Wireless Communications and Mobile Technology

Wireless LAN technology is gaining broad acceptance and being adopted world-wide in organizations that clamor for competitive advantage of an increasingly mobile and highly productive  workforce. The WAP 2000 series access point, which  sets the enterprise standard  for  secure, manageable  and reliable  wireless  LANs  while  also providing a smooth migration path to future high-speed wireless LAN technologies. This innovative, state-of-the art wireless  infrastructure  platform features dual-band functionality that simultaneously supports  current and  emerging  wireless  standards.One of the most innovative aspects of the WAP 2000 series access point is that it is both software and hardware  upgrade  their software  to  take  advantage  of  new  features  that  DAX will develop in the future, but they also will be able to  upgrade the radios in the field to take advantage of new high-speed wireless standards.

WIMAX (world-wide interoperability for microwave access) is the IEEE 802.16 standards based wireless technology that  provides MAN (metropolitan area network) broad band  connectivity. WIMAX can offer a solution to what is  normally called the“last-ile”problem by connecting individual homes and business offices Communications. It is to be  less  expensive  than their  wired counterparts,such as digital  subscriber  lines (DSL).  This will  now  be  able  to  enjoy high-speed internet access since distance up to  30miles (50km) are supported.

“No wires, No rules”. Zooming down the highway, you will be able to use a laptop or PDA to check the weather or traffic a few miles ahead. From physical issues up to applications aspects, Mobile Ad hoc networking in Wi-Fi (wireless-fidelity) comprehensively covers all areas of the technology including protocols and models with an emphasis  on the most current research and development. To understand wireless technology trends and to see why non infrastructure-based  Mobile Ad hoc networks are poised to play an important role in the evolution of future wireless networks. It helps in the evolution path of different technology generations.

1.0 INTRODUCTION:

Wireless technology for computer users is nothing new. The first connections were established two decades ago. Adoption, though, has proceeded very slowly, mostly limited to a few specialized vertical markets, such as warehousing, education and retail.

Implementation has been slow for three reasons.first, the original wireless data rates were  too slow to serve  mainstream  users on a shared LAN. Although throughput did gradually increase, network speeds still drastically lagged those of wired  LANs.  Second,  proprietary, nonstandard  solutions  dominated  the marketplace, providing little interoperability  among devices, or the  peace of  mind for  users that come from  having multiple vendor options.third, these low speed proprietary solutions were very expensive compared to wired solutions.

In recent years, the situation has changed dramatically. In 1999, institute of Electrical and  Electronics Engineers(IEEE) ratified the 802.11b standard, offering data rates up to 11 megabits per second (mbps),similar to the 10 mbps connections that are common for  many Ethernet-based work groups. For the first time, wireless LANs became truly usable for most work environments and office applications.  Multiple vendors quickly came to support  the  802.11b  standard.  This  rapidly  drove down  costs, leading  to  increased demand and even greater vendor support.  In addition, the 802.11bstandard assured users of device interoperability. The Wireless Ethernet Compatibility of wireless  LAN  products based on the IEEE 802.11b specification and to promote the use of the standard across all  Market segments. With the rapid adoptions of the 802.11b standard,  users  began to have a choice of a  wide variety of  interoperable, low-cost, high –performance wireless equipment.

Perhaps most importantly, much type of organizations today sees tremendous value by adding wireless on to the corporate LAN. For years,  laptop and notebook computer shave  Promised  anytime,  any where  computing.But, with access to the  LAN  and the internet becoming such an integral part of business,  a wireless  connection  is  needed  to make true the  Promise of anytime, anywhere computing. Wireless devices enable users to be constantly connected from virtually anywhere: a desk, a conference room,  the coffee  shop, or another  Building on a corporate or academic campus. This ability provides users with maximum  flexibility, productivity and efficiency, while dramatically boosting collaboration and cooperation with colleagues, business partners and customers. In addition, wireless can bring LAN access to location where laying cable is difficult or expensive.

1.1 WiMax Standards

This figure shows how 802.16 broadband wireless systems have evolved over time. This diagram shows that the original 802.16 specification defined fixed broadband wireless service that operates in the 10-66 GHz frequency band. To provide wireless broadband service in lower frequency range, the 802.16A specification was created that operates in the 2-11 GHz frequency band. To provide both fixed and mobile service, the 802.16E specification was developed

Both 802.11a and 802.11g offer substantial improvements over the current 802 . 11b  standard, Because higher data rates deliver far greater performance and usability for devices on the wireless LAN.The one disadvantage is that the802.11aand 802.11g standards are not compatible because they use different frequency bands. further more, 802 11a is not compatible with the exiting installed base of 802.11b devices.
So, what should organizations do? This decision is critical as look a head to the future of their wireless infrastructure. it will guide their product choices and infrastructure capabilities for years to come.

2. Wimax: Broadband wireless access technology

wimax  is  a  wireless standards  developed by working group  of  institute of electrical And electronics engineers (IEEE). The first version, IEEE 802.16 activities were initiated by the national wireless electronics systems tested (N-WEST) of the u.s national institute of standards and technology.

The WIMAX from is a non-profit group that promotes 802.16 technology and certificates  compatibility and interoperability of broadband wireless access equipment that conforms to IEEE 80 2.16 & ETSIHIPERMAN standards. That standard offers an alternative [1] to cabled  access  networks, such as fiber  optic  links, coaxial  system using cable modems, and digital subscriber line (DSL) links or t1 links. This technology provides fast services, flexible, cost effective filling of the existing gaps of wired network and facility to create new services.
The IEEE has  established  many  wireless  standards  as  IEEE  802.15  for personal Area network (PAN), IEEE802.11  for local  area  network  (LAN),  IEEE802.16 for  local  area network (LAN), IEEE802.16  for  metropolitan  Area  network  (MAN).  Each standards represents the optimized technology for usage model.

2.1 – Typical WLAN Roaming

The topology of roaming cells may take on many forms but the essential building block is a collection of wireless devices with overlapping BSS. The overlapping wireless roaming cells mainly constitute an Access Point to Access Point (AP-to-AP) signal, Access Point-to-Wireless Client (AP-to-WC) linkage, or Wireless Client-to-Wireless Client (WC-to-WC) association. In a typical WLAN topology, the WC does not communicate directly with each other; they communicate with the access point. If a single BSS does not provide enough coverage, a number of wireless cells can be added to extend the range. (ESS).

One form of Wi-Fi™ Mesh comprise of a collection Root-AP overlapping to create wireless roaming cells.