WIRELESS FIDELITY (Wi-Fi) BROADBAND NETWORK TECHNOLOGY: AN OVERVIEW WITH OTHER BROADBAND WIRELESS NETWORKS

by

Chris A. Nwabueze, M. Eng., MNSE, MNIEEE, MIEE. Silas A. Akaneme, M. Eng., MNSE, MNIEEE, MIEEE Dept. of Electrical/Electronic Engineering, Anambra State University, Uli. E-mail: [email protected].

ABSTRACT Wireless Fidelity (Wi-Fi) broadband network technology has made tremendous impact in the growth of broadband wireless networks. There exists today several Wi-Fi access points that allow employees, partners and customers to access corporate data from almost anywhere and anytime. Wireless broadband networks are expected to grow in terms of broadband speed and coverage, while Wi-Fi can be integrated with WiMAX networks to provide Internet connectivity to mobile Wi-Fi users. This paper explores the Wi-Fi broadband wireless network technology, its uses, advantages and disadvantages, comparison with other broadband wireless networks and integration with WiMAX network.

Key Words: Broadband, Wireless Fidelity (Wi-Fi), World Wide Interoperability for Microwave Access (WiMAX), IEEE 802.11 standards.

1.0 INTRODUCTION 802.11a [12]. Wi-Fi is owned by the Wi-Fi Wi-Fi stands for “Wireless Fidelity” and Alliance which is a consortium of separate was used to describe Wireless LAN and independent companies agreeing to a (WLAN) products that are based on the set common interoperable products based IEEE 802.11 standards. Wi-Fi uses both on the family of IEEE 802.11 standards single carrier direct-sequence spread [11]. spectrum radio technology and multi-carrier Wi-Fi certifies products via a set of OFDM (Orthogonal Frequency Division established test procedures to establish Multiplexing) radio technology. These interoperability. Those manufacturers that regulations then enabled the development are members of Wi-Fi Alliance whose of Wi-Fi and its onetime competitor products pass these interoperability tests HomeRF, and Bluetooth. Wi-Fi’s first can mark their products with the Wi-Fi logo wireless products were brought on the [10]. market under the name WaveLAN with Wi-Fi technologies have gone through speeds of 1 Mbit/s to 2 Mbit/s and several generations since their inception in standards designed as IEEE 802.11b, and 1997. Wi-Fi is supported to different

71 72 CHRIS A. NWABUEZE & SILAS A. AKANEME extents under Microsoft Windows, Apple standard. The two broadband mobile Macintosh and open source UNIX and wireless network technologies here are the Linux operating systems. Third Generation (3G) and Fourth The intent of this paper is to examine Generation (4G) networks. The 3G Wi-Fi fixed broadband technology, explore standards are defined by ITU-T, IMT2000 its relationship with other networks (fixed and the standards for the 4G are still and mobile), its advantages and evolving. disadvantages, and future prospects in broadband wireless network technology, 2.1 Fixed Broadband Wireless Network especially its integration with WiMAX Fixed broadband wireless technologies can network. be defined as high-speed wireless networks that connects to stationary locations and are 2.0 B R O A D B A N D W I R E L E S S intended to serve nomadic users [5]. NETWORKS Wireless Fidelity (Wi-Fi) and Worldwide Broadband wireless networks can be Interoperability for Microwave Access categorized into two types: fixed and (WiMAX) technologies which are mobile wireless. The broadband fixed discussed in this paper are governed by wireless network technologies of interest IEEE 802.11 and 802.16 specifications are Wireless Fidelity (Wi-Fi), which is an respectively. There specifications are as IEEE 802.11 standard and Worldwide shown in Table 1. Interoperability for Microwave Access (WiMAX), which is also an IEEE 802.16

Table 1: Fixed Broadband Wireless Technologies Technology Standard Usage Throughput Range Frequency Wi-Fi 802.11a WLAN # 54 Mbps # 100 m 5 GHz Wi-Fi 802.11b WLAN # 11Mbps # 100 m 2.4 GHz Wi-Fi 802.11g WLAN # 54Mbps # 100 m 2.4 GHz WiMAX 802.16d WMAN # 75Mbps (20 MHz BW) 5-10 km Sub11GHz WiMAX 802.16e WMAN # 75Mbps (20 MHz BW) 5-10 km 2.4 GHz

* Wireless Fidelity Network Fi standards are given in Table 1. Wi-Fi as Technology a high-speed wireless technology has Wi-Fi is the first high-speed fixed wireless enjoyedbroad deployment, most notably in technology to enjoy broad deployment, hotspots around the world including homes therefore there exist today many wireless and offices, and increasingly in cafes, hotels products based on Wi-Fi technologies and airports [4]. which include the approved IEEE 802.11a, Today, Wi-Fi hotspots are very b and g specifications, as well as the yet-to- popular and have been applauded for their be ratified 802.11n specification [8]. The ability to improve productivity for mobile different characteristics of the various Wi- corporate users. Wi-Fi is limited by its

NIGERIAN JOURNAL OF TECHNOLOGY, VOL. 28 NO.1, MARCH 2009 WIRELESS FIDELITY (Wi-Fi) BROADBAND NETWORK TECHNOLOGY: AN OVERVIEW WITH OTHER ... 73 coverage area and high-speed connectivity * Worldwide Interoperability for is only possible as long as a user remains Microwave Access (WiMAX) within range of the wireless access point, Network Technology which is optimally within 100m. Worldwide Interoperability for Microwave The Wi-Fi architecture consists of a Access (WiMAX) is a fixed broadband base station to which wireless hosts are wireless technology that is gaining connected in order to access network acceptance and delivers last kilometer resources. The base station is responsible broadband connectivity in a larger for sending and receiving data to and from geographic area than Wi-Fi. It provides the wireless host that is associated with the canopies of anywhere from one to ten base station. The connection between the kilometers wide. Such WiMAX coverage host and the base station is the wireless range provides fixed and nomadic wireless communication link. This communication broadband connectivity without necessarily link is responsible for data transport having a line-of-sight (LOS) with a base between the base station and the hosts [6]. station [2]. WiMAX will also enable greater The main strength of Wi-Fi is its mobility, higher speed data applications, simplicity and ease of deployment given range and throughput [5]. that it uses unlicenced radio spectrum. Wi- WiMAX uses the IEEE 802.16 Fi allows users to be mobile for up to 100m standards specifications (802.16d and g). from the base station and still have access The IEEE 802.16d specification is primarily to the network. Also, the cost for rolling out tailored to wireless wide area networks this wireless solution is low because no (WWANs). The IEEE 802.16e specification expensive wiring is required. Finally, there on the other hand is primarily used for is also availability of many other Wi-Fi mobile wireless metropolitan networks compatible products, which can (WMANs). These two specifications render interoperate with other network WiMAX architecturally ideal for the last technologies [9]. kilometer, the backhaul, Internet Service As a fixed broadband access Providers, cellular base stations that bypass technology, Wi-Fi has its weaknesses. The PSTN’s, hotspots, and enterprise networks user can only use the technology within the [4]. confines of 100m radius thus limiting the Abilities such as high bandwidth level of mobility. Also, the fact that the frequencies between 2 GHz and 11 GHz, technology operates in the 2.4 GHz band makes WiMAX ideal for data transport. which does not require any licensing WiMAX has a total range of up to 50 km renders it susceptible to interference from [1]. This ability is enhanced by WiMAX’s other devices such as Bluetooth, cordless cell radius of 5 -10 km. Also, WiMAX has phones, etc. In terms of security, the the ability to support various data encryption standard used such as Wired transmitting rates of up to 75 Mbps as Equivalent Privacy (WEP) has been shown shown in tables 1 and 2. There are several to be easily breakable [5]. advantages that can be derived from the

NIGERIAN JOURNAL OF TECHNOLOGY, VOL. 28 NO.1, MARCH 2009 74 CHRIS A. NWABUEZE & SILAS A. AKANEME deployment of WiMAX. Firstly, it supports 2.2 Mobile Broadband Wireless higher throughput rates, higher data speed Network rates and wider operating range. These Mobile Wireless evolution started with the make the technology very useful for first generation (1G) networks, which was deployment in bad terrain areas or in implemented based on Frequency Division environments with limited wired Multiple Access (FDMA) and these infrastructure. Secondly, WiMAX supports networks were basically for voice and interfaces easily to other wired and communication. The 2G (second wireless technologies such as Ethernet, generation) network that replaced the 1G ATM, VLANs, and Wi-Fi. Thirdly, are still mainly for voice applications. WiMAX provides network connectivity that These 2G systems provided circuit- explores multipath signals without the switched data communication services at stringent requirement of a direct line of low speed. The competitive rush to design sight. Finally, WiMAX provides a better and implement digital systems led to a Quality of Service (QoS) by taking variety of different and incompatible advantage of smart antenna technology that standards [5]. utilizes the spectrum more efficiently. The 2.5G is an enhancement of the 2G The main drawback to the deployment technologies to provide increased data of WiMAX is proprietary equipment [4]. capacity on the 2G networks. This led to the WiMAX introduction of technologies such as equipment must be able to utilize power General Packet Radio Service (GPRS) and efficiently in order to deliver optimum Enhanced Data Rates for Global Evolution functionality. For WiMAX, output power (EDGE). The Third Generation G3 mobile usage is based on a ranging process that networking systems has replaced the 2G determines the correct timing offset and and 2.5G networks. The 3G systems have power settings. higher quality voice channels, as well as The transmissions for each subscriber broadband data capabilities, up to 2 Mbps. station are supposed to be such that they Unfortunately, the 3G has no single arrive at the base station at the proper time standard due to the clamour to replace the and at the same power level. When 2G networks by various equipment WiMAX is deployed outdoors, in non-line manufacturers. The 4G is expected to of sight environments it may encounter replace the 3G. Features of the two delay, which can cause potential broadband mobile technologies intersymbol interference. Though the use of (3G and 4G) are compared with fixed Orthogonal Frequency Division broadband technologies in table 2. Multiplexing (OFDM) is meant to try and alleviate this problem, OFDM usage has the 3.0 WIRELESS FIDELITYF (Wi-Fi) problem of generating phase noise, which NETWORK IMPLEMENTATION increases the RF subsystem cost and A Wi-Fi enabled device such as a PC, game complexity [5]. console, cell phone, MP4 player or PDA

NIGERIAN JOURNAL OF TECHNOLOGY, VOL. 28 NO.1, MARCH 2009 WIRELESS FIDELITY (Wi-Fi) BROADBAND NETWORK TECHNOLOGY: AN OVERVIEW WITH OTHER ... 75 can connect to the Internet when within in enhancing Wi-Fi. range of the wireless network connected to the Internet. The area covered by one or 3.1 Advantages of Wi-Fi Technology more interconnected access points is called i. Wi-Fi allows LANS to be deployed a hotspot. Hotspots can cover as little as a without cabling for client’s devices, single room with wireless-opaque walls or typically reducing the costs of network as much as many square kilometers covered deployment and expansion. Spaces by overlapping access points. Wi-Fi has where cables cannot be run, such as been used to create mesh networks, and are outdoor areas and historical buildings, used in community networks. can host wireless LANS. Wi-Fi also allows connectivity in peer- ii. Wi-Fi is widely available in more than to-peer (wireless ad-hoc network) mode, 250,000 public hotspots and tens of which enables devices to connect directly millions of homes, corporate and with each other. This connectivity mode is university campuses worldwide . Wi- useful in consumer electronics and gaming Fi Protected Access (WPA and applications. Business and industrial WPA2) is not easily cracked if strong application of Wi-Fi is widespread as of passwords are used and WPA2 2007. In business environments, increasing encryption has no known weakness. the number of Wi-Fi access points provide New protocols for Quality of Service redundancy, support for fast roaming and make Wi-Fi more suitable for latency- increased overall network capacity by using sensitive applications. more channels or creating smaller cells. Wi- iii. As of 2007, wireless network adapters Fi enables wireless voice applications are built into most modern laptops. (VoWLAN or WVOIP). Over the years, The prices of chipsets for Wi-Fi Wi-Fi implementations have moved toward continues to drop, making it an ‘thin’ access points, with more of the economical networking option network intelligence housed in a centralized included in ever more devices. Wi-Fi network appliance, relegating individual has become widespread in corporate Access Points to be simply ‘dumb’ radios. infrastructures, which also helps with Presently, Wi-Fi installations can provide a the deployment of Real Time Location secure computer networking gateway, Systems (RFID) technology that can firewall, intrusion detection system and ride on Wi-Fi [7]. other functions. Wi-Fi is publicly available iv. Different competitive brands of access at Wi-Fi hotspots provided either free of points and client network interfaces charge or to subscribers through various are Inter-operable at a basic level of providers. Free hotspots are often provided service. Products designated as ‘Wi-Fi by businesses such as hotels, restaurants, Certified’ are backwards inter- and airports who offer the services to attract operable. Wi-Fi is a global set of or assist clients. Metropolitan-wide Wi-Fi standards. Unlike mobile telephones, (Mu-Fi) is currently enjoying great success any standard Wi-Fi device will work

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anywhere in the world. access and interfere with the use of other access points by others, caused 3.2 Disadvantages of Wi-Fi Technology by overlapping channels in the i. Wi-Fi networks have limited range. A 802.11g/b spectrum, as well as with typical Wi-Fi home router using decreased signal-to-noise ratio (SNR) 802.11b or 802.11g with a stock between access points. This can be a antenna might have a range of 32m problem in high-density areas, such as (120ft) indoors. Range also varies with large apartment complexes or office frequency band. Wi-Fi in the 2.4 GHz buildings with many Wi-Fi access frequency block has slightly better points. Additionally, other devices use range than Wi-Fi in the 5 GHz the 2.4 GHz band; microwave ovens, frequency block. Outdoor range with security cameras, Bluetooth devices, improved (directional) antennas can be Amateur radio, video senders, and several meters or more with line-of- cordless phones, can cause significant sight. additional interference. General ii. Wi-Fi performance also decreases guidance to those who suffer these exponentially as the range increases. forms of interference or network Wi-Fi is also less reliable and fast as crowding is to migrate to a Wi-Fi Ethernet or other cable systems. 5GHz product, (802.11a or the newer 802.11g networks have a maximum of 802.11n) as the 5 GHz band is 54 Mbit/s while cables can reach relatively unused and there are many speeds of 1000 Mbit/s or more. Wi-Fi more channels available. This also is not suitable for servers or users who requires users to set up the 5 GHz need fast LAN access. In practice, band to be the preferred network in the measured rates across the Wi-Fi client to configure each network band network will be much less than the to different name. headline rate, so 5 Mbit/s is typical as iv. Each node on the network is typically a real, measured transfer rate. 802.11n able to see all the communication improves this, but again does not between other nodes and the access achieve the headline rate for real use. point, allowing network traffic to be For Internet access, those with faster easily captured with a packet snuffers. broadband rates- such as 20 Mbit/s Hence, when a Wi-Fi network is not will notice an increase in performance encrypted, as most public hotspots are, using a wired connection rather than the network is vulnerable to sidejack Wi-Fi. This is because of protocol attacks. overheads. v. It is also an issue when municipalities, iii. Wi-Fi pollution, or an excessive or other large entities such as number of access points in the area, universities, seek to provide large area especially on the same or coverage. Everyone is considered neighbouring channel can prevent equal for the base standard without

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802.11e/WMM when they use the where reliability is required [12]. band. This openness is important to the success and widespread use of 2.4 GHz Wi-Fi, but makes it unsuitable for most public service functions or

4.0 COMPARISON OF Wi-Fi NETWORK WITH OTHER BROADBAND NETWORKS Table 2: Comparison of Broadband Wireless Technologies Technology Wi-Fi WiMAX 3G 4G Design 1997 2002 1990 2000 Implemented 2002 2006 2002 2010 Standard 802.11 802.16 WCDMA, One standard (a,b,g) (d,e) CDMA2000,etc expected Throughput # 54 Mbps # 75 Mbps $ 2 Mbps # 200 Mbps Multiplexing DSSS/OFDM OFDM WCDMA, OFDM & CDMA2000 OFCDM Frequency 2.4 & 5 GHz 2 & 11 GHz 900, 1800, 1900 2-8 GHz & 2100 MHz Usage WLAN WMAN WWAN WWAN Coverage # 100m # 50km Up to 10km $ 50km Services Fixed Wireless Fixed wireless Mobile wireless Mobile wireless broadband multimedia broadband multimedia Air Interface OFDMA OFDMA/FDD CDMA2000/ OFDMA/ WCDMA OFCDMA

Table 2 shows a comparison of Wi-Fi OFDMA for Wi-Fi, to OFDMA/FDD for technology with other wireless broadband WiMAX, CDMA2000 or W-CDMA for technologies discussed in this paper. Each 3G, and OFDMA/OFCDMA for 4G. The of the broadband wireless technologies has throughput of Wi-Fi is 54 Mbps, 75 Mbps many standards, except for the 4G where for WiMAX, 2 Mbps for 3G and up to 200 one single standard is expected. Wi-Fi is Mbps for 4G. best deployed for Wireless Local Area While mobile wireless technologies Network (WLAN) with limited coverage, cater for mobile users that need access to while the 3G and 4G are well suited for the network with large geographical area, Wireless Wide Area Network and the fixed wireless technologies meet the need WiMAX is suited for Wireless for broadband services at the last kilometer Metropolitan Area Network. Wi-Fi has a where traditional wired infrastructure does coverage area of just 100m, WiMAX a not exist due to the terrain or not cost coverage of 50 kilometers which is also the effective. In terms of cost and easy expected coverage of 4G, while the 3G deployment, Wi-Fi is cost effective and has coverage is up to 10 km. The Air Interface considerable high data transfer rate. of the various technologies differs from

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