Wireless Master

In this article, we shall talk about WiMAX. This advanced wireless system has a great advantage, which is spectral efficiency. For example, 802.16-2004 (fixed) has a spectral efficiency of 3.7 (bit/s) / Hertz, and other 3.5-4G wireless systems offer spectral efficiencies which are similar to within a few tenths of a percent. This advantage comes from combining SOFDMA with smart antenna technologies, and thus multiplies the effective spectral efficiency through multiple reuse and smart network deployment topologies. The direct use of frequency domain organization simplifies designs using MIMO-AAS compared to CDMA / WCDMA methods, and this means a more effective system.

Of course, WiMAX is not without its share of limitations. One major misconception about WiMAX is that it can deliver 70 Mbit/s over 50 kilometers. However, this is not true. WiMAX can actually operate either at higher bitrates or over longer distances, but certainly not both. Operating at the maximum range of 50 kilometers increases the bit error rate, and this would result in a lower bitrate. On the other hand, reducing the range to less than 1 kilometer would allow a device to operate at higher bitrates. Today, no one knows of any examples of WiMAX services being delivered at bitrates of higher than 40 Mbit/s.

Usually, the fixed WiMAX networks have a higher-gain directional antenna installed near the client or customers, and this results in a greater increased range and throughput. Mobile WiMAX networks are most usually made of indoor customer-premises equipment (CPE), like laptops with integrated mobile WiMAX, desktop modems, etc. The mobile WiMAX devices usually have omnidirectional antennae, which are of lower-gain, as compared to the directional antennas, but these are more portable. In the current deployments, the throughput may reach 2 Mbit/s symmetric at 10 km with fixed WiMAX, and a high gain antenna. One should also consider that a throughput of 2 Mbit/s can mean 2 Mbit/s symmetric simultaneously, 2 Mbit/s symmetric or some asymmetric mix (for example, 0.5 Mbit/s downlink and 1.5 Mbit/s uplink or 1.5 Mbit/s downlink and 0.5 Mbit/s uplink). These all require slightly different network equipment and configurations. But of course higher-gain directional antennas can be used with a WiMAX network with range and throughput benefits, but there would be an obvious loss of practical mobility.

Now let’s talk about the WiMAX Forum. This is basically a non-profit organization which was formed to promote the adoption of products and services which are compatible with WiMAX. The organization focuses on certifying the interoperability of WiMAX products. The products and services that pass the conformance and interoperability tests get the “WiMAX Forum Certified” designation, and then this mark can be displayed on their products and marketing materials. Those products and services that have not got an official certification from the WiMAX Forum usually claim that their equipment is “WiMAX-compliant” or “WiMAX-ready”.

Finally, WiMAX Forum also promotes widespread knowledge about WiMAX. Their certified training program is offered in French and English, and the Forum also holds regular member events, and even endorses some industry events.