Multiplex communications – Diagnostic testing – Determination of communication parameters
Reexamination Certificate
1998-10-29
2001-09-18
Nguyen, Chau (Department: 2739)
Multiplex communications
Diagnostic testing
Determination of communication parameters
C455S069000, C455S522000
Reexamination Certificate
active
06292471
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of European Patent Application No. 97308744.8, which was filed on Oct. 31, 1997.
BACKGROUND OF THE INVENTION
1. Field of The Invention
This invention relates to power control mechanisms for controlling signal strength in a Mobile Wireless Commination System, and in particular to the initial power at which signals to and from mobile end-user devices and a fixed base station should be transmitted.
2. Description of Related Art
In existing systems, a mobile end-user device seeking to initiate communication with a base station broadcasts a request signal at increasing power levels until acknowledged by the base station. Likewise, a base station pages a mobile end-user device at increasing power levels until the end-user device responds. In each situation, one broadcasting station in the communication system ramps the power until a reasonable SNR is achieved by the second receiver. This ramping of power can lead to a signalling exchange procedure which can take sometime, since typically each station is broadcasting over a different channel (particularly in cellular radio telephone systems). It can also lead to interference between mobile end-user devices and to a loss of signal quality of other users of the wireless communication system.
EP 682418 A2 describes a fast, closed loop power control for a mobile radio telecommunication system, which is directed to the steady state operation of closed loop power control. Such a system is common in “second generation” systems, which are circuit switched wireless communication systems. A closed loop functions only if both transceivers in a wireless communication link are already synchronised and exchanging information. The power control algorithm makes use of this established bi-direction link, to exchange information on power levels. The received power is measured and the information fed back to the transmitter, allowing it to adjust its power level to an optimal value.
Future wireless communications systems will support a wide range of services including packet services and, therefore, are likely to be highly dynamic. Thus, the initial set up will be increasingly important, as compared with the steady state, and reasonable power levels must be reached immediately. There is thus a need for power control mechanisms between stations in a mobile wireless communication system which functions at start up and which decreases the time taken to establish an efficient power level.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method of establishing initial power control between a first and second station in a mobile wireless communication system comprising:
transmitting from a first station a first set-up signal over a first channel within said communication system;
receiving said first signal at a second station and transmitting, in response, a second signal over a second channel within said communication system;
receiving said second signal, at said first station, and transmitting, in response, a third signal; and comprising
said second signal includes a measure of the Signal-to-Interference ratio (SIR) of said first signal as received at said second station
and further comprising
the power of said third signal is adjusted, in response to the SIR measure included in said second signal.
According to a second aspect of the invention there is provided apparatus for establishing initial power control between a first and second station in a mobile wireless communication system comprising:
a first station in the communication system, having a transmitter for transmitting a first set-up signal over a first channel within the communication system;
a second station in the communication system, having a receiver for receiving the first signal and a transmitter for transmitting a second signal over a second channel within the communication system;
said first station having a receiver for receiving said second signal;
wherein a third signal is transmitted in response to said second signal; and
comprising
said second station includes means to measure the Signal-to-Interference ratio (SIR) of the first signal as received at said second station and to include the SIR measure in said second signal and further comprising
said first station includes means to adjust the power of the third signal, in response to the SIR measure included in said second signal.
The third signal may include a measure of the SIR of the second signal, as received at the first station. The second station may include means to adjust the power of subsequent signals transmitted by the second station. The third signal may be transmitted over a third channel in the communication system.
The stations may broadcast additional signals over the first, second or third channels or over additional channels in the communication system. The first station may be a base station and the first channel may be a broadcast control channel (BCCH) over which a constant information signal is broadcast (the first signal). The second station may be a mobile end-user station and the second channel may be a random access channel (RACH) over which the mobile station transmits request to transmit signals (the second signal). The third signal may be a RACH request acknowledgement (RA Ack), broadcast by the base station over an associated control channel (FACH), the third channel.
Alternatively, the first channel may be a paging channel (PCH) over which the base station pages (with the first signal) the mobile station. The mobile station may respond with a page acknowledgement (Page Ack) over the random access channel (the second signal and the second channel, respectively). The base station may then respond to the Page Ack by transmitting data (the third signal) over the traffic channel (TCH), the third channel.
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European Search Report, Mar. 26, 1998.
Cao Qiang
Freiberg Lorenz Fred
Reader David Jonathan
Lucent Technologies - Inc.
Nguyen Chau
Nguyen Phuongchau Ba
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