WiMAX Edges Into the Mainstream

Sprint Nextel made the headlines in August with the announcement that it is to splash out $4.5 billion on a nationwide wireless WiMAX network to be built over the next couple of years. If all goes according to plan it will be used as a high bandwidth mobile network which will leapfrog 3G in terms of its video conferencing and fast data transfer capabilities.

But what about fixed WiMAX? Worldwide Interoperability for Microwave Access (WiMAX) (define) was originally introduced in October 2001 as the IEEE 802.16 standard, defining the air interface or PHY layer, as well as the MAC (Media Access Control) (define) layer. The fixed WiMAX standard, 802.16d-2004, was released three years later, allowing non line of sight connections and setting OFDM as the transmission protocol.

There’s been much talk that fixed WiMAX has a range of seventy or eighty miles, offering speeds of 48Mbps or more, but in reality bandwidth drops rapidly with range. So where fixed WiMAX has been or is planned to be deployed, it’s generally over a range of up to about ten miles, offering connections similar to DSL, T1 leased lines or even T3s. Its uses have been mainly as an alternative “last mile” broadband connection to homes or offices, and as a backhaul connection for Wi-Fi hotspots and even 3G base stations.

Whatever the applications, sales of WiMAX equipment are growing strongly, albeit from a low base. WiMAX equipment sales hit $142.3 million last year, according to CA-based research house Infonetics, with a five year unit combined annual growth rate forecast at 139% between 2005 and 2009.

As a “last mile” connection to the Internet, fixed WiMAX can offers a number of advantages over a leased line or DSL alternatives. In some buildings in large cities there is no copper available to provide DSL, and a T1 line can take too long to get up and running. A WiMAX connection can in theory be installed by mounting a dish in a matter of hours.

WiMAX has the obvious drawback that it is not available everywhere, but in some parts of selected cities such as New York, Chicago, Boston, Los Angeles and San Francisco it is available. The evidence from users here is that where it is available it works well and is cheaper than more conventional connection methods. “We have a T1 capacity WiMAX connection and we pay about one half of what we used to pay for a conventional T1 connection from our telco, and it’s much more reliable,” says Jim Sulley, principal at New York based media library Newscast. The company gets its WiMAX connection from a base station on the Empire State Building operated by MA-based TowerStream. One of the advantages of WiMAX is that service providers like TowerStream can deliver it at arbitrary bandwidths, instead of discrete capacities such as T1 or T3. This means that if a customer like Newscast has a need for more bandwidth for a short period of time – for example a once weekly overnight offsite backup – the service can be “turned up” to 5Mbps. “So essentially, we get 3 T1s when we need it for less than half the price of a T1,” says Sulley.

WiMAX is an interesting “last mile” solution, but it also looks extremely attractive as a WAN technology to link buildings on a campus, or offices on different sides of a city. Of course if two offices have WiMAX links to the Internet it’s possible to set up a VPN between the two, but some WiMAX service providers like Canada-based Redline Communications sell equipment that enables high speed point to point connections over distances of several miles, and a theoretical range of up to about 50 miles.

This differs from services offered by companies like TowerStream in that a WiMAX-based WAN can be set up anywhere. There are practical considerations of course: WiMAX requires line of site or near line of sight, so a mountain range between two sites will certainly stymie it.

But essentially it is possible to connect two sites up to 10 miles apart with a fast link, according to Redline, however remote they are from traditional high bandwidth infrastructure, if there aren’t any buildings or trees in the way. If there are, it is often possible to overcome this by mounting equipment on a relatively modest mast.

The cost of a WiMAX link is surprisingly low. Redline’ AN80 Ethernet bridge devices, for example, cost $4,000 per pair, providing a 10Mbps data link. If you factor in the cost of running a cable from the roof of the office to the data center, and a support contract of about $600 per year, its pretty clear that a WiMAX set up replacing a single T1 leased line could pay for itself in about a year.

Redline’s devices – and probably most others as well – provide basic DES encryption, which makes the WiMAX connection at least as secure as an unencrypted leased line. With additional hardware this can be enhanced to government grade crypto. Any other appliances, such as caches, compressors or wide area file system (WAFS) devices, which can be used on conventional WAN links can also be connected to the WiMAX devices.

A drawback to a WiMAX based WAN – aside from the fact that it may not be possible to build one at all if the line of site is not clear enough – is that the latency of the connection is likely to be about 1ms, twice as much as a typical T1 line, although in practice this is unlikely to be noticeable in most circumstances. There’s also the worry that the technology is relatively new, and that, as in any new industry, the vendors who are the pioneers may not be the ones that stay the course.

But it’s hard not to conclude that the economics of WiMAX look tempting. A 10Mbps WAN for $600 a year with an initial investment of $4,000 plus installation, or T1 Internet connectivity for half the price of a leased line – with the option of turning it up to 5mbps when necessary? It sounds good. There’s no reason to expect a WiMAX connection to be less reliable than a T1 from your telco, and the weather really won’t make any appreciable difference to your connection. If your connectivity bills are getting to high or you want more flexibility in the bandwidth available to you, WiMAX is certainly worth looking into.

Paul Rubens
Paul Rubens
Paul Rubens is a technology journalist specializing in enterprise networking, security, storage, and virtualization. He has worked for international publications including The Financial Times, BBC, and The Economist, and is now based near Oxford, U.K. When not writing about technology Paul can usually be found playing or restoring pinball machines.

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