by August 4, 2004 0 comments



Solutions for wireless LANs, WANs and wireless Internet are many, but you need to decide which works the best for you. Copper and fiber technologies for data communication have evolved significantly and are continuing to do so for quick and efficient data transmission. However, there are conditions where wired data communication solutions cannot meet the requirements, doesn’t make economic sense, offer less convenience, are difficult to set up or are not present at all. For such conditions going wireless is the solution. 

But just as there are various wire line solutions, there are various wireless solutions as well, using different technologies, suited for different purposes, carrying their set of advantages and disadvantages. 

So, before you head anywhere, there is a need to know the various wireless options that you can choose from, functions they provide, advantages and disadvantages they have, their suitability for a particular purpose and tips for buying a particular solution. Also, it is not about choosing the right wireless product alone, but also about choosing the right solution and implementing it,
which also brings in picture the network integrators and/or service providers. 

To help you in making a wise decision, we give you detailed insights on wireless technology, products and implementation.

Indoor and Outdoor Wireless LAN (WLAN) 
The default technologies for building wireless LANs are based on the different versions of the IEEE 802.11 standard, namely 802.11b, ‘g’ and ‘a’, which are more commonly called WiFi as a catch-all term for WLAN. 802.11b operates on the 2.4 GHz frequency band and offers a theoretical maximum throughput of 11 Mbits/s. 802.11g and 802.11a provide a maximum throughput of 54 Mbits/s and operate on 2.4 GHz and 5 GHz band, respectively. Although WiFi products do not require line of sight, throughputs vary due to obstructions between the WiFi access point (AP) and the wireless user, the distance of the user from the AP and the number of users connected to an AP. Out of ‘a’, ‘b’ and ‘g’, 802.11b has been most widely used, but 802.11g with its backward compatibility with 802.11b is the one you should be looking for. The price difference between ‘b’ and ‘g’ is also decreasing rapidly.

Microwave Radio:
Microwave radio is the predominant technology for private wireless WANs and offers good throughputs and range. However, there is less standardization on the technology front leading to incompatibilities between products from different vendors
Free Space Optics: Free Space Optics, which uses laser to transmit data is a niche wireless solution. It offers very high speeds and has a range of few kilometers.

Compared to Microwave radio, it is easier to install and is a good option for temporary, make-shift communication requirements

VSAT: VSAT can provide connectivity to the remotest locations of the world. Is ideal for providing connectivity to rural and hilly areas. With few points of failure, is also a good option for disaster recovery centers
WiFi: WiFi, especially 802.11b, has been very successful for building wireless LANs. With prices falling for 802.11g products, you should be looking at it. However, government clearance is still required for ‘g’. Appeal to the government to deregulate the ‘g’ standard like it did for ‘b’

Range
Indoor WiFi products using standard antennae typically have an operating range of up to 100 meters when used indoors, and 100-400 meters when used in open. However, the range of this equipment can be increased by using special antennae, ensuring line of sight and by using wireless repeaters. Few products also provide a range of 5-8 kilometers, which is achieved by increasing the power levels of transmitting signals and using special antennae. But government regulations govern the deployment of WiFi. Till date, only 802.11b can be set up without government permission within the campus. For WiFi signals to go across the campus or building, government license is required. Similarly to use 802.11g or ‘a’, within or outside the campus, government clearance is required.

Security, QoS and Manageability 
Unlike wired networks, where physical access to the wire is required to prone, wireless networks are more open for attacks because anyone can listen into the signals traveling in the air. The built-in security method in WiFi called WEP is also flawed and can be easily overcome. However, there are many other solutions for securing wireless networks such as the Remote Authentication Dial-In User Service (RADIUS) protocol and Point-to-Point Tunneling Protocol (PPTP) VPN, which offer end-to-end encryption over WiFi networks. But not all products provide these security options and still use WEP. Recently, IEEE has formally approved the long-awaited 802.11i extension to the 802.11 wireless LAN standards for more robust security. Products based on the standard may start appearing by this year-end. Most portions of 802.11i, informally known as WPA (WiFi Protected Access), are already at work in some products.

Managing a WLAN can become a challenge as the number of users and APs increase. Ideally, an enterprise should be able to manage the WLAN the way it manages the wired LAN, that is both kinds of networks should be manageable from the same platform. The WLAN that you build should also support QoS, wherein you can prioritize voice, data and video traffic.
To choose the right WiFi product you can check out the WiFi AP shootout we did (page 132, PCQuest, May 2004).

WLAN Implementation
Selecting of the right WiFi equipment is only half the work done. Radio survey, network survey and proper design are also important for successful implementation. Radio survey helps in designing the network better and in ensuring that the signals don’t interfere with other wireless networks in and around the site. It also lets you know whether the signals are crossing the defined limits for the WLAN. Site survey is important because obstructions like walls and other physical objects limit the range and throughput of WLAN. So the network should be designed in such a way that APs are strategically placed so as to overcome all physical barriers both within and outside the building. Site survey also helps in deciding the number of APs required at the premise. 

A WLAN should be scalable to add more users and APs in the future. Compatibility of the WLAN with the existing network and interoperability of APs and wireless cards from different vendors are also important considerations.

Microwave Radio for WAN or Internet
Microwave radio or terrestrial wireless can be used to build wireless WANs, and by ISPs, to provide wireless broadband Internet services. Microwave is especially useful in cases where laying wires is not possible or is less economical, such as in rural or tough terrain areas. Microwave wireless systems work in the 900 MHz to 40 GHz frequency band. Higher frequencies carry far more data but cannot travel as far as lower frequencies, often requiring line of sight. Higher frequencies also require more complex equipment that can be more expensive. Lower frequencies on the other hand, travel further and are cheaper, but cannot transmit large amounts of data. The range varies from 2-3 kilometers to more than 50 kilometers depending on the frequency used, power of the signals and line of sight conditions. Microwave systems can be used in a point-to-point (P-T-P) or point-to-multipoint (P-T-M) configurations. P-T-P can be used to connect two very far off office locations and P-T-M is useful for connecting several offices or for providing wireless Internet services to subscribers. Data transfer rates provided start from few Mbits/sec and can go up to few
Gbits/sec.

WiFi vendors FSO vendors
Cisco, D-link,
Dax, Compex
AT&T, fSONA, LightPointe
Microwave Radio vendors VSAT Vendors
Alcatel, Cisco,
Fresnel, HNS, Proxim, Wi-Lan
HNS, Gilat,
Viasat, NDSatcom
Network Integrators VSAT Service providers
Datacraft, Wipro
Infotech, Tulip, GTL, CMC, HCL Infosystems
HCL Comnet, HECL, Bharti Broadband, Tata Net, Comsat Max, ITI

Free Space Optics (FSO) 
FSO uses laser technology to provide wireless data communication between two points. It imposes strict line of sight limitation between the connecting points. FSO throughputs start from 100 mbps and go up to Gigabit and can cover a few kilometers. Laser-data communication is affected by atmospheric disturbances such as humidity and fog, temporary interruptions like birds flying through the beam.

VSAT
Satellite can provide Internet access to the remotest parts of the world. But they offer relatively lesser bandwidth, higher latency and poorer signal quality. High latency makes them inappropriate for voice and video applications. However, VSATs provide a good solution for disaster-recovery centers, as they are more reliable with fewer points of failure.

COMING UP



Surely WiFi has got wide market acceptance with falling hardware prices, standardization of technology and ease of set up.

Microwave radio is becoming a lucrative option for many enterprises, especially banks, which are looking to build private wireless WANs, but still there is less standardization on the technology front leading to interoperability problems between products from different vendors.

VSAT is a good option for rural areas, where there is no other medium present. It also is a good solution for disaster recovery centers and ATMs.

Free Space Optics, which uses laser beams, is a quick and easy way to connect but has its own set of problems as a long-term solution

IN BRIEF




With little or no standardization present on the Microwave radio front, a new standard 802.16, also called WiMAX is being finalized for building wireless broadband MANs to provide Internet services to both end users as well as enterprises.

WiMAX products are expected by the mid of 2005. But the wireless microwave ISP market has never picked up in India and WiMAX may also not be able to easily substitute existing microwave products for building private
WANs.

A good thing has happened recently for the WiFi security issue. IEEE has formally approved the long-awaited 802.11i extension to the 802.11 wireless LAN standards for more robust security. The WiFi alliance is expected to begin vendor product certification testing in September.

VSAT providers are now not only looking at being service providers, but also integrated service providers giving managed solutions, which is a good sign for disaster-recovery centers

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