Investigation of Wireless Metropolitan Area Networks Effect on Information and Communication Technology Development
Hossein Ghaffarian1, Mahboobeh Afzali
1Iran University of Science and Technology, Narmak, Tehran, Iran Email:Ghaffarian@iust.ac.ir
2Bardsir Islamic Azad University, Bardsir, Kerman, Iran Email: Afzali_mahboobeh@yahoo.com
Abstract: In the new millennium, world has experienced a fast development in information and communications technology (ICT) and divide gap has grown between poor and rich, developed and undeveloped countries. In this situation, lack of attention to outland and rural zones, makes variant prejudices between people, and finally, it causes wide variety of unorganized problems in the countries and serious problems for governments. An efficient low cost developing is the key note in ICT development. While lack of communication infrastructures in rural and outland zones, will increase costs.
Because of worldwide approval of wireless networks, using Wireless Metropolitan Area Networks can address an efficient low cost way for developing ICT infrastructures. In this paper, we will consider role of these networks in development of ICT infrastructures and challenges facing them.
Also, we will compare them with other existing communication technologies with respect to performance and security parameters in order to establish which technology meet to wideband, high speed and low cost connections requirements.
1. Introduction
Information and Communication Technology (ICT) is one of the sample technologies that are a basic criterion in economic and industrial human society developments. This technology is the result of a comprehensive thought that has been extended since second half of past century.
Today, ICT impacts on social, cultural, political and economical aspects of human lives.
Traditional ICT tools like TV, radio and telephone show their worth in rural areas’
development; but World Wide Web (Internet) and mobile phones’ developments produce large amounts of information, products, capital and thought.
ICT development has its own communication infrastructures. Primary ICT development has been done in many countries based on low costs wired telephone networks. But rapid increasing of user units and wide band services like video conference, VoIP, virtual learning and etc, need wide band communication infrastructures.
Today, Traditional wide band wired technologies like fiber optic, xDSL and ISDN are used to meet these wide band needs; but their setup, development and preservation costs cause serious doubts to development these structures on outland zones like suburban and rural areas. With respect to this, new cost and quality efficient arrived standards like IEEE 802.11, IEEE 802.16 and IEEE 802.20 have a rapid grow in communication network world.
The remainder of this paper is organized as follows. Section 2 introduces ICT effects on today's life and investigates some of rural area ICT development on the world. Section 3
describes types of fast wide band networks. WiMAX structure will be specified in section 4.
Section 5 clarifies WiMAX networks in comparison with other networks. Conclusions and further works are represented in section 6.
2. Information and communication technology (ICT)
Information and communication technology could be regarded as the convergence point of electronic, Information processing and communication. This has two aspects: first, removing distances by linking isolated computers to worldwide network. Second new capacities on multimedia transmission based on computerized far communication systems. This technology is a combination of various sets of data and information technology tools and resources to publish, save and manage them. Using this makes information, products, people and capital efficient flows beyond local, regional and national area limitations [1].
Incoming computer, internet, wired and wireless communication technologies along with powerful text, voice and image processing softwares in electronic devices make new and modern ICT. New form of this technology has received a serious attention since 1980. UK government called the year 1982 as "Information Technology"; also UN called the year 1983 as "World Communication" [2].
Some researchers pointed out the negative impacts of automation and remote works; but others focus on technology positive impacts because of reducing geographical distances and making an idle state of decentralized.
On the other hand, long distances between financial, administrative, commercial and industrial centers and rural areas also equipment centralization in cities cause outland zones people depauperation and migration to larger population centers specially cities. This means larger centralization and citizenship and negative rural development. Furthermore communication and other intelligent networks and ICT equipments in cities make them more interesting for life. Main goals of ICT development are:
• Avocation and economic growth beside decentralization.
• Better quality of service by rivalry growth and remote works.
• Having better life and increasing human abilities.
• National identity and power revival.
According to this, ICT development in rural areas stands on top of governments’
programs. There exist a lot of ICT developed successful instances all around the world especially in not developed countries [2-6]:
• The best instance in this field is India: a large country with poor people especially in rural areas. Indian government developed telephone networks in rural areas to move toward the information societies in those places. Rural information kiosks are a part of this project. Autonomies, new and permanent societies are the goal of Indian government rural IT development. Pakistan government has started a similar plan.
• The other successful instance is Egyptian government "TACCS" project in 1998.
Conducting this project, internet users in Sharkeya outland zone grew to 6000 people.
Other Arab governments like Jordan, Lebanon and Sudan have similar project based on this successful experience.
• Bangladesh government has preferred internet wireless communications centers.
Government did rural IT development project named "Grameen Phone". In this project, people and specially women take a loan to buy mobile phones and government sets up information kiosks in rural areas.
• In Malaysia, government has started developing internet buses in "MIU" project. These buses use VSAT satellite links and they are to make rural people and specially students familiar with internet.
• "Shahkooh" and "Gharn Abad" are two successful rural ICT development examples in Iran. Iranian government in a spread project has given each villager at least one phone
line in order to pay attention to wireless and mobile phone communication infrastructure development.
• Among rich Asian countries, South Korea has experienced a good ICT development.
Since second half of 1960s, Korean government tried to reduce digital gap between Korea and developed countries through communication infrastructures and IT development. In 1996, Mobile phone project started.
• PEOLPLink nonprofit institute is a combination of 22 less developed countries’ artisans.
In this institute, artisans learn instructions through multimedia instructions. Artisans' products are sold via institute web site ultimately.
Table 1: today applications bandwidth requests
Application Bandwidth
Instant messaging <0.25 Kbps Personal communication 0.3 Kbps to 9.6 Kbps
E-Mail 2.4 Kbps to 9.6 Kbps
Remote control programs 9.6 Kbps to 56 Kbps
Digital phone 64 Kbps
Interactive games 50 Kbps to 85 Kbps
VoIP 4 Kbps to 64 Kbps
Music/speech 5 Kbps to 128 Kbps
Video phone 32 Kbps to 384 Kbps
Video clips 20 Kbps to 384 Kbps
Bulk data or movie download >1 Mbps Database text access <1 Mbps
Digital voice 1 Mbps to 2 Mbps
Movies streaming >2 Mbps
Access images 1 Mbps to 8 Mbps
Compressed images 2 Mbps to 10 Mbps Medicine correspondence <50 Mbps
Table 1 shows today applications bandwidth requests. With growing user units and multimedia services, poor band telephone lines can't support new band width requirements.
This situation forces governments to replace primary infrastructures with wide bands ones.
South Korea is good instance in this area. In 2004, wide band users in this country were 4 times more than US, 9 times more than Japan and 70 times more than UK wide band users.
This process can be clarified based on the fast development of Korea in last 3 decades form a poor country to a rich country.
Because of rural low literacy level and their poor internet and IT use abilities, rural wide band communication links are much important. Far multimedia communications are bases for rural people movement to the information society. Wireless networks among wide band communication structure are going to gain a special place. European growths of teleworking diagram shows that in 2010, half of the far distance activities in this mainland are based on wireless networks [7].
3. Wide band networks types
High speed wide band infrastructures networks shall be divided into two main subcategories:
wired infrastructures against wireless infrastructures.
3.1 – Wired infrastructures
Wired wide band infrastructure types are:
• T1/E1 based networks.
• SONET and SDH networks.
• Frame relay services based on fibre or E1/T1.
• Ethernet data services based on fibre optic.
• Fibre optic IP data services.
• ATM services on active/inactive fibre.
• Wave length services on mix coaxial fibre.
• xDSL lines.
• ISDN lines.
These category standards are due to last century. For example T1/E1 based standard was introduced in 1960s, whereas Frame relay standard was developed in first half of 1990s.
T1/E1, xDSL and Frame relay networks are more demanding choices for small and middle size areas wide band network developments [8].
Customers can use Leased line infrastructures as an internet fixed broadband access method. With these lines, they have 24 hours customized line. Table 2 shows Leased line carriers in the world. Among these carriers, E1 and T1 are used widely. T1 in North American and E1 in other countries are used for this purpose.
Table 2: Leased line carriers
T- Carrier E- Carrier
Digital Signal Level T service carrier Bandwidth E service carrier Bandwidth
DS-0 DS-0 64 Kbps DS-0 64 Kbps
DS–1 T1 1.544 Mbps E1 2.048 Mbps
DS–1C T1C 3.152 Mbps NA* NA*
DS–2 T2 6.312 Mbps E2 8.448 Mbps
DS–3 T3 44.736 Mbps E3 34.368 Mbps
DS–4 T4 274.176 Mbps E4 139.264
Mbps
* Not Available
DSL is the last technology in the cable modem products that provide 64 Kbps to 50 Mbps speed on the twisted pair cables. DSL modems can work with analog and digital telephone carriers. ADSL2+ is the last DSL family member that has been presented in 2003 by ITU.
This can work with 2.2 MHz (two times ADSL2).
Main problem with such subcategories is cabling. Cabling in some areas like highland areas is too hard and costly. In addition, cable and other middleware equipments like routers and amplifiers maintenance cost, beside other overhead costs such as renting or buying office and furniture, security policies, electricity and other hardware and software equipments costs have negative impacts on this category developments.
3.2 - Wireless infrastructures
Most wide band wireless standards are under developments or are newly published. Some of this category instances are:
• Wireless metropolitan area networks (IEEE 802.16 standard or WiMAX).
• Full area coverage range satellite networks.
• IEEE 802.20 (MBWA)
• ITU 3G
Under development IEEE 802.20 standard (MBWA) which is known as mobile wide band technology, too. This standard goal is high speed mobile networks. ITU mobile data services 3G that are defined as high speed wireless connections. This generation has a cellular structure and its goal is wireless wide geographical spread voice and internet communications and connections.
Wireless economical usage reasons are:
• Low cost wireless equipments ownership because of reducing cabling costs.
• Network scalability regardless of reserved and added customers because of central network management software and much based station management.
• Customer's concentration and network connection abilities from every wave cover range location.
• Easy, fast and low cost network connection.
• Large cover service sets like VPN, IP telephone, circuit telephone, video conference and etc.
• High speed service delivery.
• Network turnover with respect to the service suppliers.
4. Wireless Metropolitan Area Networks
Standard IEEE 802.16 can be used for wireless metropolitan area network construction with accessing network from building inside to the Base Stations (BS) through external antennas.
Wireless metropolitan area network is an option to replace traditional cabling network like fiber optic connections, coaxial systems with cable modems and DSL lines. It predicts 1 billion dollars with 2 to 4 million user market for this standard in 2008 [9].
WiMAX objectives are flexible architecture, high security, QoS, quick deployment, multi level service, interoperability, portability, mobility, cost effective, wide coverage, LOS and NLOS and high capacity and speed. WiMAX can be used on cellular and WSP backhaul, public safety, banking and education networks, offshore communications, rural and campus connectivity, WSP access network and temporary constructions like military battlefield.
Fig. 1: IEEE 802.16 structure
4.1 - PHY and MAC layer
IEEE 802.16 standard is designed to entail a set of air interfaces with common MAC protocol and proportionate physical layer (PHY) with radio frequency wave length laws on each zone.
The year 2001 primarily presented standard work with 10 to 66 GHz frequencies that were available in all areas around the world. New problems on short wave length force WiMAX to use low frequencies range from 2 to 11 GHz. With this licensed \ unlicensed range, users can access to network with low cost and speed and WiMAX can be available in small and middle size areas.
In 10-66 GHz PHY design, line of sight (LOS) propagation is a special need. This plan aggregates with ATM and IP protocols and produces 30 miles covering range services. MAC layer is optimized for long and variable delays. WiMAX equipments use time division duplexing (TDD) on unlicensed frequency bands and frequency division duplexing (FDD) on licensed frequency bands [10]. 2-11 GHz licensed/unlicensed band are introduced in IEEE 802.16a. This PHY planned to use non line of sight (NLOS). NLOS can operate on low frequencies and don't access on high frequencies. Preventive like trees cause that home applications not be on sight of BS antennas. In addition, outdoor antennas have more equipment and installation costs. Therefore NLOS has more interested [11]. To keep high
efficiency with NLOS support, Orthogonal Frequency Division Multiplexing (OFDM) signaling is superior to Code Division Multiple Access (CDMA) that used in 2G and 3G [12].
WiMAX radio link control plan uses uplink and downlink profiles. These profiles contain communication patterns. This method causes a robustness radio link control. Also WiMAX uses Adaptive Modulation and variable error correction encoding per RF burst to ensure a robust RF link while maximizing the number of bits per second for each subscriber unit. In the bad air conditions like rain, this enforces subscriber stations to use robust profiles and in the good weather, they can use efficient profiles.
Wireless nature of WiMAX forces it using security mechanism on its MAC. WiMAX Mac layer use X.509 digital certificate, RSA public and private keys, data encryption standard (DES), cipher block chaining (CBC) and hashed message authentication code protocol (HMAC) to protect user's data.
WiMAX can provide QoS with 4 services categories:
• Unsolicited grant per services (UGS) for support real-time data streams consisting of fixed-size data packets issued at periodic intervals, such as T1/E1 and Voice over IP.
• Real time polling service (rtPS) for supporting real-time data streams consisting of variable-sized data packets that are issued at periodic intervals, such as MPEG video.
• Non real time polling service (nrtPS) for supporting delay-tolerant data streams consisting of variable-sized data packets for which a minimum data rate is required, such as FTP.
• Best effort (BE) for support data streams for which no minimum service level is required and which can be handled on a space-available basis.
4.2 - Mesh mode
IEEE 802.16 MAC protocol supports two modes: Point to Multipoint (PMP) and Multipoint to Multipoint (Mesh) mode. PMP mode is used in IEEE 802.16 basic structures. In this mode network has a cellular structure and is composed of one BS and some Subscriber Stations (SS). Uplink and downlink channel is shared between all SSs. In PMP mode all SSs must be on BS RF covering range and its line of sight.
Mesh mode is a new way to give wide band access to home users and SOHO [13]. In mesh mode, all stations can use direct communications with each other without using BS.
There are three node types in this mode: Mesh BS (MBS) that operates as a group manager and create connections to out of mesh network and Mesh SS (MSS). All SSs in cells communicate with cell's MBS and for outside network access, MBSs should communicate with central MBS. Only this MBS can communicate without world network. Using intelligent routing protocol, WiMAX mesh mode can transmit data with the best quality on the best possible way.
Hexagonal cells are the best choice for mesh structure [14]. With this, each cell can have up to six neighborhoods. Some mesh cluster topologies are given with at most two hops from central MBS. [10] supposed 1 mile radius cells and 900 miles square covered with different mesh topologies. Results show that usage of larger topologies causes reduces central MBSs and cabling costs. User units growing in each cell need more band width and data processing and therefore have a negative impact on network cost. It recommends that use mesh mode only for small and middle size areas with normal user units.
5. Compare wireless metropolitan area network with other wide band networks
Here, we compare IEEE 802.16 network with DSL, T1/E1, MBWA and 3G regarding performance, covering range, movement, reliability, security options and rental cost per month. Comparison results are shown in tables 3, 4 and 5.
Table 3: Performance comparisons
Network Bandwidth Max bit rate
WiMAX 70 Mbps at 14 MHz
>5 MHz 155 Mbps
MBWA
3.2 Mbps at 1.25 MHz (downlink) 16 Mbps at 5 MHz (uplink)
<5 MHz 16 Mbps
3G <2 Mbps (typically 300- 600 Kbps)
<5 MHz 2 Mbps
DSL 51.84 51.84 Mbps (downlink) 3 Mbps (uplink) Mbps
T1/E1 2.048 Mbps 2.048 Mbps
Comparison results in table 3 show that WiMAX produces largest bandwidth against other networks. Even DSL and T1/E1 wire networks can't produce this bit rate. In other hand WiMAX maximum bit rate is larger than MBWA, 3G, DSL and T1/E1 networks.
Table 4: Covering and movement
Network Range Movement LOS /NLOS
WiMAX Up to 30 miles (LOS)
Up to 5 miles (NLOS) <75-93 mph NLOS LOS
MBWA Up to 9 miles <155 mph NLOS
3G Typically 1-5 miles
310 mph at 144 Kbps 75 mph at 384 Kbps
6 mph at 2 Mbps NLOS
DSL 2 miles Static network Direct wired links
T1/E1 3 miles Static network Direct wired links
Table 4 shows that WiMAX produces largest radius coverage against other networks.
Also it shows that other wireless network can cover larger area against wire networks. Under draft MBWA standard can covers up to 9 miles and 3G can covers up 5 to miles, but at the best conditions DSL can services 2 miles and T1/E1 can services 3 miles. Even MBWA and 3G wireless networks can't produce such With LOS/NLOS support; it is a confident and robust network to serve users.
Wireless networks have LOS/NLOS access methods. These methods are a confident and make a robust network to serve users. WiMAX can support both of these. WiMAX uses 256 point FFT OFDM waveform to addressing multipath in outdoor LOS and NLOS environments.
Because of wireless nature of WiMAX, MBWA and 3G, they need built in security features that make them a confident network to serve users. Wire networks use upper layers security protocols or external security hardwares and softwares.
Table 5: Security and cost
Network Security Rental cost Per month
WiMAX Built in standard 1300$ (34 Mbps) 2500 (155 Mbps) For 10 km users length
MBWA Built in standard NA*
3G Based on GSM with enhancements 15-30$ per month DSL Based on external software and hardware 20-30$ per month T1/E1 Based on external software and hardware 400$ per month
* Not Available
In rental cost per month column, we don't insert install and maintenance costs and times. For 10 kilometer users' length, we don't need to middleware equipments in WIMAX. But in other schemes we need middlewares. This increases infrastructure developing costs and therefore rental costs. On the other hand, WiMAX wide bandwidth can be distributed between many
users, low rental cost. For example with 1 Mbps users, each user should pay 40$ in 34 Mbps scheme and 16$ in 155 Mbps scheme.
WiMAX smart antennas are fast becoming more affordable and as these costs come down their ability to suppress interference and increase system gain will become important to BWA deployments.
6. Conclusions
Daily ICT development makes mass improvement and evaluation on today human life.
Robust technology preference force governments forget negative technology preference and try to fast ICT development. Infrastructure development is a basic provision for this proposition.
Regardless of some positive wired network preference, today's trend is to wireless network structures. Wireless structure, preference and problems of researches and comparison results show superior wireless technologies on usage cost and performance. Future work can be on area outside and weather impacts on wireless signalling.
7. References
[1] Marzeye Noori, "ICT and rural depauperation", the proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 9-18, 2004.
[2] Hossein Barani, Raee Ghodsi, "scare and hope on rural area ICT development", The proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 3-8, 2004.
[3] Mojgan Abasi, "ICT impact on reducing rural migrations", the proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 61-67, 2004.
[4] Farsheed Aghadavoodi, Mohammad Jafar Sedeegh, Khosro Saljoghi, "rural IT center plan", The proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 69-77, 2004.
[5] Ali Akbar Jalali, Mohsen Abasi, Sara Gorganinejad, "South Korea rural ICT", The proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 95-102, 2004.
[6] Ali Khosravi, "ICT on agronomy and rural development", the proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 123-131, 2004.
[7] Jalali, Hossein, Jalali, Amir H., "Teleworking and its impact in the rural areas", the proceeding of the Iranian conference on information and communication technology for rural areas- RITC 2004, pp 153-158, 2004.
[8] Daniel Sweeney, "WiMAX operator's manual, Building 802.16 wireless networks (second edition)", Apress, 2006.
[9] Alan Barry, George Healy, Cian Daly, Joseph Johnson, Ronan J. Skehill, "Overview of WiMAX IEEE 802.16", Fiveth Annual ICT Information Technology and Telecommunications, Cork, October 2005.
[10] Vinoth Gunasekaran, "Affordable infrastructure for deploying WiMAX systems: Mesh v. Non Mesh", 62nd IEEE Vehicular Technology Conference, Dallas, 2005.
[11] Carl Eklund, Roger B. Marks, Kenneth L. Standwood, Stanley Wang , “IEEE standard 802.16: A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Access” , pp. 98–
107, IEEE Comm. Magazine, vol. 40, no. 6, June 2002.
[12] "IEEE 802.16a Standard and WiMAX Igniting Broadband Wireless Access, White Paper", Worldwide Interoperability for Microwave Access Forum, 2 September 2003.
[13] Jianfeng Chen,Wenhua Jiao, Qian Guo, "An integrated QoS control architecture for IEEE 802.16 broadband wireless access systems", IEEE Global Telecommunications Conference, 2005.
[14] Ian F. Akyyildiz, Xudong Wang, Weilin Wang, "Wireless mesh networks: a survey", Scinence Direct Magezine, Volume 47, Issue 4, pp 445-487, 15 March 2005.
