WiMAX Forum denies FDD profile is imminent
The WiMAX Forum was swift to debunk the notion that it is set to reveal an FDD profile for mobile WiMAX within six months. We reported on a recent article in telecoms.com, in which Paul Senior, chief technology officer of WiMAX vendor Airspan, said the WiMAX Forum was set to introduce an FDD profile and has been hush-hush about the move because it wanted to get IMT-2000 approval first and avoid the firestorm that an FDD profile would have created.
The WiMAX Forum is adamant no decisions have been made on an FDD profile, and therefore it has no official timeline pertaining to releasing one.
"There is discussion but it hasn't gotten to the point where we would be able to create a timeline," Tim Hewitt, regulatory working group chair with the WiMAX Forum, told FierceBroadbandWireless. "It all comes down to what our members want to do."
Why is this discussion significant? FDD mode, or frequency division duplex, sends and receives information using separate channels for the uplink and downlink. Today, mobile WiMAX uses TDD, or time division duplex, signaling, which assigns time slots for both the uplink and downlink signals. The IMT-2000 Extension Band is harmonizing 2 x 70 MHz for FDD spectrum internationally, leaving 50 MHz for TDD technologies like WiMAX. Moreover, much of the 700 MHz band's spectrum, including the coveted C-block, is configured for FDD signaling.
In light of this, I'd argue that the WiMAX community needs a solid story when it comes FDD, especially since the technology's backers have high hopes for mobile WiMAX in the 700 MHz band.
The WiMAX world was smart to focus on TDD for mobility to make use of that under-utilized spectrum around the world. As Hewitt says, TDD spectrum is easier to find than FDD spectrum, which requires paired spectrum. Now, with the blessing of the International Telecommunication Union, the WiMAX community is creating an ecosystem in the TDD band that will enable it to more effectively compete with technologies such as HSDPA and LTE in FDD bands.
Of course, there are some political issues I can dream up as to why the WiMAX Forum needs to be careful about pitting itself aggressively against HSDPA, EV-DO and LTE in the paired bands. One is that the forum's major members are vendors and operators that also have established revenue-generating businesses in these paired-band technologies. Moreover, continuing to emphasize the TDD band creates an opportunity for WiMAX to be the most viable option for unpaired spectrum with little competition.
Read more about the WiMAX Forum's views on this issue here.--Lynnette
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Posted by Jim A | January 24, 2008 - 11:34am
Good piece Lynnette.
Of course the WiMAX forum will try and downplay this. They are trying to make sure they get the existing WiMAX systems released in the market and they do not need any distractions. This is especially an irratant to those vendors who have spent all their resources developing existing 2.5Ghz (in the US) based products and now find a major radio vendors introducing a new and improved product concept based on the new 700Mhz and future White Space (400Mhz) spectrum, which is far superior to the marginal 2.5Ghz systems (major Foliage issue in Rural markets) which are mainly targetted at Urban markets.
When we combine WiMAX features with FDD and 400-700Mhz spectrum you have a winner that is a major distraction to the ongoing efforts in deploying existing systems.
This is also a serious issue with the CellCo's, some of which are also members of the Forum (for this very reason). They see these new WiMAX radios as a major threat to their existing 3G and even 4G networks.
Jim
