Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-04-25
2002-09-10
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S426100, C455S552100, C455S063300, C455S561000, C455S423000, C455S446000
Reexamination Certificate
active
06449477
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to reception of electromagnetic signals, and specifically to reception of electromagnetic signals in enclosed regions.
BACKGROUND OF THE INVENTION
In cellular communications systems there are typically regions where the coverage is difficult or incomplete, for example, within metal-framed structures, and underground. Methods for improving the coverage in regions such as these are known in the art.
U.S. Pat. No. 5,404,570, to Charas et al, whose disclosure is incorporated herein by reference, describes a repeater system used between a base transceiver station (BTS), which is able to receive signals, and a closed environment such as a tunnel, which is closed off to transmissions from the BTS. The system down-converts a high radio-frequency (RF) signal from the BTS to an intermediate frequency (IF) signal, which is then radiated by a cable and an antenna in the closed environment to a receiver therein. The receiver up-converts the IF signal to the original RF signal. Systems described in the disclosure include a vehicle moving in a tunnel, so that passengers in the vehicle who would otherwise be cut off from the BTS are able to receive signals.
U.S. Pat. No. 5,603,080 to Kallandar et al., whose disclosure is incorporated herein by reference, describes a plurality of repeater systems used between a plurality of BTSs and a closed environment, which is closed off to transmissions from the BTSs. Each system down-converts an RF signal from its respective BTS to an IF signal, which is then transferred by a cable in the closed environment to one or more respective receivers therein. Each receiver up-converts the IF signal to the original RF signal. Systems described in the disclosure include a vehicle moving between overlapping regions in a tunnel, each region covered by one of the BTSs via its repeater system. Thus, passengers in the vehicle who would otherwise be cut off from one or more of the BTSs are able to receive signals from at least one of the BTSs throughout the tunnel.
U.S. Pat. No. 5,765,099, to Georges et al., whose disclosure is incorporated herein by reference, describes a system and method for transferring an RF signal between two or more regions using a low bandwidth medium such as twisted pair cabling. In a first region the RF signal is mixed with a first local oscillator to produce a down-converted IF signal. The IF signal is transferred to a second region via the low bandwidth medium, wherein the signal is up-converted to the original RF signal using a second local oscillator. The local oscillators are each locked by a phase locked loop (PLL) in each region to generate the same frequency, the locking being performed in each loop by comparing the local oscillator frequency with a single low frequency stable reference signal generated in one region. The reference signal is transferred between the regions via the low bandwidth medium.
U.S. Pat. No. 5,513,176, to Dean et al., whose disclosure is incorporated herein by reference, describes a distributed antenna array within a region where reception is difficult. The performance of the antenna array is enhanced by generating signal diversity within the array. Each antenna in the array has a differential time delay applied to signals that it receives, thus generating received signal diversity. The differentially-delayed signals are preferably down-converted to an intermediate frequency and are then transferred out of the region via a cable.
U.S. Pat. No. 5,930,293, to Light, et al., whose disclosure is incorporated herein by reference, describes a wireless repeater comprising first and second spatially-separated antennas. Both antennas receive a signal from a transmitter, and the signal received by the second antenna has a time delay added to the original signal. The two signals are summed to form one aggregate signal, which is transmitted from a third antenna. A receiver of the aggregate signal is able to reconstruct the signals received by the first and second antennas.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide an arrangement of transceivers of electromagnetic wireless signals that improves the reception of the signals within an enclosed region.
In preferred embodiments of the present invention, a plurality of wireless slave transceivers are positioned within a multistory building, in locations that are generally cut off from external electromagnetic radiation. The plurality of slave transceivers are divided into two sub-groups of slave transceivers, typically a main group and a diversity group, as is known in the art. Both sub-groups of slave transceivers transfer signals to and from a master transceiver via cables. The master transceiver communicates with one or more base transceiver stations (BTSs), typically associated with a cellular communications network. Preferably, at least one of the BTSs is outside the building. Optionally, at least one of the BTSs is inside the building, in which case these BTSs preferably communicate with a base station controller. Alternatively, the at least one BTS within the building, the master transceiver, and the plurality of slave transceivers, form a generally closed communications network. The slave transceivers are positioned within the building so that a mobile transceiver, for example a cellular telephone, within the building is generally able to transfer signals to and from at least one of the plurality of slave transceivers in each of the sub-groups. Thus, the mobile transceiver communicates with the one or more BTSs via the slave transceivers and the master transceiver.
For the purposes of preferred embodiments of the present invention, a near side and a far side of the building are selected for the purpose of positioning the slave transceivers. The choice of “near” and “far” is arbitrary, wherein the object of the choice is that the near and far sides be as distant from one another as is practical, given any other constraints that may be imposed on the locations of the transceivers. On each even floor a slave transceiver from the first sub-group is positioned at the near side of the building, and a slave transceiver from the second sub-group is positioned at the far side of the building. On each odd floor, a slave transceiver from the first sub-group is positioned at the far side of the floor, and a slave transceiver from the second sub-group is positioned at the near side.
The transceivers are thus positioned throughout the multistory building in an alternating pattern. On any specific floor the transceivers of the first and second sub-groups are separated because the respective transceivers are at opposite ends of the building. Thus the transceivers of each sub-group can operate as main and diversity transceivers respectively. Between different floors of the building, the transceivers within each sub-group are separated by two floors because of the alternating pattern described above, so that the smallest vertical separation of transceivers within the sub-group is two stories. This is approximately double the separation afforded by in-building coverage systems known in the art, in which the transceivers are not in an alternating pattern. By increasing the separation of slave transceivers within each sub-group, interference effects caused by slave transceivers within the sub-group transferring the same transmission to or from the mobile transceiver are significantly reduced.
There is therefore provided, in accordance with a preferred embodiment of the present invention, a method for communicating between a mobile transceiver in a multistory building and a wireless communication network, the building including alternating even and odd floors and having a near side and a far side, the method including:
dividing a plurality of slave transceivers into a main sub-group of slave transceivers and a diversity sub-group of slave transceivers, the transceivers being operative to transmit signals of a type which are conveyed over the wireless communication network;
positio
Brown Charles D.
Greenhaus Bruce W.
Qualcomm Incorporated
Torres Marcos
Trost William
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