Getting beyond the WiMAX hype

WiMAX (World wide Interoperability for Microwave Access) is a standardization process for the IEEE 802.16 Ethernet standards, much like Wi-Fi is the standardization process for the IEEE 802.

WiMAX (World wide Interoperability for Microwave Access) is a standardization process for the IEEE 802.16 Ethernet standards, much like Wi-Fi is the standardization process for the IEEE 802.11 standards.  WiMAX has been one of the most prolific buzz words of wireless networking for nearly two years and it is probably one of the more hyped and misunderstood technologies in recent memory.

Some of the misunderstandings of WiMAX are:

  • WiMAX is longer range than Wi-Fi
  • WiMAX is faster than Wi-Fi
  • WiMAX will compete with and replace Wi-Fi
  • WiMAX is more secure than Wi-Fi


WiMAX is longer range than Wi-Fi:
WiMAX is designed to operate in both the licensed radio band and unlicensed radio band.  When WiMAX operates in the licensed radio band, it is free to broadcast with many times more channels and power than any unlicensed radio solution so long as the broadcaster owns the license for that radio band.  This means that licensed WiMAX operation will typically be used by Wireless ISP operators.  Wi-Fi is designed to only work in the unlicensed radio frequencies in the limited 2.4 GHz and 5 GHz spectrum and is restricted by the FCC to very low broadcast power levels typically in the 1 mW to 100 mW range.  This is about one million times less power output than a typical licensed band WiMAX implementation putting out 100 kilowatts.  Is it any wonder that a WiMAX access point broadcasting at 1 million times the power levels of a Wi-Fi access point would have longer range?

While it's true that WiMAX can obviously have longer range in licensed operation, it doesn't mean that you get to put up your own kilowatt WiMAX access point willy-nilly even if you could afford the equipment.  You must own the licensed radio spectrum much like a music radio station must own their FCC license to broadcast their FM signals over the airwaves.  Put WiMAX in the unlicensed radio band like Wi-Fi and you're instantly restricted to the same power levels and scarce channels as Wi-Fi and the range advantage vanishes.  WiMAX like Wi-Fi is a wireless technology based on radio frequencies and must abide by the same physical engineering constraints.  Any technological advantage in WiMAX can easily be adopted in Wi-Fi and vice versa.  While WiMAX might for example take advantage of multi-path signals whereas original Wi-Fi implementations didn't, modern pre-N MIMO based Wi-Fi products make exquisite use of multi-path signaling.


WiMAX is faster than Wi-Fi:
WiMAX proponents often boast of its speed advantages.  While WiMAX claims to offer 70 mbps theoretical maximum bandwidth, modern Wi-Fi MIMO implementations can boast a theoretical maximum throughput of 108 mbps and sustain a real world throughput of 45 mbps.  While I can go to the local computer store and buy a production Wi-Fi MIMO access point and verify the 45 mbps sustained throughput myself, production WiMAX access points don't exist yet.  Again, the same engineering constraints and laws of physics apply and it's simply too early to talk about WiMAX throughput.

Wireless ISP implementations of WiMAX will have the same contention problems that any current wireless ISP has because the massive range of a licensed band WiMAX implementation measured in kilometers is a double-edged sword.  The fact that the coverage area is so large means that there are that many more users contending for the same spectrum and bandwidth.  Even though the wireless ISP will broadcast on multiple independent channels, there will still be many times more users on a single WiMAX channel than any Wi-Fi channel.  Every wireless ISP technology that I have ever dealt with from wireless microwave ISP access to CDPD to EDGE to Satellite all have the same over-contention and QoS (Quality of Service) issues.  Severe latency and round-trip ping times hovering erratically between 200 to 2000 milliseconds is completely unacceptable for VoIP, Video Conferencing, gaming, or any other real-time application.  While there is talk of WiMAX having QoS for VoIP, actual implementations and their effectiveness remains to be seen.  Also keep in mind that there are proven implementations of VoIP QoS for Wi-Fi in the form of Spectralink and the upcoming 802.11e wireless QoS standard.  Wireless ISP WiMAX implementations will always be slower than any unlicensed WiMAX or Wi-Fi access point because there is no way the ISP can afford to dedicate an entire channel to a few individual subscribers.

Whether or not private unlicensed WiMAX implementations will be faster than private Wi-Fi implementations will depend on specific product implementations.  While they would theoretically be the same in an apples to apples comparison with equal amounts of broadcast power and radio frequency, my money is on Wi-Fi because of the abundance and maturity of modern Wi-Fi products.  Wi-Fi has such a head start in the unlicensed market that it's difficult to imagine that WiMAX would be successful here.  This is why the vast majority of effort for WiMAX is headed for the wireless ISP market.


WiMAX will compete with and replace Wi-Fi:
The craziest of the WiMAX proponents even argue that WiMAX will entirely replace Wi-Fi and make it obsolete.  Such beliefs are over optimistic at best and irrational at worst.  WiMAX will have its place consolidating and standardizing the wireless microwave ISP market, but it will not directly compete against most Wi-Fi implementations.  WiMAX will primarily be focused on the licensed wireless ISP market while Wi-Fi will continue to dominate the private unlicensed wireless market such as the corporate or home wireless LAN.  The only place that WiMAX will overlap and compete with Wi-Fi is in the case of commercial Wi-Fi hotspots.  WiMAX clearly has the advantage of universal coverage because of its massive continuous coverage area measured in kilometers while Wi-Fi hotspots are made up of a patch work of fragmented coverage spots measured in meters.  But it is still possible that Wi-Fi hotspots will continue to thrive because of market share momentum and the fact that it can be faster with lower latency because it is short range with few subscribers to contend with.  How well WiMAX ISPs implement QoS and fight the urge to over subscribe will be the determining factor in the overtaking of Wi-Fi hotspots.  If it's anything like the over-subscribed and high-ping wireless ISP implementations of today, it will not entirely eliminate the need for Wi-Fi hotspots.


WiMAX is more secure than Wi-Fi:
One of the myths propagated about WiMAX is that it is more secure than Wi-Fi.  WiMAX will actually use a similar authentication and encryption scheme to the Wi-Fi WPA2 standard.  The minor difference is that WiMAX security will use either 3DES or AES encryption and a flavor of EAP called PKM-EAP.  Wi-Fi WPA2 on the other hand will typically use PEAP authentication along with AES encryption.  No one should make blanket statements that one is more secure than the other because good security usually depends on proper implementation of the technology if it's implemented at all.


It is important for the public to know what WiMAX is and isn't.  WiMAX and the 802.16 standards is important because it is the next logical evolutionary step for the wireless ISP industry, but it is not the be-all end-all for anything wireless.  WiMAX or any other wireless technology will always complement but never entirely replace the need for wired technology.  Wireless solutions will always be more mobile and convenient while wired solutions will always be faster and more reliable if it is possible to lay the cabling.  We need to move beyond the all the WiMAX hype and appreciate the technology for what it is.


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