ANALYSIS OF JAMMING ON DS-UWB SYSTEM Matti Hämäläinen, Jari Iinatti Centre for Wireless Communications (CWC) University of Oulu, P.O.BOX 4500 FI-90014 University of Oulu FINLAND {matti.hamalainen, jari.iinatti}@ee.oulu.fi ABSTRACT This paper presents ultra wideband (UWB) jamming stud- ies in additive white Gaussian noise (AWGN) channel. Analytical approach for UWB system performance in the presence of partial band jamming (or interference), whose special case is tone jamming, is presented. In UWB case, most of the jamming (interference) could be seen as partial band jamming due to the extremely large inherent band- width of the desired signal. The given modifications for the existing formulas, which originally have applied for wide- band system with narrowband interference, are verified with the corresponding simulated results in UWB context. The study has focused on direct sequence (DS) based sin- gle-band UWB system that uses binary pulse amplitude modulation (BPAM) as a data modulation scheme. Jam- ming (interference) is assumed to be band limited and Gaussian distributed, and the presented analytical expres- sions allow freely spacing and arbitrary bandwidth for the interfering signal. It has been noticed that the general bit error rate (BER) formulas for wideband systems can also be applied to UWB to calculate the upper bounds for the performances using real UWB system parameters in very simply way through spectral characteristics. INTRODUCTION Due to the low transmission power and extremely wide occupied bandwidth, ultra wideband technology could provide new approach to tactical and secure communica- tions. Inherent signal structure provides low probability of interception and detection (LPI/LPD) which are essential, especially, in military applications. UWB signal’s -10 dB bandwidth could be from 500 MHz to 7.5 GHz according to the existing FCC regulations [1]. This extremely large bandwidth exposes UWB transmission to severe (un)intentional interference and jamming that will decrease the performance of the desired system. Currently, there are two competing approaches for UWB; single-band direct sequence [2] and multiband-OFDM 1 [3] based UWB techniques. The UWB standardization process 1 OFDM = orthogonal frequency division multiplexing led by the IEEE 802.15.3 [4] was unable to select one or the other proposals for a final standard. However, both technologies have their pros and cons, and have their own supporting groups. Single-band approach allows cheap implementation but is mostly limited by the maximum data rate while multiband approach that is already utilized, e.g., in wireless local area networks (WLAN) and digital video broadcasting (DVB), could offer much higher data rates but with increasing implementation complexity. Single- band approach can also be based on non-coherent detec- tion which makes the transceiver quite simple. However, non-coherent systems are more vulnerable to interference than the corresponding coherent systems. This phenome- non is further emphasized in military applications. This paper is focused on single-band UWB approach which follows more the basic idea of the impulse radio, like presented, e.g., by Scholtz and Win in [5]. Though not utilizing time-hopping mechanism, the baseband bipolar UWB pulse train obeying the polarities of the binary spreading code is used to create one data symbol. DS- UWB has been selected for the detailed study because of its better resistance against interference, see e.g. [6]. The generated pulse stream is then transmitted without fre- quency up-conversion stages thus we are dealing with the baseband communication. All the studied signals fulfill requirements given for UWB signal by the FCC [1]. Due to the extremely large occupied bandwidth, UWB re- ceiver captures lot of signal energy coming from the other radio systems than only the desired one. Radio channel generates also several multipath components that are worsening the reception. Jamming and interference de- grade the performance of the desired communication link, and its effects should be taken into account in advance as much as possible when designing a communication sys- tem. To predict the performance of UWB system, simple tools for analyzing the performance when jamming exists is therefore needed. Then, the possible need for, e.g., inter- ference suppression methods could be clarified early enough and could be taken into account in the system de- sign.