Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J3/00—Time-division multiplex systems
  • H04J3/16—Time-division multiplex systems in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted
  • H04J3/1682—Allocation of channels according to the instantaneous demands of the users, e.g. concentrated multiplexers, statistical multiplexers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2643—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using time-division multiple access [TDMA]
  • H04B7/2646—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using time-division multiple access [TDMA] for broadband transmission
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
  • H04L5/1469—Two-way operation using the same type of signal, i.e. duplex using time-sharing

Definitions

• the invention relates to a data transmission method in a digital radio system where data between two transceivers is transmitted in both directions on the same frequency band in frames consisting of time slots, and where time slots assigned to different directions of transmission are separated from one another in the time domain.
• a previously known solution to the above problem is to form a data transmission frame comprising time slots of different length.
• a user needing more transmission capacity is assigned a longer time slot in both directions of transmission, whereas a user needing less transmission capacity is assigned a shorter time slot in both directions of transmission.
• the drawback of the method is that the time slots of the frame are of a predefined length, and if not much data transmission capacity is needed, bandwidth is unnecessarily wasted in long time slots.
• the object of the present invention is to provide a data transmission method and system in which a bandwidth assigned to the system can be divided according to the need flexibly and more effectively than before. Another object of the invention is to allow effective use of many-sided data transmission services in radio systems without that bandwidth is wasted.
• the object is achieved by a method as described in the introduction, the method being characterized in that the number of time slots assigned to the different directions of transmission is varied dynamically according to the capacity needed in the different directions of transmission.
• Yet another object of the invention is to provide a digital radio system which comprises at least one base station and a number of terminal equipments, and in which data between the base station and the terminal equipments is transmitted in both directions on the same frequency band in frames consisting of time slots, and in which the time slots assigned to the different directions of transmission are separated from one another in the time domain.
• the radio system according to the invention is characterized in that the number of time slots assigned to the different directions of transmission on each frequency band can be varied dynamically according to the capacity needed in the different directions of transmission.
• the solution of the invention has several advantages.
• the number of time slots is varied according to the amount of capacity needed in the different directions of transmission. Consequently, the bandwidth available can be used as effectively and flexibly as possible.
• the solution allows the use of high data transmission capacity requiring services (e.g. video calls) in systems where the bandwidth is limited.
• fig. 1 shows a radio system in which the invention can be applied
• fig. 2 shows a frame of the DECT system
• fig. 3a shows a solution according to the invention for dividing the frame between different directions of transmission
• fig. 3b shows a solution according to the invention in connection with the DECT system.
• the method and receiver according to the invention can be applied in any digital radio system whatsoever where the directions of transmission are on the same frequency band and are separate from one another in the time domain.
• This kind of multiple access method is called a FDMA-TDD method (Frequency Division Multiple Access - Time Division Duplex).
• the essential parts of a structure of a typical radio system are described, by way of an example, in fig. 1.
• the system comprises a base station 100, and a number of usually mobile subscriber terminals 102-104 with a both-way connection 106, 108 and 110, 112 to the base station 100.
• data is transmitted 106 from the base station to e.g. terminal equipment 102 at the same frequency as from terminal equipment 102 to the base station 108, but the transmissions are not simultaneous.
• the terminal equipments 102-104 communicate with the other parts of the system and with the fixed network via the base station 100.
• An example of a system like this is the DECT system.
• traffic between a terminal equipment and a base station is transferred in frames.
• Fig. 2 shows an example of a DECT frame, which structurally is a frame typically used in the FDMA-TDD systems.
• the overall length of the frame is t F , which in connection with the DECT is 10 ms.
• the frame is divided into two parts 200, 202 of an equal size, where communication in different directions of transmission 106, 108 takes place.
• both halves of the frame 200, 202 comprise 12 time slots, each one of which is used in a normal situation for transmitting one signal.
• Time slots 1 and 13 carry information of one connection in both directions.
• the number of time slots assigned to the different directions of transmission can be changed dynamically according to the need.
• Fig. 3a shows an example of a solution according to the invention for dividing a frame between the different directions of transmission.
• the overall length of the frame is t F
• the number of time slots is n
• the frame is further divided into two parts 300, 302, which are used for transmitting traffic in the different directions of transmission 106, 108.
• the number of time slots assigned to the different directions of transmission is varied dynamically.
• the size of parts 300, 302 is thus adjusted according to the need.
• part 300 comprises k time slots 0...k-1
• part 302 comprises n-k time slots k...n-1.
• k n/2.
• the number of time slots can be varied with the capacity needed in the different directions of transmission.
• the base station monitors the capacity needed in the different directions of transmission and, if necessary, changes the number of time slots assigned to the different directions of transmission.
• the base station naturally has to signal the current division of the frame structure to the terminal equipments.
• the invention can also be applied in situations where more than one time slot is assigned to a connection between two transceivers. Since the different directions of transmission are assigned a different number of time slots, the number of time slots assigned for a connection in the different directions of transmission can be defined to be different according to the data transmission capacity needed.
• time slots 0...8 - i.e. 9 time slots - are assigned to one direction of transmission 304, and time slots 9...23 - i.e. 15 time slots - to the other direction of transmission 306.
• the radio system comprises at least one base station 100 and a number of terminal equipments 102-104. Data between the base station and the terminal equipments is transmitted in both directions 106, 108 on the same frequency band in frames comprising time slots. Time slots 300, 302 assigned to the different directions of transmission are separated from one another in the time domain. The number of time slots 300, 302 assigned to the different directions of transmission on each frequency band can be varied dynamically. In a preferred embodiment, the frame structure can be adjusted at the base station 100.

Landscapes

• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Mobile Radio Communication Systems (AREA)
• Time-Division Multiplex Systems (AREA)
• Transceivers (AREA)
• Bidirectional Digital Transmission (AREA)
• Radar Systems Or Details Thereof (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=8546616

Family Applications (1)

Country Status (7)

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Family Cites Families (7)

• 1996
  • 1996-09-06 FI FI963518A patent/FI963518A7/fi unknown
• 1997
  • 1997-09-05 AU AU42105/97A patent/AU723996B2/en not_active Ceased
  • 1997-09-05 EP EP97940174A patent/EP0923820A2/de not_active Withdrawn
  • 1997-09-05 CN CNB971977054A patent/CN1187916C/zh not_active Expired - Fee Related
  • 1997-09-05 WO PCT/FI1997/000524 patent/WO1998010540A2/en not_active Ceased
  • 1997-09-05 JP JP10512290A patent/JP2000517503A/ja not_active Ceased
• 1999
  • 1999-03-05 NO NO991095A patent/NO991095L/no not_active Application Discontinuation

Non-Patent Citations (1)

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