By Lisa Johnston
New products on display at the American International Toy Fair, held in N
Future Bluetooth and HomeRF networks could be designed to completely eliminate interference with IEEE 802.11b (WiFi) wireless networks under FCC rules changes, the HomeRF working group said.
The changes to the FCC's Part 15 rules apply to wireless products that operate in the unlicensed 900MHz, 2.4GHz, and 5.7GHz bands.
The changes, said commissioner Kevin Martin, will "encourage even greater [spectrum] sharing and result in a more diverse set of products to operate in the unlicensed bands." They would also enable cordless-phone manufacturers to use new modulation technologies to prevent interference with other devices in the bands.
Under the FCC's new rules, suppliers could use new digital modulation techniques in the bands to supplement the currently allowed direct sequence spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS).
Specifically, future 2.4GHz devices — including cordless phones, Blueooth devices, and HomeRF devices — would be allowed to use adaptive FHSS to eliminate interference with other 2.4GHz devices, including 802.11b (WiFi) wireless-network devices and future 2.4GHz 802.11g network devices. The current Bluetooth and HomeRF specs use nonadaptive FHSS technology.
Adaptive FHSS lets devices hop around the three static channels that a WiFi device or other product might already be using. Nonadaptive FHSS devices, on the other hand, occasionally hop into the same part of the band as a WiFi stream because the devices hop in sequence through dozens of channels spread out across an entire band.
All three unlicensed bands — 900MHz, 2.4GHz, and 5.7GHz bands — would also be allowed to use such new modulation techniques as Orthogonal Frequency Division Multiplexing (OFDM). That change would let suppliers begin marketing wireless-network devices using the IEEE's 2.4GHz 54Mbps 802.11g spec, which is OFDM-based.
IEEE's 802.11a (WiFi5) standard already uses OFDM but operates in the unlicensed 5.15-5.35GHz band, where OFDM is already allowed.
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