WO1999027655A2

WO1999027655A2 - Method for connection establishment, and transceiver

Info

Publication number: WO1999027655A2
Application number: PCT/FI1998/000863
Authority: WO
Inventors: Jukka Jokinen; Peter Muszynski
Original assignee: Nokia Networks Oy
Priority date: 1997-11-06
Filing date: 1998-11-05
Publication date: 1999-06-03
Also published as: AU1035399A; FI106833B; FI974154A0; WO1999027655A3; FI974154A

Abstract

The invention relates to a method for connection establishment and a transceiver used in a TDMA cellular radio system and comprising at least two transceivers which establish a connection with each other by means of an information signal. The transceiver comprises modulating means (123), which modulate the information signal to a carrier, and transmission means (126), which place the modulated information signal into a time slot of the carrier and transmit the information signal in the modulated carrier to provide a signal establishing a connection. The transmission means (126) establish substantially simultaneous connections to one and the same or to separate transceivers by transmitting the carriers interleaved in the time slots, and the modulating means (123) modulate each information signal that establishes a connection by means of a dedicated carrier, before the information signal is transmitted.

Description

METHOD FOR CONNECTION ESTABLISHMENT, AND TRANSCEIVER

FIELD OF THE INVENTION

The invention relates to a connection establishment method used in a cellular radio system applying a TDMA multiple access method, the cellular radio system comprising at least two transceivers, connections between the transceivers being established by means of an information signal which is modulated to a carrier, the modulated carrier being arranged into a time slot, and the information signal being transmitted on the carrier to provide a signal establishing the connection. BACKGROUND OF THE INVENTION

The invention is suitable for cellular radio systems, particularly for GSM and DCS systems (GSM = Global System for Mobile Communication, DCS = Digital Cellular System), in which TDMA multiple access method is used (TDMA = Time Division Multiple Access). Multiple access is provided by arranging a plural number of carriers available for use, one carrier having eight simultaneous users, for example. To enable the signals of the eight users to be separated from one another, they are transmitted as bursts in predetermined time slots. In other words, a particular transceiver transmits only at a particular time instant. The time slots of the eight users form a frame, and by repeating the frame, even a large amount of data can be transmitted.

According to prior art, a subscriber terminal, such as a mobile phone, can establish a connection for example to a base station to which the the subscriber terminal has had the best connection, the subscriber terminal having established the connection by using one carrier. In prior art solutions, different time slots have equal resources.

A prior art subscriber terminal does not allow, for example, a speech connection to another subscriber terminal and a substantially simultaneous, high bit-rate connection to a data server, such as a VWWV- server (WWW = World Wide Web). In this context, 'substantially simultaneous connections' refer to connections in which bursts are transmitted after a period of time of the order of a GSM time slot from the transmission of another connection's burst. CHARACTERISTICS OF THE INVENTION

An object of the present invention is thus to provide a solution in which connections are established which are simultaneous from the user's point of view and the data transmission resources of which can differ from one another.

This is achieved with a method of the invention described in the preamble, characterized in that substantially simultaneous connections to one and the same or to different transceivers are established by transmitting the carriers interleaved in the time slots; and each information signal establishing a connection is modulated by means of a dedicated carrier.

The invention also relates to a transceiver used in a TDMA cellular radio system comprising at least two transceivers which establish a connection between each other by means of an information signal, the transceiver comprising modulating means which modulate the information signal to a carrier wave, and transmission means which place the modulated carrier to a time slot and transmit the information signal on the modulated carrier to provide a signal establishing a connection. The transceiver is characterized in that the transmission means establish substantially simultaneous connections to one and the same or to different transceivers by transmitting the carriers interleaved in the time slots, and that the modulating means modulate each information signal establishing a connection by means of a dedicated carrier, before the information signal is transmitted.

The method and transceiver of the invention provide considerable advantages compared with previous solutions. The method involves transmitting and receiving signals which are each modulated by means of a dedicated carrier. Overlapping transmission and reception of signals is prevented by means of time synchronization of signals and suitably selected time slots. The user of a subscriber terminal of the invention can have substantially simultaneous connections to a plural number of different destinations. In addition, the resources of the connections can differ from one another. Consequently, a mobile phone user, for example, can have a speech connection and a substantially simultaneous data transmission connection, for example, functioning at a high bit-rate. DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail with reference to examples illustrated in the accompanying drawings, in which Figure 1 is block diagram illustrating a schematic structure of a transceiver of the invention; Figure 2 illustrates a cellular radio system in which a method of the invention is used; and

Figure 3 illustrates, in greater detail, a signal establishing a connection between two transceivers. DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 illustrates the essential parts of a transceiver of the invention. More specifically, the Figure illustrates a structure of a subscriber terminal 100 functioning as a transceiver. The subscriber terminal can be a mobile phone, for example. The subscriber terminal 100 comprises a receiver part and a transmitter part. The receiver part comprises a receiving antenna 111 , radio frequency parts 112, demodulating means 113, a decoder 114 and an information source 115, such as an earpiece.

The transmitter part comprises an information source 121 , a coder 122, modulating means 123, radio frequency parts 124 and a transmitting antenna 125. The information source 121 can be a microphone, for example. The subscriber terminal 100 further comprises control means 131 , which are shared by the receiver part and the transmitter part. In practice, a signal is transmitted and received via one and the same antenna. The subscriber terminal 100 further comprises signal reception means 116 and signal transmission means 126.

The receiver part of the subscriber terminal 100 shown in Figure 1 operates as follows. The radio frequency parts 112 of the subscriber terminal 100 shift a radio-frequency analog signal transmitted by the antenna 111 to an intermediate frequency and filter the signal. The radio frequency parts 112 also detect the intermediate-frequency signal. The demodulation means 113 restore a broadband signal to a narrow-band data signal. The data signal is decoded in a suitable manner in the decoder 114.

The decoder 114 typically decodes a convolution coded signal. The decoder 114 usually also decrypts and demultiplexes a pre-treated signal. From the decoder 114, the signal is transferred further to the information source 115. The signal received by the antenna 111 is also transferred to the reception means 116. The reception means 116 receive substantially simultaneously a plural number of information signals on the carriers. The functions of the reception means 116 are arranged, in practice, in the demodulation means 113 and the radio frequency parts 112.

The transmitter part of the subscriber terminal 100 functions as follows. The information source 121 receives an audio signal and transmits to the coder 122 an electronic response to the signal. The coder 122 convolution- codes and typically encrypts the signal. In addition, the coder 122 multiplexes the bits or bit groups of the signal. The signal is then converted into radio frequency, in a prior art manner, in the radio frequency parts 124, and transmitted via the antenna 125 to the radio path.

The transmission means 126 transmit substantially simultaneously a plural number of information signals on the carriers. The functions of the transmission means 126 are arranged, in practice, in the modulating means 123 and in the radio frequency parts 124. The control means 131 control the functions of both the transmitter and the receiver part.

The transmission means 126 of the subscriber terminal 100 transmit substantially simultaneously the information signals modulated by different carriers and arranged into time slots. The transmission means 126 transmit only one time slot at a time because simultaneous transmission of the time slots is prevented. Simultaneous transmission of the time slots is prevented by means of synchronization. The reception means 116 of the subscriber terminal 100 receive substantially simultaneously the time slots modulated by a plural number of different carriers. The reception means 116 thus preferably demodulate each time slot establishing a connection by means of a dedicated carrier. The radio frequency parts 112 are able to process a signal arranged in the time slots because simultaneous arrival of time slots to the reception means 116 is prevented, the prevention being carried out by means of time synchronization. Figure 2 illustrates a cellular radio system using the method of the invention. The cellular radio system comprises a plural number of subscriber terminals 100 and base stations 200, 201 , 202. The subscriber terminals 100 and the base stations function as transceivers. In a solution according to Figure 2, the subscriber terminal 100 uses a signal 150 to establish a connection to the base station 200. The signal 150 is formed of time slots comprising information signals, the time slots being transmitted at different intervals. Before the signal 150 is sent, it is modulated to a carrier. The subscriber terminal 100 also uses a signal 250 to establish a connection to the base station 201. For the user of the subscriber terminal 100, the connections established by means of the signal 150 and signal 250 are substantially simultaneous. The transmission means 126 transmit the signals 150, 250 modulated by means of dedicated carriers. The modulated carriers may differ as to their resources, the carriers being thereby capable of conveying different amounts of user information. The subscriber terminal 100 can also establish substantially simultaneous connections to the base station 200, for example. The base station receives the signal sent by the subscriber terminal

100 and the reception means 116 of the base station demodulate the signal they receive. The reception means 116 are, in practice, arranged in the demodulation means 113. The base stations 200, 201 , 202 and the subscriber terminals 100 are time-synchronized in such a way that the time slots do not overlap, in the solution of the Figure, for example, the base stations are synchronized by supplying a synchronizing signal to the base stations 200, 201 , 202 via the PSTN network.

The subscriber terminals 100 are synchronized by means of the synchronizing signals transmitted by the base stations. In a solution according to Figure 2, the signal 150 can be a carrier of the GSM system, for example. The signal 250 can be a UMTS (UMTS = Universal Mobile Telecommunication System) carrier, for example.

The subscriber terminal 100 shown in Figure 2 can establish a plural number of connections to the separate base stations 200, 201 , 202, the connections being, from the user's point of view, substantially simultaneous. The connections can also be modulated by means of one and the same carrier. The subscriber terminal 100 can establish a connection to a particular base station by using signals modulated by different carriers. If the connections established by the subscriber terminal 100 are modulated by means of one and the same carrier, the advantages provided by differing resources are, however, not obtained.

In Figure 3 the subscriber terminal 100 transmits to the base station 200 at least two TDMA signals 1 ,2, the time slots of which comprise information signals. The signals 1 and 2 can be transmitted either to one and the same base station or to separate base stations. In the solution shown in the Figure, the subscriber terminal 100 transmits a signal in TDMA signal time slots TS3 and TS7. In addition, the subscriber terminal 100 transmits a signal in TDMA signal time slots TS1 and TS5.

The time slots are selected so that time slots comprising information signals modulated by means of a carrier having one and the same frequency do not overlap when carriers are transmitted. The overlapping of the time slots is prevented by means of a suitable time synchronization. In addition, in the solution shown in the Figure, the signals of the time slots TS3, TS7 of a TDMA signal 1 and those of the time slots TS1 , TS5 of a TDMA signal 2 are each modulated by means of a dedicated carrier. The transmission means 126 thus modulate each time slot establishing a connection by means of a dedicated carrier. The carriers can differ from one another as regards their resources, which means that the carriers can transmit different amounts of information.

The transmission means 126 can establish substantially simultaneous connections to one and the same transceiver or to different transceivers by transmitting the carriers interleaved in the time slots. Interleaving is preferably carried out in such a way that the carrier frequencies used for modulating the information signals in consecutive time slots differ from one another. In addition, before an information signal is transmitted, the modulating means 123 modulate each information signal that establishes a connection by means of a dedicated carrier. The modulating means 123 can make the carriers hop according to a predetermined frequency sequence. If the hopping of the carriers is prevented, the modulating means modulate the carriers by a predetermined frequency.

The reception means 116 of the transceiver receive substantially simultaneously information signals which are each modulated by means of a dedicated carrier. After an information signal is received, the demodulating means 113 demodulate each information signal establishing a connection by means of a dedicated carrier. The interleaving of the carriers allows the subscriber terminal 100 to use a particular time slot to transmit an information signal modulated by means of a particular carrier to the base station. In the next time slot the subscriber terminal 100 can transmit an information signal modulated by means of another carrier to the same or to a different base station.

Although the invention is described above with reference to examples shown in the accompanying drawings, it is apparent that the invention is not restricted to them, but can be varied in many ways within the scope of the inventive idea disclosed in the attached claims.

Claims

1. A connection establishment method used in a cellular radio system applying a TDMA multiple access method, the cellular radio system comprising at least two transceivers, connections between the transceivers being established by means of an information signal which is modulated to a carrier, the modulated carrier being arranged into a time slot, and the information signal being transmitted on the carrier to provide a signal establishing the connection, characterized in that substantially simultaneous connections to one and the same or to different transceivers are established by transmitting the carriers interleaved in the time slots; and each information signal establishing a connection is modulated by means of a dedicated carrier.

2. A method according to claim 1, characterized in that the information signals of consecutive time slots are modulated by means of different carriers.

3. A method according to claim 1, characterized in that the carriers are made to hop at a predetermined frequency sequence.

4. A method according to claim 1, characterized in that, if the hopping of the carriers is prevented, a carrier is transmitted at a specific frequency.

5. A method according to claim 1, characterized in that the information signals modulated by means of dedicated carriers are transmitted at different times on the time domain.

6. A method according to claim 1, characterized in that each information signal arranged into a time slot is modulated by means of a dedicated carrier.

7. A method according to claim 1, characterized in that the carriers can have similar or differing data transmission resources.

8. A method according to claim ^ characterized in that the information signals establishing a connection and arranged into time slots are each modulated by means of carriers ofthe same or a different frequency.

9. A method according to claim 1, characterized in that the signals to be transmitted are time-synchronized in order to prevent overlapping transmission and reception ofthe modulated signals.

10. A method according to claim 1, characterized in that the carriers are transmitted interleaved in time slots, the carrier frequencies used in consecutive time slots being different from one another.

11. A transceiver used in a TDMA cellular radio system and comprising at least two transceivers which establish connections between each other by means of an information signal, the transceiver comprising modulating means (123) which modulate the information signal to a carrier, and transmission means (126) which place the modulated carrier into a time slot and transmit the information signal on the modulated carrier to provide a signal establishing a connection, characterized in that the transmission means (126) establish substantially simultaneous connections to one and the same or to different transceivers by transmitting the carriers interleaved in the time slots; and that the modulating means (123) modulate each information signal that establishes a connection by means of a dedicated carrier, before the information signal is transmitted.

12. A transceiver according to claim 11, characterized in that the modulating means (123) modulate the information signals of consecutive time slots by means of different carriers.

13. A transceiver according to claim 11, characterized in that the transceiver comprises reception means (116) receiving substantially simultaneously information signals which are each modulated by means of dedicated carriers.

14. A transceiver according to claim 11, characterized in that the transceiver comprises demodulating means (113), which demodulate each information signal establishing a connection by means of a dedicated carrier.

15. A transceiver according to claim 11, characterized in that the modulating means (123) make the carriers hop at a predetermined frequency sequence.

16. A transceiver according to claim 11, characterized in that, in case the carriers cannot be made to the hop to a predetermined frequency sequence, the transmission means (126) transmit a carrier at a specific frequency.

17. A transceiver according to claim 11, characterized in that, the transmission means (126) transmit the information signals modulated by the modulating means (123) at different times on the time domain.

18. A transceiver according to claim 11, characterized in that the modulating means (123) modulate each information signal placed in a time slot by means of a dedicated carrier.

19. A transceiver according to claim 11, characterized in that the transmission means (126) transmit the carriers interleaved in the time slots, the frequencies of the carriers used for modulating the information signals of consecutive time slots differing from one another.

20. A transceiver according to claim 11, characterized in that the transmission means (126) transmit carriers of differing data transmission resources.

21. A transceiver according to claim 11, characterized in that the modulating means (123) modulate each of the information signals placed in the time slots and establishing a connection by means of carriers of the same or a different frequency.

22. A transceiver according to claim 11, characterized in that the transmission means (126) time-synchronize the information signals to be transmitted, in order to prevent overlapping transmission and reception of the modulated signals.

23. A transceiver according to claim 11, characterized in that the transceiver is a base station or a subscriber terminal, for example.