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From a technology point of view, newer frequency bands have been opened up in the 802.11 standard. WLAN technologies will soon see the emergence of 802.11n.

802.11n should, in theory, be up to 40 times faster than 802.11b, and almost 10 times faster than 802.11a or 802.11g.

802.11r is the unapproved IEEE 802.11 standard that specifies fast BSS (“Basic Service Set”) transitions. This will permit connectivity aboard vehicles in motion, with fast handoffs from one base station to another managed in a seamless manner. Handoffs are supported under the “a”, “b” and “g” implementations, but only for data. The handover delay is too long to support applications like voice and video.

	EXPERTS PANEL
	Ranajoy Punja, VP-marketing (India and Saarc), Cisco Systems Shridhar Kadam, VP (product engineering), D-Link India

The primary application currently envisioned for the 802.11r standard is VOIP (“voice over IP”, or Internet-based telephony) via mobile phones designed to work with wireless Internet networks, instead of (or in addition to) standard cellular networks.

802.11e as of July 2005 is a draft standard that defines a set of quality of service enhancements for LAN applications, in particular the 802.11 Wi-Fi standard. The standard is considered of critical importance for delay-sensitive applications, such as Voice over Wireless IP and Streaming Multimedia.

TIPS

• Regulatory Guidelines: The government has de-licensed the 2.4 GHz spectrum (specifically, the 2.40-2.48 GHz band) and allowed the indoor or in campus as well as outdoor use of 802.11b and g within the band. In January 2005, the government exempted the “Indoor Use of low power wireless equipment in the frequency band 5 GHz” from licensing requirement.

• Radio Survey: It must carry out a radio survey of the area it wants its WLAN to cover. A survey is important for two reasons: one, it would help an enterprise design its network better and two, it would ensure that one network's signal does not interfere with other networks in and around the proposed deployment site. An enterprise must ensure that radio signals do not cross the defined limits within which it wants the WLAN to work.

• Site Survey & Network Design: Once the radio survey is done, the other important consideration should be the interior design structure of the site where WLAN is going to be set up. WLAN systems use RF. And the distance over which RF waves can travel is not the function of the product alone. It also depends on the propagation path of RF. Even though RF waves are capable of penetrating most indoor walls and other physical obstacles, their range of coverage surely depends on the indoor architecture of the building. In open spaces each wireless LAN access hub can cover up to 300 feet, while in places with physical barriers-like walls, a hub could be effective in the range of 130 feet only. This would naturally mean that access points are placed strategically as such to overcome all physical barriers inside the building. Otherwise users would not be able to enjoy the advantage of mobility or roam around freely in a building with their connected laptops. The enterprise should get the site survey conducted for verifying the coverage and estimating the number of wireless LAN access points required at the premise. This would depend on the topology of the location and the amount of throughput required.

• An enterprise must also ask itself this question: Why does it need WLAN? In other words it must know why it is deploying WLAN. WLAN can be more beneficial and productive if it is being deployed for running applications rather than just plain mobile Internet access within the enterprise campus. Also, if an enterprise knows beforehand what it is going to do with WLAN, it would be in a better position to calculate ROI on WLAN.

• Integration with existing LAN: How an enterprise integrates WLAN with the existing wired LAN is very important. The integration should be such that it facilitates seamless movement of a user from WLAN to wired LAN and vice a versa. Also, services should be enabled on the WLAN in the same way as they have been on the wired LAN.

Memory Bytes

One of the key factors that need to be kept in mind while deploying a wireless network is to ensure that the customers can take advantage of existing network infrastructure and securely extend access to employees whether they are at work, at home, or on the road. Successfully implementing a secure enterprise mobility solution can help customers increase employee productivity, improve responsiveness to their end customers, and collaborate more efficiently and effectively to deliver integrated mobility solution for data, voice, and video that results in a lower total cost of ownership. For efficiently planning, designing, implementing, operating, and optimizing a wireless solution within an enterprise, follow a process: The Presale Phase: Making customers understand the business, technical, physical infrastructure, and financial requirements for implementing a wireless solution before making a purchase decision. The Plan Phase: Prioritize customer requirements by planning wireless component placement, wireless network security, as well as performance, and scalability. At this phase Cisco helps the customer determine which products and technologies will best meet their needs, how devices should interoperate, and how devices will impact the network. Design: By now a Wireless plan has been established and an initial solution incorporating customer specific infrastructure considerations has been developed. In the design phase, the project team focuses on developing the low-level design that will be followed during the implementation phase. The team reviews the design and presents the final low-level design to the customer for acceptance.   At this stage, the project team makes decisions on: • How to meet application, support, back-up, and recovery requirements • Migration strategy, test plans, training plans • Device configurations (parameters and features to turn on or off, and protocols to use).  The team assesses the current state of the network to identify vulnerabilities and gauge the potential impact of the solution that they plan to implement.   Implementation: In this phase, customers need to be cautious about introducing wireless solutions and appliances into the network with the least amount of disruption and highest level of interoperability with existing elements on the network. During the implementation, partners provide project planning, management and communication, staging, installation and configuration of solution elements. They also create and execute test plans to verify that the solution is deployed in accordance with the low-level design. In addition, partners train operations staff and users, and transfer responsibilities to the operations group. The first four steps in the Implement phase (ordering equipment, planning the implementation, monitoring and controlling the project, and preparing the site) must be completed prior to the beginning of implementation of a wireless solution. Operate: In this phase of a wireless solution, customers need to ensure that products operate efficiently and remain highly available. This phase includes activities such as monitoring the service of the network. It also includes detecting and resolving any service disruptions in the wireless network, as well as upgrading components as needed. Optimize: Once the wireless solution is up and running, it is important to keep it functioning as efficiently as possible and with high availability, while resolving problems quickly as they arise. Devices must be continually assessed for bandwidth and memory allocation and adjustments must be made to the network as needed.

• Security: Wireless LAN networks have been found prone to unauthorized access, breaking of encryption and loss of data integrity. And except for some of the well-known vendors of WLAN products and solutions, most vendors do not use any accepted security standards. So an enterprise must ensure that it deploys only those WLAN products that adhere to widely accepted and proven security standards.

• QoS: An enterprise must also ensure that any network that it deploys should have QoS built in. Among other things, this should mean that the WLAN must allow an enterprise to prioritize voice, data and video on the network, and the network is scalable.

• Manageability: Managing a WLAN network could be a challenge as the network grows and adds more and more users. As such, an enterprise must look at managing WLAN in the same way it manages its traditional LAN. In other words, it must look at managing both WLAN and wired LAN together from the same platform.

• Throughput: Practically 802.11B does not support more than 5.5 Mbps bandwidth. Moreover, in a multi-user environment, a single user cannot expect to get even this 5.5 Mbps as the bandwidth is shared with other users. Besides, as the user keeps moving away from a wireless LAN access hub, the bandwidth output keeps on decreasing. Naturally, all this rules out high-bandwidth applications. Wireless LAN throughput is sufficient for applications like electronic mail exchange, access to shared peripherals like printers, Internet access, and access to multi-user databases and applications.

Ravi Shekhar Pandey
vadmail@voicendata.com