Pulse or digital communications – Repeaters – Testing
Patent
1997-11-26
1999-11-23
Le, Amanda T.
Pulse or digital communications
Repeaters
Testing
375347, 375349, 455137, 4552761, H04K 100
Patent
active
059913312
ABSTRACT:
A delay spread is created in a digital radio signal to reduce the coherence bandwidth and facilitate frequency hopping to reduce the effect of fading losses within an enclosed propagation environment. The delay spread is introduced into the signal in several ways. One technique disclosed employs a transmitter with two separate antennas one of which transmits the digital signal and the other of which transmits the same signal after a phase delay has been introduced into the signal. The carrier frequency of the signals is hopped between at least two frequencies and the receiver processes the resulting signals. In another embodiment, a single transmit antenna is used but the signal is received by two different antennas with the output signal from one of those antennas being phase delayed before combining it with the other prior to processing by the receiver circuitry. Phase delay is also introduced at baseband into the signals to be transmitted by rotating the I and Q components of the waveforms before modulation.
REFERENCES:
patent: 5563610 (1996-10-01), Reudink
patent: 5748669 (1998-05-01), Yada
Yoshida, S., et al., "Artificial Delay Insertion Diversity to Extend Anti-Multipath Capability of DSK in Mobile Radio," IEEE International Conference on Communications '86, No.1 (1986), 60-64.
Hook, M., et al., "Frequency Diversity Gain in Indoor GSM Systems," 1996 IEEE 46th Vehicular Technology conference, No. 1 (1996). 316-320.
Mogensen, P.E., et al., "On Antenna-and Frequency Diversity in GSM Related Systems (GSM-900, DCS-1800, and PCS1900)," 7th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications 3 (1996), 1272-1276.
International Search Report for PCT/US97/13292, dated Jun. 23, 1998.
Bottomley Gregory Edward
Chennakeshu Sandeep
Dent Paul Wilkinson
Ericsson Inc
Le Amanda T.
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