Differences between version 4 and predecessor to the previous major change of FHSS.
Other diffs: Previous Revision, Previous Author, or view the Annotated Edit History
| Newer page: | version 4 | Last edited on Wednesday, October 22, 2003 10:10:49 am | by StuartYeates | Revert |
| Older page: | version 1 | Last edited on Thursday, September 4, 2003 11:12:48 pm | by AndersGreen | Revert |
@@ -1,3 +1,5 @@
-[
FHSS] is
an [Acronym
] for ''Frequency Hopping Spread Spectrum''
and was used in the original [802
.11] standard
but was replaced
with [
DSSS]
+Frequency-hopping spread spectrum (
FHSS) or direct-sequence spread spectrum (DSSS) technology. FHSS systems are targeted at low-cost low-power low-range low-data-rate applications, and include Bluetooth, HomeRF (SWAP), 2.4GHz DECT (digital European cordless telephone), and FHSS IEEE802.11. The DSSS IEEE802.11b systems are intended for higher-data-rate and higher-range applications, and typically cost more and consume more power. BlueTooth systems are directed at data transfer, such as transferring
an e-mail message from a cell phone to a
[PDA
],
and support data rates up to 721kbps. HomeRF supports both data and voice transmission, and allows data rates up to 1.6Mbps. Carrying over from its past incarnation at 1.9GHz, 2.4GHz DECT is intended for 2.4GHz cordless phones with a data rate of 552kbps. IEEE802
.11 FHSS systems currently support data rates up to 1.6Mbps,
but a new 5-MHz channel BandWidth allocation, wideband FH, will allow symbol rates up to 10Mbps. This will let FHSS compete
with the current 11Mbps symbol rates supported by
DSSS systems.
-Read more at [ webopedia
.com | http://www
.webopedia
.com/TERM/F/
FHSS.html ]
and [ wireless
-nets.org |http://www
.wireless
-nets
.com/articles/whitepaper_spread.htm ]
+For FHSS, the 2
.40GHz to 2
.835GHz ISM band is broken into 75 1MHz channels, with a 2MHz lower guard band and a 3
.5MHz upper guard band. All
FHSS systems are based on TDMA, with the number of frequency hops per second varying from one standard to another
. Bluetooth
and DECT utilize Gaussian frequency
-shift keying (GFSK) modulation, whereas HomeRF and [FHSS] 802
.11 use 2
-level and 4-level frequency-shift keying (FSK)
.
+
+AddToMe
