Toolkit: Tutorial: Comparing Wireless Broadband Technologies for the Enterprise Campus

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Gartner for IT Leaders

Publication Date: 22 September 2006 ID Number: G00143195

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Toolkit: Tutorial: Comparing Wireless Broadband

Technologies for the Enterprise Campus

Robin Simpson

Since early 2005, colleges and universities worldwide have been among the first organizations to deploy large-scale 802.11-based Wi-Fi mesh networks to provide Internet and intranet access for their students and staff. As in business, the laptop has become an important student tool in many educational institutions, with applications including online access to course materials and research, audio and video streaming of lectures and tutorials, distribution and submission of assignments via e-mail, and

collaboration among students and staff. However, as in business, voice remains the No. 1 mobile application for personal and academic use. Because most students today arrive on campus with their own mobile phone, some institutions have also begun to provide infrastructure to improve cellular coverage in-building and across the campus.

The same technologies can be applied to almost any kind of large business or government precinct with outdoor and indoor areas — from head offices or factory complexes to shopping malls, city halls and airports.

Key Findings

• Businesses face the same mobile application, work-style and infrastructure issues as colleges and universities, so they should study the campus wireless network design and deployment lessons learned by those institutions.

• A single network technology — fixed or wireless — cannot satisfy all campus mobile connectivity needs. A hybrid network will be required for the foreseeable future. • Enterprises should consider partnerships with public infrastructure operators for

large-area campus deployments to minimize capital and operational costs — especially for voice services.

• Enterprises that own or control their buildings and campus surroundings have two things every wireless operator wants: real estate for antennas and base stations, and right of way for backhaul — two valuable commodities when building a wireless network.

Predictions

• WiMAX will not be a viable campus Wi-Fi backhaul technology until 2008.

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Recommendations

• Supplement your fixed wireless LAN with a wireless WAN and wireless mesh network strategy for campus mobile broadband.

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ANALYSIS

The Technologies Available for Campus Wireless

Wi-Fi technology conforming to at least the 802.11 b and g standards is built into almost every enterprise laptop today, and an increasing number of enterprise-class PDAs and cell phones, as a low-cost or no-cost option. Thus, from the point of view of the end user at least, it is an ideal low-cost network access technology. However, Wi-Fi is not the only choice for the campus network infrastructure itself, particularly if coverage of a large geographic area is required — Wi-Fi mesh, WiMAX, proprietary wireless broadband access or even 3G cellular networks may all have a place.

Comparing the Available Technologies for Access and Backhaul

Table 1 shows the wireless broadband technologies that can be used for campus deployment.

Table 1. Wireless Broadband Technologies for Campus Deployment

Technology Strengths Weaknesses Future

Fixed Wi-Fi LAN (802.11 a,b,g)

Low-cost consumer premises equipment (CPE) for 802.11b and g — now included in many laptops

PC Card CPE available Low-cost infrastructure Relatively easy and fast to deploy

"Free" industrial, scientific and medical (ISM) band spectrum

Strong standards and very competitive vendor market Ideal for access

Useful for backhaul and bridging.

802.11a good for capacity and channel management High, symmetrical bandwidth

Data usage is free within the campus network

Limited range (100 m) Not very scalable to large networks

No standards-based roaming

No cell-to-cell mobility Limited channels for 802.11b and g

802.11a has channel or licensing issues in some countries

The 2.4GHz ISM band used by 802.11b and g is prone to interference — from other Wi-Fi networks, or from consumer technologies like Zigbee or Bluetooth Battery and processor hungry at higher bandwidths Access point capacity can limit voice capacity

802.11n standard, when agreed, will support greater than 100-Mbps throughput

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Wi-Fi Mesh (802.11 plus proprietary extensions)

Low-cost CPE for 802.11b and g — now included in many laptops

PC Card CPE available Low-cost infrastructure that is highly scalable to large areas

Easy and very fast to deploy

"Free" ISM band spectrum Ideal for access and backhaul

802.11 b, g can be used for access along with 802.11a for mesh backhaul

High, symmetrical bandwidth Data usage free

Proprietary — IEEE 802.11s mesh standard still under development

Single vendor lock-in for supply and support No guarantee that vendors will support eventual 802.11s standard No standards-based roaming

No cell-to-cell mobility The 2.4GHz ISM band used by 802.11b and g is prone to interference — from other Wi-Fi networks, or from consumer technologies like Zigbee or Bluetooth Battery and processor hungry at higher bandwidths Voice performance can be poor because multihop mesh backhaul architecture leads to congestion and latency issues

WiMAX may be used for Wi-Fi Mesh backhaul, with Wi-Fi used for access

802.11 may be overshadowed by WiMAX, at least for backhaul and outdoor coverage of large areas

3G Cellular (wideband code division multiple access [WCDMA] and code division multiple access [CDMA] 1xEVDO)

Wide range of PC Card CPE and mobile terminals available

Increasing numbers of vendors offering laptops with built-in PCI Express 3G CPE

Uses operator-owned infrastructure (no capex) Excellent range (5~20 km) means coverage likely to be better than Wi-Fi Provides high-quality voice as well as data Battery efficient Full mobility, including cell-to-cell handoff at vehicular speeds

Relatively expensive CPE Asymmetric, relatively low bandwidth (300-700 Kbps) Coverage may be limited to high-population-density areas

Requires operator to buy expensive licensed spectrum

Expensive for data usage unless you get a "flat-rate" contract

Even then, "fair-use" data limits may be an issue Premature laptop

obsolescence if not firmware upgradable to High Speed Packet Downlink Access (HSDPA) and High-Speed Uplink Packet Access (HSUPA)

Most PC vendors will include built-in PCI Express 3G CPE The next evolution of 3G called HSDPA will bring data rates of 300-Kbps uplink and 2- to 3-Mbps downlink by 2007 HSUPA will lift uplink speeds to 1 to 2 Mbps by 2009

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Mobile WiMAX

(802.16-2005) 2- to 10-Mbps bandwidth, symmetrical at option of operator

Highly scalable

Base stations much less expensive than cellular or proprietary wireless broadband access (WBA) Excellent range (5 to 20 km)

Very competitive vendor market

Full mobility, including cell-to-cell handoff at vehicular speeds

Ideal for backhaul and for access by 2008

No mobile CPE and terminals available yet Mobile WiMAX certification process has not begun Requires operator to buy expensive licensed spectrum

Battery efficiency not known yet

Not available yet, relatively unproven in commercial deployment

Will likely follow the same path to

commoditization as Wi-Fi, including effectively free CPE in laptops by 2009

Likely to be a common public infrastructure by 2010, but not ubiquitous Bandwidth will steadily increase

Ideal for access once CPE costs approach zero Time Division, Code Division Multiple Access (TD-CDMA) and Proprietary WBA (Examples include iBURST, IP Wireless, Navini, Flarion, Soma) Typically 1-Mbps asymmetric bandwidth Scalable Excellent range (5 to 20 km)

Full mobility, including cell-to-cell handoff at vehicular speeds Battery efficient Available now, well-established and proven in commercial deployment Ideal for access

Relatively expensive base stations

Limited choice of CPE and terminals, usually from only one vendor

Window of opportunity until mobile WiMAX is ready for widespread commercial deployment in 2008

Future will depend on finalization of the IEEE 820.20 standard for mobile wireless broadband

Source: Gartner (September 2006)

Why Not Go All-Wireless Now, Both In-Building and Outdoors?

With the current hype about Wi-Fi and WiMAX, many clients planning new purpose-built offices, office moves or refurbishments have asked us whether they should avoid installing fixed wires altogether by deploying all-wireless network access.

Despite recent advances, our advice remains the same: Enterprises will need both fixed and wireless infrastructure for the foreseeable future. It is certainly true that, as work becomes more mobile, there will be more and more demand for wireless connectivity in our offices, but the fact remains that wired infrastructure will provide the best price/performance for the near future, fundamentally because wireless is a shared medium. End users who today enjoy 100-Mbps or even 1-Gbps fixed network connectivity at their desktop will be very disappointed if they become one of 10 people sharing the 54-Mbps (or even 108-Mbps) theoretical total throughput of a typical access point.

Even if 90% of enterprise applications work satisfactorily with the bandwidth delivered by

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• Media-rich interactions, such as videoconferencing or virtual collaboration. The limited latency and aggregate throughput of wireless even today means you can only get six to 10 simultaneous voice sessions into an access point. It is unlikely that a wireless access point could support more than one or two simultaneous videoconferences.

• File transfer tasks, such as backing up the 60GB disk on a desktop or laptop. Such intense traffic generated by a single user badly degrades the performance of a shared network designed to cope with shorts bursts of traffic from multiple users.

• Applications using large datasets, such as computer-aided design, geographic information systems, video editing, high-resolution digital photography and digital publishing.

Thus, most office environments will need wires and fiber as well as wireless for the foreseeable future.

RECOMMENDED READING

"Toolkit: Checklist: Choosing Wireless Broadband Technologies for the Enterprise Campus" "Cell-Fi Handsets Not Yet Ready for Mainstream Business Use"

"3G Wireless Notebooks Will Be a Futile Gold Rush"

"Distributed Antenna Systems Support Enterprise In-Building Wireless Strategy"

"When Wireless Broadband Makes Sense for Enterprise Use and the Available Technologies"

Acronym Key and Glossary Terms

3G The third-generation cellular wireless networks, which support increased voice capacity and peak data speeds up to 2 Mbps in fixed locations and up to 384 Kbps at pedestrian speeds.

CPE Consumer premises equipment — the hardware interface to the network; for wireless networks, typically a built-in wireless modem or PC Card wireless modem.

Cell-Fi A dual-mode mobile terminal that includes two radios: one for connection to cellular voice networks and one for connection to Wi-Fi networks.

WBA Wireless broadband access — a generic term for broadband access using any wireless technology.

Wi-Fi Wireless Fidelity — certification by the Wi-Fi Alliance of 802.11a, b or g standards compliance and interoperability.

WiMAX Worldwide Interoperability for Microwave Access — broadband wireless technology based on the IEEE 802.16 standards.

Wireless

Mesh A mesh topology network based on Wi-Fi standards but typically linked together by proprietary extensions today. The Wi-Fi Alliance Task Group 802.11s is developing a proposal for consideration as an IEEE standard.

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