Improved Wireless Reliability Using Fast-Hopping HybridSpread Spectrum

摘要

Existing wireless technology used in industrial applications hinges on either direct-sequence spreadspectrum (DSSS) or frequency-hopping spread spectrum (FHSS). While FHSS has been commonwithin the military because it is easier to deploy in a dynamic network, DSSS has been morecommonly used for infrastructured systems such as code division multiple access (CDMA) cell phonesbecause it provides higher spectral efficiency and is much less likely to upset sensitive electronicequipment in plants. By combining the spectral diversity of FHSS, the multipath resistance of DSSS,and other modulation techniques in a hybrid system that “hops” the carrier on the order of the bit rate,wireless communication links can be made much more reliable. Three key benefits will be addressed inthis paper: (1) reduction of the effects of short-length multipath, which is often encountered inindustrial settings; (2) improvement in the ability to combat the “near-far” problem; and (3) the abilityto adapt to a variety of channel problems. These problems include zones that include a complexcombination of reflective metal surfaces, potential interference signals, and extremely complicatedelectro-magnetic environments. Improvements in these effects can allow designers to reducetransmitted power, thereby improving battery life and/or increasing range. As the industrial wirelessmarketplace matures, technologies that can address industrial needs are needed to reach the marketpenetration expected and yield the gains in productivity and efficiencies anticipated. This technologycan potentially address many of the industrial issues impeding adoption in the current applications.