Multiplex communications – Communication over free space – Combining or distributing information via time channels
Reexamination Certificate
1999-05-05
2003-09-02
Appiah, Charles N. (Department: 2682)
Multiplex communications
Communication over free space
Combining or distributing information via time channels
C370S337000, C370S345000
Reexamination Certificate
active
06614777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Method and system for the configuration of a radio interface between a mobile station and a base station in a time-division multiplex mobile radio system for packet data transmission.
2. Description of the Prior Art
Connection-oriented concepts and concepts based on logic links may be used to transmit data between two communications terminals. In the case of connection-oriented data transmissions, physical resources must be provided between the two communications terminals throughout the entire time of data transmission.
The permanent provision of physical resources is unnecessary for data transmission via logical links. One example of such data transmission is packet data transmission. In this case, a logic link exists between the two communications terminals throughout the entire duration of data transmission, but physical resources are provided only during the actual transmission times for the data packets. This method is based on the fact that the data is transmitted in short data packets, between which relatively long pauses may occur. In the pauses between the data packets, the physical resources are available for other logic links. A logic link results in a saving of physical resources.
The packet data transmission method known from German Patent Specification DE 44 02 930 A1 can be used, in particular, for communications systems with limited physical resources. For example, in mobile radio systems such as the GSM mobile radio system (Global System for Mobile Communications), the physical resources in the frequency band, including the number of frequency channels and time slot, are limited and must be used economically.
The GSM mobile radio system is one example of a time-division multiplex mobile radio system in which time slots within a frequency channel can be split between different communications terminals. The radio station at the network end of a mobile radio network is a base station which communicates with mobile stations via a radio interface. Transmission from a mobile station to the base station is called the uplink direction and transmission from the base station to a mobile station is called the downlink direction. A channel, which is reserved for packet data transmission, is formed by at least one time slot per time-division multiplex frame. Furthermore, the channel is defined by the carrier frequency and any frequency jump sequence.
The GSM mobile radio system was originally conceived for voice transmission wherein one channel was reserved for continuous information transmission between the mobile station and the base station. However, for packet data transmission, a common channel is used for packet data transmission for a plurality of mobile stations. In addition to the packet data, signalling information is also transmitted, for which a time slot is provided at cyclic intervals within the channel.
The distinction between logic links and physical connections also means that, although a logic link exists for a mobile station, no packet data is transmitted over a certain time interval. However, as long as there is no transmission from the mobile station to the base station, it is impossible for the base station to carry out any measurements relating to the transmission conditions from the mobile station. Previously calculated values lose their validity and must be redefined during renewed allocation of physical channels, or the base station must ensure that the transmission conditions are set in such a manner that reliable transmission is possible in every case. The latter leads, for example, to an excessive, or even maximum, transmission power setting.
Accordingly, the present invention is based on the object of specifying a method and a system for configuration of a radio interface for packet data transmission, wherein the time delay for passing through a configured radio interface between a mobile station and a base station is reduced.
SUMMARY OF THE INVENTION
A method according to the present invention for configuration of the radio interface combines a plurality of time slots for signalling within the channel for packet data transmission to form a signalling block. In this case, the time slots need not belong to immediately successive frames. Such a signalling block is particularly important for the downlink direction since it contains information for configuration of the radio interface for the mobile stations; for example, the transmission level and the timing advance. The combination of time slots to form a signalling block results in the time duration to completion of the signalling block at the receiving end being minimal. The mobile stations are, in consequence, quickly supplied with the information required for configuration of the radio interface. Signalling to the plurality of mobile stations is possible via one signalling block.
The combination of the configuration data in a message saves transmission capacity, which is now available for adjacent cell measurements or other signalling information.
The allocation is advantageously independent of packet data transmission from or to the mobile station. As a result of this fixed allocation of a time slot for signalling, even to mobile stations to which no physical channel is currently allocated, the base station can carry out continuous measurements with regard to the radio interface. When packet data transmission resumes, immediately valid measurements are made available for configuration of the radio interface.
According to an alternative embodiment of the present invention, a plurality of successive time slots for packet data transmission in the channel are also combined to form a packet data block. Since information from a plurality of time slots first forms a packet data block, it is possible to interleave the information of a packet data block and to simplify reconstruction of the information. The interleaving can also be applied to the signalling data.
The configuration data for a mobile station can, in this case, be transmitted together with the configuration data for other mobile stations in a single time slot for signalling in the downlink direction. In this case it is advantageously repeated or provided with a coding or error detection, or in a plurality of non-successive time slots for signalling being transmitted. In the latter case, the interleaving provides error protection. It is possible to set the time slots which are combined to form such a signalling block. In the case of such use, for example, of every other time slot for signalling, the time slots in between can be used for adjacent cell measurements.
The proportion of time slots for adjacent cell measurements can be further increased if less configuration data is transmitted (for example, only the timing advance) or only a small number of mobile stations need to be supplied. In this case, cyclic adaptation of the combination sequence may be provided. Such adaptation improves the matching of the signalling complexity to the actual requirements of the mobile stations for packet data transmissions.
According to the present invention, a closed control loop for the timing advance can be achieved since time slots for signalling are allocated to mobile stations in the uplink direction, and signalling blocks for the mobile stations arrive, with a short time delay, in the downlink direction. Advantageously, only the mobile station and the base station are involved in this control loop. Since, in contrast to packet data transmission, no specific arrangement is required between a mobile station and a data block for this signalling (this is normally carried out in a base station controller), the base station can set the timing advance on its own. In this case, there is no signalling complexity between the base station and the base station controller.
The configuration of the timing advance and the transmission power setting are carried out independently of one another, according to a further refinement of the present invention. The timing advance is defined by a closed control lo
Menzel Christian
Öttl Martin
Appiah Charles N.
Siemens Aktiengesellschaft
Staas & Halsey , LLP
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