Telecommunications – Transmitter and receiver at separate stations – With control signal
Patent
1993-03-29
1995-10-10
Eisenzopf, Reinhard J.
Telecommunications
Transmitter and receiver at separate stations
With control signal
4552341, 4552401, 455127, 375345, H04B 700
Patent
active
054578132
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for automatic transmission power control in a transceiver suitable for a CDMA environment employing direct sequence diffusion.
Direct sequence spectrum diffusion technology, or DS spread spectrum technology, has to date been implemented mainly in military data communications. Information publicly available on the techniques employed in the military is scarce. The use of spectrum diffusion technology in code division multiple access (CDMA) cellular telephone systems, which are currently being designed in the U.S.A., will be one of the first commercial applications of this technology. In a CDMA network, a plurality of mobile stations (e.g. mobile phones) simultaneously share common transmitting and receiving frequencies when communicating with the base station. In DS spectrum diffusion technology, the transmitted information is modulated (multiplied) with a pseudo-random code employing a bandwidth for the code signal that is wider than the bandwidth of the information. Each mobile station has its own random or DS diffusion code, and the base station has a correlator corresponding to these. In the reception, the pseudo-random code can be demodulated with the correlator when the code used in the transmission is known.
In CDMA radio networks, a maximum number of users is achieved when the transmissions from all mobile stations are received with equal power at the fixed station. For this reason, it is necessary to monitor and control the signal powers of the mobile and fixed stations in compliance with the transmitting and receiving parameters of the equipment. The most important control systems are automatic power control (APC) of the transmitter, wherein the transmission power of a mobile station is controlled in accordance with the distance to the base station, and automatic gain control (AGC), wherein the radio receiver controls the gain in response to the signal power received.
There is hardly any data on automatic power control in a CDMA network, and the data available comprises mainly theoretical analyses on the effect of APC on the operation of the CDMA cellular network. The present invention offers practical ways of realizing both automatic gain control and automatic power control at mobile stations in a CDMA network. The method of the invention is characterized in that a setpoint signal generated for automatic gain control of the receiver is used for amplitude or power control of the radio signal sent by the transmitter.
In the prior art networks, no special attention has hitherto been paid to different modes of realizing output power control of a mobile station; in FDMA and TDMA networks including this feature, the control has been performed by commands given by the base station. In the present invention, this power control, which is indispensable in CDMA networks for the above reasons, is thus performed independently at the mobile station, without loading the radio network and without causing signalling on account thereof.
The method of the invention can be applied for instance in principle.
The automatic transmission power control concept of the invention is also suitable for use in diversity receivers.
The invention will be explained in closer detail hereinbelow with reference to the accompanying drawings in which
FIG. 1 shows block diagrams of a DS spread spectrum receiver and transmitter of a mobile station in a CDMA network,
FIG. 2 shows the sampling principle of an assembled complex baseband signal .
Hence, FIG. 1 shows a schematic block diagram of the radio components of a DS spread spectrum receiver RX and transmitter TX of a mobile station in a CDMA network. A radio signal transmitted by a base station (not drawn) is received by an antenna 1. The signal is supplied via a duplex filter 12 to an RX pre-stage 2 comprising amplifying, filtering and down-conversion functions, so that the mean frequency of the output signal of the RX pre-stage 2 is at the intermediate frequency (IF) of the apparatus. The local oscillator required by down-conversion is loca
REFERENCES:
patent: 4811421 (1989-03-01), Havel
patent: 4958359 (1990-09-01), Kato
patent: 4999583 (1991-03-01), Washburn et al.
patent: 5129098 (1992-07-01), McGirr et al.
Eisenzopf Reinhard J.
Elektrobit Oy
To Doris
LandOfFree
Method for automatic transmission power control in a transceiver does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for automatic transmission power control in a transceiver, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for automatic transmission power control in a transceiver will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2316686