Modulating Signal

0273-EX-ST-2003 Text Documents

Georgia Institute of Technology

2003-07-25ELS_62194

DSRC Exhibit A Channel Sounding in the 2.4 GHz Band Three are the most common sounding techniques for wideband mobile radio channels1: direct pulse, swept frequency measurement, and spread sliding correlator measurements. Out of the three, the most universal but sophisticated form of multipath analysis is the sliding correlator spread spectrum channel sounder. For spread spectrum wireless engineers, this approach has been an additional benefit because it mimics the type of transmission and reception hardware that is used in code division multiple access (CDMA) telephone systems. There are some commercial sounders where the RF transmitted stimulus signal and the analysis receiver are tuned to within the band to be measured and the results are calculated and displayed in real-time. Our approach utilizes an off-line system where we record the data in real time for further processing. We will use two vehicles for our mobile-to-mobile channel characterization. In one vehicle, we will have the signal generation or transmission as show in Fig. 1. 8 dBi omnidirectional Spread Spectrum Agilent ESG4438C signal Microwave Signal design using generator with amplifier for 30.8 Matlab arbitrary waveform option dBm output Figure 1. Channel Sounder Transmitter. 1 Parsons, J. D.; Demery, D. A.; Turkmani, A. M. D., “Sounding techniques for wideband mobile radio channel: a review,” IEE Proceedings, vol.138, No. 5, pp. 437-46, October 1991.

We will have the receiver in another vehicle. We show the receiver in Fig. 2. 8 dBi omnidirectional Digital Radio IF FPDP to PCIx Receiver FPDP LNA Down-conversion Matlab Pentek 6216 I&Q Apcom 1610 Processing Pentek 4291 VME Bus Figure 2. Channel Sounder Receiver. • Transmission signal We plan to use a spread spectrum signal with the characteristics shown in Table 1. Table 1. Channel Sounding Signal Specifications Parameter Value or Description Tc = chip period 25 nanoseconds Spreading signal Maximum length sequence (MLS) of order nine and length 29 − 1 = 511 Primitive polynomial 1 + x4 + x9 Symbol modulation bpsk Tb = symbol period 12.775 µs Speed of keying 78277 bps Code gain 54.16 dB Bandwidth 40 MHz Output Filter Raised Cosine with rolloff factor β = 0.5 • Output Filter Mask

Spread Signal Spectral Mask 10 0 10 Magnitude, dB 20 30 40 50 60 80 60 40 20 0 20 40 60 80 Frequency, MHz


Document Created: 2003-07-25 16:10:56
Document Modified: 2003-07-25 16:10:56
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