Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Reexamination Certificate
2000-04-10
2004-01-06
Deppe, Betsy L. (Department: 2734)
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
C375S343000
Reexamination Certificate
active
06674817
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a communication device for transmitting and receiving control and user data bursts in a digital telecommunication system and to a method for distinguishing between data bursts of a first type transmitted from a first communication device and data bursts of a second type different from said first type transmitted from a second communication device in a digital telecommunication system. The communication device of the present invention can be a base station or a mobile terminal of the telecommunication system. The first communication device and the second communication device can be a base station and a mobile terminal, respectively, or two mobile terminals directly communicating with each other. The present invention particularly enables the distinction of the traffic direction of received data bursts.
DESCRIPTION OF RELATED ART
In a digital radio telecommunication system, one base station usually serves and communicates with several mobile terminals or user equipment terminals in predetermined cells. The transmission of data from the base station to the mobile terminals is called downlink and the transmission of data from the mobile terminals to the base station is called uplink. In some telecommunication systems, a direct communication of data bursts between the mobile terminals is possible. The data, which can be either control data or user data, e. g. speech data, are transmitted in data bursts. For the transmission of data bursts, several transmission channels are defined. The transmission channels depend on the particular telecommunication system in use. In each telecommunication system, however, transmission channels for the transmission of synchronization data, control data and user data are necessary. By means of the synchronization data, the mobile terminals synchronize their time frames to the timing of the base stations. The control data channels are e. g. used by the base stations to transmit broadcast control data to all mobile terminals in the respective cell. The synchronization channel can be part of a control channel, for example the broadcast control channel. The data channels are used by the mobile terminals to transmit user data to the base stations and by the base stations to transmit user data to the mobile terminals.
An example of the time frame structure of a media access control channel (MAC) comprising the most common channels is shown in FIG.
1
. The MAC frame structure shown in
FIG. 1
comprises a control channel, e. g. a broadcast control channel (BCCH) used by the base stations to broadcast control data to all mobile terminals in the respective cells, traffic channels for uplink or downlink transmission of user data and a random access channel (RACH). The random access channel is used by the mobile terminals to transmit service requests to the base stations. E. g. if a mobile terminal needs a user data channel for transmitting user data to a base station, the mobile terminal sends a service request via the random access channel to the base station. The base station receiving the service request answers the request by sending a corresponding grant or refusal message back to the mobile terminal.
As shown in
FIG. 1
, the different channels comprise training sequences, preambles and/or headers. Training sequences or synchronization headers are mainly used for an accurate synchronization of the receiving unit, i. e. a base station or a mobile terminal receiving data bursts on a transmission channel to enable a reliable reception and use of the transmitted data. E. g., a training sequence consists of a predetermined number of repetition patterns or symbols, whereby each symbol consists of a certain number of samples. Typically, all symbols or repetition patterns in a given training sequence are identical, i.e. have the same shape or content.
Looking at the example of the GSM-system (global system for mobile communications), the normal user data bursts, the synchronization bursts and the random access bursts each comprise a training sequence. In the normal user data burst, the training sequence is located in the middle of a time slot and comprises 26 bits. In a synchronization burst the training sequence is also located in the middle of a time slot, but comprises 64 data bits. In a random access burst, the training sequence is located in the front part of the time slot and comprises 41 bits. In this case, a communication device receiving different types of data bursts can easily distinguish the different types of data bursts by their different training sequences and downlink and uplink data bursts can be recognized without problems. A mobile terminal therefore can distinguish easily between a broadcast control data burst broadcast from a base station to all mobile terminals in the corresponding cell and user data bursts or random access bursts transmitted from other mobile terminals to the base station. However, the use of training sequences of different length or shapes for the different types of data bursts requires a complex detector structure in the receiving unit, because the receiving unit has to deal with many different types of training sequences.
Depending on the multiple access scheme used in the telecommunication system, e. g. frequency division multiple access, time division multiple access or code division multiple access, a mobile terminal may have other criteria, e. g. frequency or code, available to distinguish if the data bursts have been transmit from a base station or from other mobile terminals. In this case, even the use of identical training sequences in the different types of data bursts may be possible. However, if no other criteria are available, as e. g. in a time division duplex mode (TDD mode), in which the same carrier frequency is used, a mobile terminal cannot distinguish if the data bursts are coming from a base station of from other mobile terminals when identical training sequences are used in the different data bursts.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide a communication device for transmitting and receiving control and user data bursts in a digital telecommunication system, which is able to distinguish between different types of data bursts in an easy and simple way. The object of the present invention is further to provide a method for distinguishing between data bursts of first type transmitted from a first communication device and data bursts of a second type different from said first type transmitted from a second communication device in a digital telecommunication system.
The above object is achieved by a communication device for transmitting and receiving control and user data bursts in a digital telecommunication system according to claim 1, which comprises receiving means for receiving data bursts including data bursts of a first type and data bursts of a second type different from said first type, said first type bursts respectively comprising a first training sequence and said second type bursts respectively comprising a second training sequence. The communication device further comprises correlation means for auto-correlating the data of received data bursts and outputting an auto-correlation result and recognizing means for recognizing the type of a received data burst on the basis of a phase value of the auto-correlation result of the training sequence of said burst. A communication device of the present invention can be a mobile terminal or a base station of the telecommunication system.
The above object is further achieved by a method for distinguishing between data bursts of a first type transmitted from a first communication device and data bursts of a second type different from said first type transmitted from a second communication device in a digital telecommunication system, said first type data bursts respectively comprising a first training sequence and said second type data bursts respectively comprising a second training sequence, which comprises the steps of receiving a data burst,
Böhnke Ralf
Dölle Thomas
Konschak Tino
Deppe Betsy L.
Frommer William S.
Frommer & Lawrence & Haug LLP
Sony International (Europe) GmbH
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