Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
2000-07-07
2004-04-27
Maung, Nay (Department: 2684)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S069000, C370S321000, C370S902000, C370S522000
Reexamination Certificate
active
06728550
ABSTRACT:
The present invention relates to a base station for communicating with one or more mobile terminals of a wireless radio communication system, to a mobile terminal for communicating with a base station of a wireless radio communication system and a communication method for the communication between a base station and one or more mobile terminals of a wireless radio communication system. Particularly, the present invention relates to the power control of downlink information transmitted from a base station to one or more mobile stations in a short range wireless local area network.
In certain wireless local area communication systems as the proposed ETSI BRAN Hiperlan 2 system proposed for a short range wireless communication, as for example having a transmission range of 50 m to 100 m, a downlink slow or semistatic power control is used for the transmission of downlink information in order to reduce interference to neighbouring cells and systems. In the paper HL 13.5 ERI
2
a of May 12, 1999 for the planned ETSI BRAN standard, several proposals are disclosed for such a slow or a semistatic power control. In a wireless local area communication systems, as the proposed ETSI BRAN Hiperlan
2
system, user and control data are transmitted in so-called medium access control (MAC) frames. A MAC frame is a basic transmission frame and contains for example a broadcast control channel (BCCH), a frame control channel (FCCH), downlink data, uplink data and a random access channel (RACH). It is to be noted that the above specified communication system is a time division duplex (TDD) system, in which uplink and downlink transmission of user data is possible within one MAC frame. However, the present invention also relates to wireless radio communication systems in which the basic transmission frames or MAC frames only comprise either downlink or uplink data, as e. g. in a FDD system. Downlink transmission is the transmission of user or control data between a base station, also called access point or central control station, and one or more mobile terminals of the wireless communication system. Mobile terminals in the present context are all devices being dependent on or being controlled by a base station, e. g. in a Master-Slave relationship. The word “mobile” has been chosen to indicate that this kind of device may be freely moved within the transmission range of a respective base station. Uplink transmission is the transmission of user and control data from a mobile terminal to the corresponding base station. The communication system is a wireless radio communication system, in which signals are transmitted in the radio range, as for example the GHz range.
In the above-mentioned ETSI BRAN paper, several possibilities of a power control for the downlink transmission are described in order to avoid interference with other cells of the communication system or with other communication systems. One possibility is to assign downlink transmitter power independently to each mobile terminal communicating with the respective base station. This requires a complex design of the base station, since the transmitter power has to be changed several times during the downlink phase of one MAC frame duration. Additionally, the mobile terminals have to measure the received transmission power and communicate corresponding information to the base station. Since it is proposed to use the same downlink transmission power for all mobile terminals, the transmission power should be chosen so that all mobile terminals in one cell have sufficient reception.
In this case, one possible solution is to transmit the BCCH and the FCCH with a fixed power and to apply power control only to the rest of the downlink data transmitted in one MAC frame. Thereby, provisions have to be made in the base station in order to change the transmission power within one MAC frame and the automatic gain control in the receiving mobile terminals must be quite complex, since it has to be able to cope with the fast changes in the received transmission power between the BCCH/FCCH and the user data within a MAC frame. This proposal therefore leads to a high circuit complexity and a high power consumption on both sides, i.e. the base station and the mobile terminals, particularly since in all MAC frames the BCCH/FCCH and the user data are transmitted with different transmission powers.
A second proposed possibility is to use the same downlink transmission power in the entire MAC frames, i.e. power control is applied to the BCCH/FCCH as well as the downlink user data. Thereby, the mobile terminals within one cell communicating with a base station have to measure the received downlink transmission power and send corresponding information to the base station. On the basis of the received information the base station sets the downlink power control so that the mobile terminal having the worst reception still receives the downlink information with a sufficient quality. This possibility, however, has the disadvantage that the effective cell size is reduced to the actual active (communicating) mobile terminals. Since the effective cell size is limited, new mobile terminals can only gain access to the base station if they are within this limited coverage range.
The object of the present invention is therefore to provide a base station, a mobile terminal and a communication method of a wireless radio communication system of the above-mentioned type, which support a transmission power control of downlink information without limiting the transmission range only to currently active mobile terminals.
This object is achieved by a base station for communicating with one or more mobile terminals of a wireless radio communication system according to claim
1
, with transmitting means for transmitting information in medium access control frames of said communication system, power control means for controlling the transmission power of the transmitting means so that the transmission power of at least a broadcast control channel and a frame control channel in a respective medium access control frame is increased after certain time intervals to an increased transmission power level as compared to the transmission power level of other medium access control frames (namely the downlink sections thereof) transmitted during the time intervals.
The above object is further achieved by a mobile terminal for communicating with a base station of a wireless radio communication system according to claim
12
, with receiving means for receiving information in medium access control frames of said communication system, processing means for processing received information, adjusting means for adjusting the processing means to the transmission power of the received information, whereby the transmission power of at least a broadcast control channel and a frame control channel in a respective medium access control frame is increased after certain time intervals to an increased transmission power level as compared to the transmission power level of other medium access control frames (namely the downlink sections thereof) transmitted during said time intervals.
The above object is further achieved by a communication method for the communication between a base station and one or more mobile terminals of a wireless radio communication system according to claim
22
, whereby information is transmitted and received in medium access control frames of the communication system, and whereby the transmission power of at least a broadcast control channel and a frame control channel in a respective medium access control frame is increased after certain time intervals to an increased transmission power level as compared to the transmission power level of other medium access control frames (namely the downlink sections thereof) transmitted during the time intervals.
It is to be noted that a medium access frame of the wireless radio communication system in the context of the present invention is a basic transmission frame comprising control and user data exchanged between a base station and a mobile
Böhnke Ralf
Dölle Thomas
Konschak Tino
Frommer William S.
Frommer & Lawrence & Haug LLP
Gantt Alan T.
Maung Nay
Smid Dennis M.
LandOfFree
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