WiMAX™ Implementation of MIMO

Mobile WiMAX™ is based on the IEEE 802.16e standard but is evolving in waves as it overcomes market limitations. Wave 2 products include MIMO (Multiple Input, Multiple Output) techniques. The techniques used with the smart antenna technology of MIMO makes it possible to put more data into a wireless connection and extend the range. It is expected that Mobile WiMAX with MIMO will be able to carry approximately 4x more traffic than today’s 3G networks. In this case, wireless video becomes more realistic. The unique aspect of the MIMO implementation is the use of OFDMA. In OFDMA user data bursts overlap in time. This maximizes data flow in a complex environment.

	Figure 1. OFDMA burst structure.

At any one point in time, there is data from multiple bursts available on different subchannels, as shown on the Y axis of Figure 1. These subchannels are logical arrangements of subcarriers, not physical arrangements of subcarriers. Therefore, adjacent subcarriers may actually belong to different subchannel groupings and be different modulation formats. While each data burst may only use one modulation format, adjacent subcarriers may have different modulation formats. And because each burst is unique, the pilot locations will be at many different subcarrier locations. The end result is a complexity not found in OFDM.

The complexity drives more sophisticated testing. Agilent is on the forefront of this testing. Greater insight. Greater confidence. Accelerate next-generation wireless.

^{Sources: Agilent Webinars, Wikipedia, wi-fiplanet.com}