Steven J. Crowley, P.E.
The FCC recently issued an order denying reconsideration petitions in its ultra-wideband (UWB) proceeding. That effectively ends the 12-year UWB rulemaking process. Mitchell Lazarus recounts how UWB became bogged down at the FCC and in a failed standardization attempt in IEEE 802.
UWB, as authorized by the FCC, operates across 3.1 to 10.6 GHz, with very low power at any one frequency; its tendency to cause or receive interference is very low.
IEEE 802 attempted to create a UWB standard in IEEE 802.15.3a but did not, as neither of two competing proposals reached the necessary voting threshold for approval. One of the competing proposals, Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM), has since seen some consumer success in Wireless USB, which is based on a platform maintained by the WiMedia Alliance; data rates are up to 480 Mbps at a range of about 10 feet.
UWB was eventually standardized in IEEE 802.15.4a, where it exists as an alternative physical-layer to standard IEEE 802.15.4-2006, a standard for very low power, low data rate devices. (The IEEE 802.15.3 family is for higher data rates with higher power consumption.) It uses what was the other competing proposal in 802.15.3a, Direct Sequence UWB (DS-UWB). This standardized form of UWB has been commercialized for asset tracking and other location services, but not yet for consumer applications.
As Lazarus says, though UWB is successful in several applications outside the home, it has not made as much progress in the consumer market. A big reason for this is that UWB’s competitors were not so encumbered with regulatory and standardization delays.
- Standard IEEE 802.11n-2009 (high-throughput Wi-Fi) was approved a year ago with uncoded bit rates up to 600 Mbps in a 40 MHz bandwidth at 2.4 or 5 GHz.
- The Wireless Home Digital Interface (WHDI), which operates in 40 MHz of bandwidth in the 5 GHz unlicensed band, was standardized late last year by the WHDI Consortium. The targeted market is transmission of uncompressed (better-quality) HD video, with data rates up to 3 Gbps. IEEE 802 was not involved, though the technology is similar to 802.11n.
- There are two new millimeter-wave technologies that offer multi-gigabit data rates. These 60-GHz technologies are not direct competitors with UWB, but some overlap in applications could emerge. The data rates are much higher, but 60 GHz is blocked by most any obstruction, and power consumption is high making it unsuitable for mobile devices at this time. As with WHDI, the main market is the transmission of uncompressed HD video.
WirelessHD operates in the 57-64 GHz unlicensed band and is based on the IEEE 802.15.3c-2009 standard that was published about a year ago. The Wireless Gigabit Alliance is another 60 GHz proponent; its specification is to be based on the IEEE 802.11ad standard, which is under development and should be completed around the end of 2012.
If someone tried to standardize UWB in IEEE 802.15.3 today, they would have a better chance of success due to meeting process improvements. In making decisions in IEEE 802, it has traditionally been one-person, one-vote. That has sometimes motivated companies to send as many as possible to the standards meetings so they can earn voting rights and vote as a block, a practice frowned on by ANSI, IEEE 802’s accrediting body. Since the failure of the UWB standardization in 802.15.3, and because of evidence of block voting in other groups, IEEE 802 has modified its voting procedures to make block-voting harder. Everyone participating in the meetings now has to declare an “affiliation,” the definition of which is carefully worded to lead to the primary entity paying the participant. Consultants, for example, have to declare affiliation with their client, not their consulting firm; they often didn’t do this before. If roll-call votes show evidence of block voting, the group may be switched to entity voting (e.g., one company, one vote). That helps. IEEE 802.20 got bogged down, switched to entity voting, instantly made progress and completed its standard.
With these and further process improvements, IEEE 802 is a good home for these unlicensed standards. One advantage is that all IEEE 802 wireless projects are required to address coexistence with other IEEE 802 wireless standards. That’s hard, as many are using the same spectrum, but the affected groups sometimes can make accommodations with each other to reduce mutual interference. Also, many companies prefer the more-open process of an accredited standards development organization. The decision to go it alone or with a proprietary specification, however, is ultimately a business decision.
UWB remains unique in terms of its interference-resistant characteristics. As more RF devices enter the home, as they will with increased machine-to-machine communications, UWB could help as the more-popular relatively-narrowband devices increasingly interfere with each other. UWB may then become successful in the home out of necessity, if not as an option.