TDD time slot splitting

• US 9,699,322 B2
• Filed: 06/30/2014
• Issued: 07/04/2017
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Astely, David, Parkvall, Stefan, Nystrom, Per Johan Anders
• Primary Examiner(s): Pham, Chi H
• Assistant Examiner(s): Huang, Weibin
• Application Number:
  US14/319,856
• Publication Number:
  US 20150003303A1
• Time in Patent Office: 1,100 Days
• Field of Search: 370229, 370235, 370341, 370252, 370254, 370255, 709238, 709241, 709242
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04M 9/025 Time division multiplex systems, e.g. loop systems
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/1263 Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows

Abstract

The invention discloses a method for a cellular communications system, in which traffic is sent in frames, each frame comprising a first number of subframes, with a second number of said subframes being available for at least either uplink or downlink traffic. At least one of said second number of subframes is made to comprise at least three parts, as follows:

• • One part which is utilized for uplink traffic,
  • One part which is utilized for downlink traffic,
  • One part which is utilized as a guard period,
    with said guard period part being scheduled between the uplink and the downlink parts. The duration of at least two of said three parts may be varied to fit the current system need.

Claims

1. A method for use in a cellular communications system, comprising:

sending the traffic in frames by a transceiver, wherein at least some of said frames including at least one downlink subframe which contains downlink traffic but no uplink traffic, at least one uplink subframe which contains uplink traffic, but no downlink traffic and at least one special subframe, said special subframe comprising the following three parts;

One part which is utilized for downlink traffic,

One part which is utilized as a guard period,

One part which is utilized for uplink traffic,

with said guard period part being scheduled between the downlink and the uplink parts, wherein a total sum of a duration of the downlink part, the guard period and the uplink part constitutes a total subframe length, and wherein the duration of at least two of said three parts may be varied.

2. The method of claim 1, applied to a TDD-system, Time Division Duplex, which uses an unpaired frequency spectrum, so that uplink and down link traffic in at least a first plurality of cells in the system occur during different subframes.

3. The method of claim 2, in which the uplink and the downlink traffic occur on the same frequency.

4. The method of claim 1, applied to a half duplex FDD-system, Frequency Division Duplex, so that uplink and downlink traffic for one and the same user in at least a first number of cells in the system occur during different subframes, and on different frequencies.

5. The method of claim 1, according to which the guard period is one of said at least two of three parts, and according to which method the guard period is varied in duration with respect to at least one of the following parameters:

Interference from or with other cells in the same system, or other cells in other adjoining or co-located systems,

The size of the cell, which determines the maximum propagation round trip time, RTT, in the cell,

The modulation scheme used for traffic in the cell.

6. The method of claim 5, according to which the guard period is varied with respect to the interference from or with other cells in the system so that the duration of the guard period is made at least equal to the propagation time of signals from at least one controlling node in another cell in the system.

7. The method of claim 1, according to which the system is one in which an OFDM modulation method, Orthogonal Frequency Division Modulation is used in at least one of the uplink and downlink directions, and in which at least one of the uplink traffic and downlink parts in said second number of subframes is given a duration which corresponds to an integer number of OFDM symbols in the modulation method.

8. The method of claim 1, according to which said subframe which is made to comprise at least three parts is interposed after a subframe used for downlink traffic and is followed by a subframe which is used for uplink traffic, with the downlink part being first in said subframe.

9. The method of claim 1, according to which said subframe which is made to comprise at least three parts is interposed after a subframe used for uplink traffic and is followed by a subframe which is used for downlink traffic, with the uplink part being first in said subframe.

10. The method of claim 1, applied to an LTE system, Long Term Evolution.

17. The transceiver of claim 10, in which the guard period is one of said at least two of three parts, and is configured for varying the guard period in duration with respect to at least one of the following parameters:

Interference from or with other cells in the same system, or other cells in other adjoining or co-located systems,

The size of the cell, which determines the maximum propagation round trip time, RTT, in the cell,

The modulation scheme used for traffic in the cell.

18. The transceiver of claim 17, adapted to vary the guard period with respect to the interference from or with other cells in the system, so that the duration of the guard period is adapted to be at least equal to the propagation time of signals from at least one controlling node in another cell in the system.

11. A transceiver comprising:

a transmitter and a receiver, said transmitter and said receiver being configured to send and receive traffic in radio frames, at least some of said radio frames including at least one downlink subframe which contains downlink traffic but no uplink traffic, at least one uplink subframe which contains uplink traffic, but no downlink traffic and at least one special subframe, said special subframe comprising the following three parts;

One part which is utilized for downlink traffic,

One part which is utilized as a guard period,

One part which is utilized for uplink traffic,

wherein said guard period part is scheduled between the downlink and the uplink parts, and wherein a total sum of a duration of the downlink part, the guard period and the uplink part constitutes a total subframe length, and wherein the duration of at least two of said three parts may be varied.

12. The transceiver of claim 11, further configured for receiving information from an external source in the system regarding the varying of said three parts.

13. The transceiver of claim 11, further configured for transmitting to users in a cell of the system information regarding the duration of said three parts.

14. The transceiver of claim 11, adapted to be used in a TDD-system, Time Division Duplex, which uses an unpaired spectrum, so that uplink and downlink traffic occur during different subframes.

15. The transceiver of claim 14, adapted to be used on the same frequency for both uplink and downlink traffic.

16. The transceiver claim 11, adapted to be used in a half duplex FDD-system, Frequency Division Duplex, so that uplink and downlink traffic for one and the same user occur during different subframes, and on different frequencies.

19. The transceiver of claim 11, being adapted for use in a system in which an OFDM modulation method, Orthogonal Frequency Division Modulation is used in at least one of the uplink and downlink directions, configured for giving at least one of the uplink traffic and downlink parts in said second number of subframes a duration which corresponds to an integer number of OFDM symbols in the modulation method.

20. The transceiver of claim 11, configured for interposing said subframe which is comprised of at least three parts after a subframe used for downlink traffic and before a subframe which is used for uplink traffic, with the downlink part being first in said subframe.