Power control of remote communication devices

Details Power control of remote communication devices Power control of remote communication devices

1997-10-21

2001-01-02

Eisenzopf, Reinhard J. (Department: 2745)

Telecommunications

Transmitter and receiver at separate stations

Plural transmitters or receivers

C455S127500

Utility Patent

active

06169907

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to apparatus and methods for improving cellular communication networks. More particularly, the present invention relates to improved base transceiver station (BTS) architectures in a cellular communication network.
Cellular communication systems are well known in the art. In a typical cellular communication system, the mobile stations (MS's) may transmit and receive voice and/or data with the cellular network and one another utilizing radio waves. To facilitate discussion,
FIG. 1
depicts the architecture of a cellular communication network
100
that implements the well known Global System for Mobile Communication (GSM) standard. Although the GSM cellular network is chosen herein for illustration purposes, it should be borne in mind that the invention disclosed herein is not limited to any particular standard.
In
FIG. 1
, there is shown a plurality of mobile stations (MS's)
102
,
104
, and
106
, representing the mobile interface with the cellular users. In a typical network, MS's
102
,
104
and
106
may be, for example, mobile handsets or fixed mobile stations mounted in vehicles. MSs
102
,
104
, and
106
typically include radio and processing functions for exchanging voice and data via radio waves with transceivers (TRX's) in base transceiver stations (BTS's)
114
and
116
. The transceivers (TRX's) are shown in
FIG. 1
as transceivers
114
a
,
114
b
,
114
c
,
116
a
, and
116
b
. The BTS's may be thought of, in one sense, as the counterpart to the MS's within the cellular network, and its main role is to connect the mobile stations with the rest of cellular communication network
100
.
There is also shown in
FIG. 1
a base station controller (BSC)
118
, whose function is to monitor and control the BTS's. There may be any number of BSC I
18
in a network, whose responsibility includes, among other responsibilities, radio interface management, e.g., the allocation and release of radio channels and handover management. Mobile Services Switching Center (MSC)
120
controls one or more BSC's
118
and provides the basic switching function within the cellular network, including setting-up of calls to and from the MS's. MSC
120
also provides the interface between the cellular network users (via the BSC and BTS) and external networks (e.g., PSTN or public switched telephone network). The components of GSM cellular network
100
are well known to those skilled in the art and are not discussed in great detail here for brevity's sake. Additional information pertaining to GSM and the cellular networks implementing the GSM standard may be found in many existing references including, for example, Redl, Weber & Oliphant, An Introduction to GSM (Artech House Publishers, 1995).
In the prior art, the radio circuitries of the TRX's are typically implemented such that they co-locate with other circuits of the BTS. By way of example,
FIG. 2
illustrates in greater detail exemplary prior art BTS
114
of
FIG. 1
, including TRX's
114
a
,
114
b
, and
114
c
. As is typical, the antennas of the prior art TRX's co-locate with the BTS such that the BTS defines the cell. Although one antenna is shown to facilitate simplicity of illustration, separate transmit and receive antennas may be provided for each TRX, as is well known. Other major functional blocks of BTS
114
includes ABIS interface
202
, which implements the circuitry necessary for interfacing between BTS
114
and its BSC. CPU circuit
204
implements the call processing functions, including for example LAPDm processing, speech framing, channel coding, interleaving, burst formatting, ciphering, modulation, MS power control and the like. The architecture of the prior art BTS is well known and is not discussed here in great detail for simplicity's sake.
It has been found, however, that the conventional BTS architecture has many disadvantages. By way of example, the integration of the radio circuitries of the TRX's and the processing circuitries of the BTS in one unit results in a complex and maintenance-intensive electronic subsystem. Yet prior art BTS's are often installed in locations selected primarily for optimum radio transmission quality such as on top of buildings and other outdoor structures instead of ease of access. These locations, being exposed to the elements, are typically hostile to the delicate and complex electronic circuits of the prior art BTS. Accordingly, these factors tend to render the installation, maintenance, and upgrade of prior art BTS's difficult and expensive.
The integration of the radio circuitries of the TRX's in the prior art BTS also limits the flexibility with which the cell can be modified to accommodate changes in capacity. In the prior art, the BTS, which contains the co-resident TRX antennas, essentially defines the cell. Although some cell shaping may be accomplished by, for example, employing directional antennas, the cell is more or less limited by the transmit power of the antennas in the BTS. Scaling the transmit power upward increases the cell size at the expense of capacity since the use of larger cells reduces the ability to reuse frequencies among neighboring cells. Increasing the transmit power also increases the amount of heat generated, thereby reducing the reliability of the circuitries in the prior art BTS unless fans and/or additional heat dissipation techniques are employed.
In addition to problems associated with defining a cell, appropriate control of the transmit power of MSs also present a myriad of problems. Ideally, all MSs would transmit at a high enough power providing acceptable signal quality, but low enough where the MSs do not interfere with each other. Thus, upper and lower bounds may be established for the transmit power of the MSs. However, conditions may occur where the transmit power of the MSs fall outside these bounds. Prior art systems have not fully accounted for solving all the situations in which the transmit power of the MSs fall outside the established bounds for transmission.
In view of the foregoing, there are desired improved methods and apparatus for overcoming the disadvantages associated with prior art cellular communication systems.
SUMMARY OF THE INVENTION
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, an improved method and apparatus for controlling the transmit power of a communication device is disclosed.
In one embodiment of the present invention, a first communication device is in communication with a second communication device. The communication may be characterized by a first and a second characteristic that are affected by a transmit power of the first communication device, each characteristic having an upper and a lower bound. If the first characteristic falls below its lower threshold the transmit power of the first communication device is not increased until a predetermined amount of time has expired if the transmit power was previously decreased.
In another embodiment, if the second characteristic falls below its lower threshold the transmit power of the first communication device is not increased until a predetermined amount of time has expired if the transmit power was previously decreased.
In yet another embodiment, if the first characteristic rises above its upper threshold the transmit power of the first communication device is not decreased until a predetermined amount of time has expired if the transmit power was previously increased. In yet another embodiment, if the second characteristic rises above its upper threshold the transmit power of the first communication device is not decreased until a predetermined amount of time has expired if the transmit power was previously increased.
In a further embodiment, the transmit power of the first communication device is delayed from being adjusted to bring the communication within the upper and lower bounds of the first criteria and outside the upper an

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