Differential, transmitted reference (TR) and energy detection (ED) based ultra-wideband impulse radios (UWBIR) can collect the rich multipath energy offered by UWB channels with a low-complexity receiver. However, they perform satisfactorily only when the channel induced inter-pulse interference (IPI) is negligible. This can be achieved by appending a guard interval with duration greater than or equal to the channel's delay spread to each frame - an operation limiting the maximum achievable data rate. As a remedy, this Letter advocates block transmissions in conjunction with orthogonal spreading sequences to remove the introduced IPI. The resultant scheme requires no channel knowledge besides timing offset and incurs slightly more complexity than non-block alternatives, while it increases the data rate at no cost in error performance. Given a fixed data rate of 25Mbps, the novel block scheme exhibits about 1.8 dB gain relative to its non-block counterpart in single-user simulated tests.
Bibliographical noteFunding Information:
Manuscript received July 19, 2006; revised January 17, 2007 and November 18, 2007; accepted November 24, 2007. The associate editor coordinating the review of this paper and approving it for publication was Y. Ma. This work was supported by the NSF-ITR Grant No. EIA-0324864, NSF-MRI Grant No. CNS-0420836, and through collaborative participation in the Communications and Networks Consortium sponsored by the U. S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. Part of the results in this paper has appeared in the Proc. of GLOBECOM Conf., San Francisco, CA, Nov. 27-Dec. 1, 2006.
- Differential modulation
- Impulse radio
- Orthogonal code
- Transmitted reference