In August, the Federal Communications Commission (FCC) amended Part 15 of the Commission’s rules governing the operation of frequency hopping spread spectrum (FHSS) devices in the unlicensed 2.4 GHz frequency band. This change came after a year of concerted opposition from those companies that backed other wireless technologies (i.e., IEEE 802.11b and Bluetooth), which operated in the same frequency band. The upshot of this regulatory decision is that it would allow for wideband frequency hopping (WBFH), thus permitting the Home Radio Frequency Working Group (HomeRF) to revise its Shared Wireless Access Protocol (SWAP) specification to scale to data rates of 10 Mbps.
The HomeRF petitioned the FCC for a rule change in November 1998, asking for the ability to hop at wider channel widths of 3 MHz and 5 MHz. This would respectively allow for 6 Mbps and 10 Mbps raw data rates. SWAP 1.3 currently employs a channel width of 1 MHz that results in a 1.6 Mbps data rate.
In June 1999 the FCC issued a Notice of Proposed Rule Making (NPRM), which was a step toward the official amendment. Since then, the FCC has been deluged by arguments and evidence from both supporters and opponents to the proposed amendment. The chief opponents included the Wireless Ethernet Compatibility Alliance (WECA), individual IEEE 802.11b vendors and Bluetooth Special Interest Group (SIG) backers.
The main argument put forward by these opponents was that a rule change would create additional interference with other spread spectrum devices operating in the unlicensed band, notably those that were IEEE 802.11b and Bluetooth compliant.
From a strategic perspective it was also clear that IEEE 802.11b vendors were keen to avoid competition from another high-speed wireless local area network (WLAN) technology. The issue of direct sequencing spread spectrum (DSSS) vs. FHSS appeared to be a replay of the fragmentation that had plagued the original IEEE 802.11 standard. The key difference now is that FHSS devices are primarily being targeted at the residential market, not the larger and more mature enterprise market.
The FCC eventually agreed with most of HomeRF’s arguments and issued its decision with modifications to the NPRM. The FCC clearly saw that competition from WBFH devices to DSSS systems was healthy for the market. It also appreciated the objectives of the HomeRF, notably affordable wireless home networking and the ability to support multiple high-quality voice channels.
The evidence presented against the NPRM, that interference would be a serious obstacle to further product development and market growth, failed to convince the FCC. The FCC noted that consumers should be cognizant that a degree of interference is to be expected with the operation of devices in, what is ultimately, an unlicensed frequency band.
However, the FCC did modify the NPRM in two ways to reduce the level of possible mutual interference. WBFH devices would not be allowed to use overlapping channels, and the output power would be reduced to 125 MW (vs. 200 MW requested initially by HomeRF).
For HomeRF, the FCC decision, while a long time coming, is a major victory. Without a positive decision there was a real possibility that HomeRF would have been fatally caught in a pincer movement between IEEE 802.11b’s higher bandwidth and Bluetooth’s lower cost.
The ability to scale to higher data rates is important to HomeRF for a couple of reasons. First, it will allow HomeRF to address distribution of multimedia content within the home. An MPEG-2 video stream is typically between 3 Mbps and 8 Mbps. Residential gateway vendors are looking to add wireless access point functionality to their platforms, and hope to support such multimedia streams. Thus, HomeRF needed the additional bandwidth to support more than just basic data streams, and to be a viable option for residential gateway vendors. Second, the uncertainty over the NPRM had slowed the momentum of HomeRF as interested product developers failed to follow through on their initial product plans. The capability to use WBFH will increase the likelihood of additional vendors developing SWAP-compliant products.
For backers of IEEE 802.11b, the FCC decision is a blow, but not a severe one. The downsides of the decision are that it adds to the specter of WLAN fragmentation, specifically in the residential market, and that it will lead to a greater possibility of interference in the 2.4 GHz band.
Currently, DSSS-based IEEE 802.11b products are more expensive than FHSS devices, and so in the residential market SWAP-compliant products possess a cost advantage. Nevertheless, IEEE 802.11b products are becoming cheaper with a ramp-up in silicon volume and better chip integration. In due time, IEEE 802.11b-compliant products will be even more aggressively targeted at the price-sensitive home market.
An ace up the sleeve of IEEE 802.11b backers is that the IEEE is currently looking to revise the IEEE 802.11b specification for data rates of up to 22 Mbps. When, and if, these 22 Mbps products become available, they should reestablish the performance delta with SWAP-compliant products.
The success of HomeRF will depend on the ability to execute perfectly on its strategy in the next 12 months. This will mean that HomeRF backers need to use the superior cost profile of FHSS devices to drive significant market penetration, before the volume ramp-up in IEEE 802.11b products nullify this advantage. In order to achieve this, it is critical that HomeRF attract additional vendors to actively develop SWAP-compliant products. The core group of HomeRF supporters – Proxim, Intel, Motorola, IBM, Compaq and Siemens – by themselves cannot survive the onslaught of IEEE 802.11b products that will surely be unleashed by WECA members.
Allied Business Intelligence Inc is an Oyster Bay, NY-based technology research think tank specializing in communications and emerging technology markets. ABI publishes strategic research on the broadband, wireless, electronics, networking and energy industries. Details of these studies can be found at www.alliedworld.com , or call 516-624-3113 for more info.