Interference from coexisting narrowband services is a critical factor affecting performance of ultra-wideband (UWB) radio communications. There is clearly a need to quantify interference and compare UWB systems on that basis. In this paper, we develop a general Rake reception model along with a unifying transmission framework for low duty-cycle UWB multiple access encompassing existing and novel spreading codes, including direct sequence, digital single- and multi-carrier, time-hopping, and combinations of them. Our unifying framework relies on a digital model, which leads to closed-form performance analysis expressions. Different from existing alternatives that require oversampling, our general model is developed directly from the samples of the Rake receiver output and allows for various Rake finger delay selections. Signal-to-interference-plus-noise ratio analysis and simulations are carried out to assess the relative merits of several UWB systems in the presence of narrowband interference, multipath and additive white Gaussian noise, for both matchedfilter and minimum mean square error Rake receivers.
Bibliographical noteFunding Information:
Manuscript received August 2, 2003; revised February 11, 2004; accepted April 24, 2004. The editor coordinating the review of this paper and approving it for publication is Z. Tian. Prepared through collaborative participation in the Communications and Networks Consortium sponsored by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Co-operative Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. This work is also supported by the National Science Foundation under Grant EIA-0324864.
- Direct sequence (DS)
- Multi-carrier (MC)
- Narrowband interference (NBI)
- Single-carrier (SC)
- Time-hopping (TH)
- Ultra-wideband (UWB)