify user areas. On the facility diagram, mark the areas of fixed and mobile users. In addition to illustrating where mobile users may roam, indicate where they will not go. 4. Determine preliminary access point locations. By considering the location of wireless users and range estimations of the wireless LAN products youre using, approximate the locations of access points that will provide adequate coverage throughout the user areas. Plan for some propagation overlap among adjacent access points, but keep in mind that channel assignments for access points will need to be far enough apart to avoid inter-access point interference. Be certain to consider mounting locations, which could be vertical posts or metal supports above ceiling tiles. Be sure to recognize suitable locations for installing the access point, antenna, data cable, and power line. Also think about different antenna types when deciding where to position access points. An access point mounted near an outside wall, for example, could be a good location if you use a patch antenna with relatively high gain oriented within the facility. 5. Verify access point locations. Use an RF site survey tool that identifies the associated access point, data rate, signal strength, and signal quality. You can load this software on a laptop and test the coverage of each preliminary access point location. Install an access point at each preliminary location, and monitor the site survey software readings by walking varying distances away from the access point. Theres no need to connect the access point to the distribution system because the tests merely ping the access point; however, youll need AC power. So be sure to take along an extension cord, and learn where AC outlets exist. Take note of data rates and signal readings at different points as you move to the outer bounds of the access point coverage. In a multi-floor facility, perform tests on the floor above and below the access point. Keep in mind that a poor signal quality reading likely indicates that RF interference is affecting the wireless LAN. Based on the results of the testing, you might need to reconsider the location of some access points and redo the affected tests. 6. Document findings. Once satisfied that the planned location of access points will provide adequate coverage, identify on the facility diagrams recommended mounting locations. Of course the installers will need this information. Also, provide a log of signal readings and supported data rates near the outer propagation boundary of each access point as a basis for future redesign efforts. Figure 4: Portion of the building with the with cell reuse pattern superimposed on it [1] Coverage creation Figure 5: Planning the coverage region of a base station antenna on a specific-site of the hotel Figure 6: Building layout with a base station antenna location The figure above depicts a typical building layout with a base station antenna, represented by a circle, and an interference source antenna, represented by a diamond, having been placed on the current floor. Another base station antenna, represented by a circle that has been crossed out, has been positioned on some other floor of the building. 4. Discussion and analysis While designing the cellular system for the hotel with a garden and a car park, a thorough study of the area is made and relevant data is gathered. Subsequently, a discussion on the planning and engineering process that can be used to design a microcellular radio system was made. A discussion on the problem areas those are associated with microcellular systems such as non-line of sight nature of communication requirement, attenuation and reflection of signal strength due to obstructions by physical objects, movement of equipment and users, multipath effects, shadowing effects, inter symbol interference, co-channel interference and so on. Subsequently a comparison was provided between cell reuse patter of FCA of macro-cell and DCA were discussed. In the designing section, the required basic features of the communication system was discussed such as network capacity, uniform coverage, low equipment and infrastructure cost and very small, inexpensive and easy-to-use base stations. Taking all these factors into consideration, it was decided that an advanced cordless technology that is capable of providing interoperability with macro-cellular services and other wireless technologies such as WiFi and Bluetooth along with traditional wired telephone system and capable of transmitting voice, video and data appears to be ideal It is observed that the DECT technology is nowadays able to provide all these facilities. 5. Limitations & Recommendations Designing a cellular system for a hotel spread over a small area requires personal involvement and visitations to the site, which would requires institutional support to gather authentic data and undertake fool proof planning. This study suffers greatly on account of this. It is recommended that for undertaking such projects adequate institutional support be made available either through sponsorship or governmental grants. References [1] Roger R. Skidmore, A Comprehensive In-Building and Microcellular Wireless Communication System Design Tool, 1997, Thesis. [2] Michel Daoud Yacob, "Cell Design Principles," Wireless, pp. 319-330, 1996. [3] "Design of Wireless System: A Case Study," in Design of Wireless System: A Case Study., ch. 13, pp. 337 - 354. [4] W.R. Young, "Advanced Mobile Phone Service: Introduction, Background and Objectives," Bell System Technical Journal, vol. 58, no. 1, pp. 1-14, 1979. [5] Kamil Sh. Zigangirov, "Introduction to Cellular Mobile Radio Communciation," in Theory of Code Division Multiple Access Communication.: Institute of Electrical and Electronics Engineers, 2004, ch. 1, pp. 1-35. [Online]. http://media.wiley.com/product_data/excerpt/24/04714571/0471457124.pdf [6] Brendan C. Jones, Cochannel Reuse Ratio Distributions in Dynamic Channel Assignment Microcellular Systems, 2007, Research Paper. [7] W.C.Y. Lee, Mobile Communications Design Fundamentals. Indianapolis: Howard W. Sams. [8] T. S. Rappaport, Wireless Communications Principles and Practices. New Jersey: Prentice-Hall Inc., 1996. [9] R.E. Collin, Antennas and Radio Wave Propagation. New York: McGraw-Hil, 1985. [10] H. D. Sherali, C.M. Pendyala, and T. S. Rappaport, "Optimal Location of Transmitters for Micro-Cellular Radio Communication System Design," IEEE Journal on Selected Area in Communication, vol. 14, no. 4, pp. 662-673, May 1996. [11] Raymond Steele, James Whitehead, and WC Wongs. (1995) System Aspects of Wireless Radio. [Online]. http://www.cs.bilkent.edu.tr/~korpe/courses/cs515-fall2002/papers/system-cellular-radio.pdf [12] Living Stone. (2008) Communcation System Leads the Hospitality Industry into the Future. [Online]. http://enterprise.alcatel-lucent.com/private/active_docs/customer_references/case_study_EN_hospitality%20industry%20update%20.pdf [13] cictr.ee.psu.edu. Broadband Wireless Local Area Networks and Remote Sensing. [Online]. http://cictr.ee.psu.edu/research/wc/index.html [14] Brendan C. Jones and David J. Skellern, "SYSTEM DESIGN FOR CONTIGUOUS CELL COVERAGE IN HIGH DENSITY MICROCELLULAR NETWORKS," in 3rd URSI International Symposium on Signals, Systems and Electronics (ISSSE ’95), San Francisco, 1995, pp. 263-266. [15] support.avaya.com. (2010) These Application Notes describe a solution for supporting wireless interoperability between the Ascom wireless IP-DECT SIP solution. [Online]. http://support.avaya.com/css/P8/documents/100073667 Read More