Ahtmct-We report on the use of broadband chirp s i p nals for spread spectrum systems in indoor applications. The presented system concepts make use of chirp transmission and pulse compression. Different modulation schemes for chirp signals resulting in different system performance and complexity are compared in terms of bit error rate for the AWGN channel and for frequency selective indoor radio channels. We present simulations and measurement results from demonstrator systems which use surface acoustic waveSAW) devices for the generation and matched Altering of the chirp signals. RF and IF frequency and transmission bandwidth of the presented systems are 2.4 GHz, 348.8 MHa, and 80 MHz, respectively. Due to the processing gain of 16 dB -made possible by the use of SAW devices -and the large transmission bandwidth the system is insensitive against frequency selective fading, CW interference and noise.
Design and performance of SAW chirped delay lines on LiTa03-X1 12rotY for a wireless communication system are presented. Center frequency bandwidth and chirp rate are 350 MHz, 80 MHz, and f 2 0 MHz/s, respectively. An optimized square-root weighting was chosen to reduce the sidelobes of the compressed pulse to -42 dB compared to the correlation peak. The chirp filters have been deployed in a hardware demonstrator for a wireless indoor communication system for data rates of a few MBit/s. Limiting factors for the data rate according to simulations and measurements are mainly the intersymbol interference due to the time-overlapping of consecutive symbols and to a lower extent the multipath propagation.
A bstract-A high data-rate wideband chirp spread spectrum system for indoor communications is presented. We propose the use of chirp signals with the well known pulse compression technique to make the system extremely robust and therefore suitable for applications in industrial environment. By using rI4-DQPSK modulation of the chirp signals, overlapping &irp signals, and optimized chirp signal design we achieve data rates up to 70 Mbps. There is no need for sophis-chirp-based wideband (> 50 MHz) spread spectrum system which will be shown to be insensitive against nonidealities in the implementation (e.g. frequency offset, production tolerances, nonlinearities). As a consequence a very cheap realisation is possible. In our w ork theprocessing and generation of the needed chirp signals is done by means of surface acoustic mve (SAW) devices. They are well established in toda y's wireless communication products [4] due to their high performance and low cost.
THEORYticated digital signal processing due to the use of surface acoustic wave (SAW) filters for the generation and filtering of the chirp signals. system imperfections like production tolerances, temperature drift, nonlinearities, and others are shown to be either negligible or can be easily handeled. Simulation results reveal that the limiting faccaused by multipath propagation.The presented spread spectrum communication system is based on the well known principle of pulse compression with linear chirp signals [5]. The representation of a linear chirp waveform is giwn as (1) tor for the data rate is in tersydol interference in the time f < < $ 7 where T > a (')> fo = 2, and p are the chirp duration, the envelope,the center frequency, and the chirp rate, respectively. The chirp
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.