Methods and arrangements in a wireless communication system

• US 9,236,924 B2
• Filed: 03/30/2011
• Issued: 01/12/2016
• Est. Priority Date: 03/30/2011
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Liu, Jinhua, Kazmi, Muhammad, Miao, Qingyu
• Primary Examiner(s): Jaroenchonwanit, Bunjob
• Application Number:
  US14/007,967
• Publication Number:
  US 20140192727A1
• Time in Patent Office: 1,749 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0673 using feedback from receiving side
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/06 TPC algorithms
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 52/221 using past power control commands
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

Method and arrangement in a user equipment for adjusting signals transmitted in uplink to a network node based on a feedback value received from the network node. The method includes transmitting a signal, to be received by the network node. A feedback signal is received from the network node, providing feedback on the transmitted signal. A value of a time delay of the received feedback signal is obtained. Signals transmitted in the uplink are adjusted according to the received feedback signal to compensate for the obtained time delay value of the received feedback signal. Related methods and arrangements in a network node are presented.

Claims

1. A method in a user equipment for adjusting signals transmitted an uplink to a network node, based on a feedback value received from the network node, the method comprising:

transmitting a signal to the network node,

receiving a feedback signal from the network node that provides feedback in response to the signal that was transmitted,

obtaining a time delay value of the feedback signal that was received,

determining, when adjusting the signals transmitted in the uplink, if the received feedback signal is related to the uplink signal transmitted on a transmission antenna of at least two transmission antennas used for uplink transmission based on the time delay value, and

adjusting signals transmitted in the uplink based on the value of the time delay of the feedback signal to compensate for the time delay value of the feedback signal and by selecting one transmission antenna of the at least two transmission antennas to be used for uplink transmission, based on the feedback signal related to the transmission antenna used for uplink transmission.

2. The method according to claim 1, wherein the time delay value of the feedback signal comprises a difference between a time when the user equipment transmits the uplink signal and a time when the user equipment receives the feedback signal from the network node.

3. The method according to claim 1, wherein the obtaining the time delay value of the feedback signal comprises:

transmitting a signal in the uplink at a transmission power level associated with a feedback reference value,

receiving a feedback value from the network node that provides feedback on the transmitted uplink signal,

comparing the feedback reference value with the feedback value that was received from the network node, and

responsive to the feedback reference value corresponding to the feedback value, determining the time delay value of the feedback signal to be a difference in time between the transmitting the signal in the uplink and the feedback value that was received.

4. The method according to claim 1, wherein the obtaining a time delay value of the feedback signal occurs during an obtaining period, the method further comprising:

preventing transmission power adjustment at the user equipment due to any Transmit Power Control commands received from the network node during the obtaining period.

5. The method according to claim 1, wherein the obtaining of the value of the time delay of the received feedback signal comprises:

obtaining the value of the time delay in response to at least one of;

receiving a request from the network node;

receiving a handover event;

determining that a certain time interval has passed since a previous time delay value was obtained;

periodic triggering, wherein a period of the periodic triggering is predetermined or configured by the network node;

determining that the user equipment is set into Open Loop Transmit Diversity mode, wherein Open Loop Transmit Diversity mode comprises Open Loop Antenna Switching mode or Open Loop Beam Forming mode;

changing of signal processing delay for generation of Transmit Power Control commands in the network node;

determining that an active time of the user equipment in Open Loop Transmit Diversity mode is longer than a threshold time;

changing of a best uplink cell of the user equipment in Open Loop Transmit Diversity mode;

determining that user equipment speed is above a threshold over a time interval;

or

determining that a received signal quality in the uplink and/or in the downlink is worse than a threshold over a time interval.

6. The method according to claim 1, wherein the obtaining the time delay value of the feedback signal comprises:

receiving at least a component of the time delay value of the feedback signal from the network node.

7. The method according to claim 1, wherein the user equipment comprises at least two transmission antennas, wherein one transmission antenna of the at least two transmission antennas is alternately used for uplink transmission while the other transmission antenna of the at least two transmission antennas is not used for uplink transmission at the same time, and wherein the user equipment is configured for uplink transmit diversity by Open Loop Antenna Switching, the method further comprising:

adjusting signals transmitted in the uplink by selecting one transmission antenna of the at least two transmission antennas for the uplink transmission.

8. The method according to claim 1, wherein the adjusting signals transmitted in the uplink comprises:

adjusting the transmission power of the user equipment according to a Transmit Power Control command, received from the network node, with compensation made for the obtained time delay value of the feedback signal.

9. The method according to claim 1, wherein the user equipment comprises at least two transmission antennas, wherein uplink transmission is performed on the at least two transmission antennas, transmitting the same signal simultaneously by adjusting a phase difference between the signals transmitted by the at least two antennas, such that a beam of the transmitted signal is created in certain direction, and wherein the user equipment is configured for uplink transmit diversity by Open Loop Beam Forming, the method further comprising:

adjusting signals transmitted in the uplink by selecting beam direction or phase difference between the signals transmitted by the at least two transmission antennas.

10. The method according to claim 9, further comprising:

determining, when adjusting the signals transmitted in the uplink, if the received feedback signal is related to the uplink signal transmitted at the currently used phase difference between the signals transmitted by the at least two transmission antennas based on the time delay value, and

adjusting signals transmitted in the uplink by selecting beam direction, or phase difference, based on the feedback signal related to the currently used phase difference between the signals transmitted by the at least two transmission antennas.

11. The method according to claim 1, wherein obtaining the value of the time delay of the received feedback signal comprises:

transmitting a sequence of uplink signals over a control channel at different transmission power levels P=(p₁, p₂, . . . , p_N) associated with a Transmit Power Control reference sequence TPC_ref=(r₁, r₂, . . . , r_N),

receiving, from the network node, a sequence of Transmit Power Control commands TPC_set=(TPC₁, TPC₂, . . . , TPC_Q) such that Q>

N, triggered by the transmitted sequence of uplink signals,

calculating a correlation sequence C=(c₀, c₁, . . . , c_Q-N) between TPC_ref and TPC_set such that

12. The method according to claim 11, wherein the transmitting the sequence of uplink signals comprises:

transmitting a pre-determined sequence of uplink signals stored in a memory of the user equipment.

13. The method according to claim 11, wherein the transmitting the sequence of uplink signals comprises:

transmitting the sequence of uplink signals configured by the network node.

14. A user equipment for adjusting signals transmitted in an uplink to a network node, based on a feedback value received from the network node, the user equipment comprising:

a transmitter configured to transmit a signal to the network node,

a receiver, configured to receive a feedback signal from the network node, providing feedback in response to the signal that was transmitted,

a processing circuit, configured to obtain a time delay value of the feedback signal that was received, determine if the received feedback signal is related to the signal transmitted on a transmission antenna of at least two transmission antennas used for uplink transmission based on the time delay value, adjust signals transmitted in the uplink based on the value of the time delay of the feedback signal, wherein compensation is made for the obtained time delay value of the feedback signal, and select one transmission antenna of the at least two transmission antennas to be used for uplink transmission, based on the feedback signal related to the transmission antenna used for uplink transmission.

15. The user equipment according to claim 14, further comprising:

a memory configured to store a pre-determined sequence of uplink signals to be transmitted at different transmission power levels associated with a reference sequence.

16. The user equipment according to claim 14, further comprising:

a first transmission antenna, and a second transmission antenna, wherein the first and the second transmission antennas are configured to operate in Open Loop Transmit Diversity mode, wherein Open Loop Transmit Diversity mode comprises Open Loop Antenna Switching mode or Open Loop Beam Forming mode.

17. A network node for providing a value of a time delay of a feedback signal transmitted to a user equipment for adjustment of signals transmitted in the uplink by the user equipment, based on a feedback value provided by the network node, the network node comprising:

a processing circuit, configured to determine that the user equipment is to adjust signals transmitted in the uplink, based on the value of the time delay of the feedback signal, and

a transmitter, configured to transmit a request to be received by the user equipment, triggering the user equipment to determine the time delay value of the feedback signal and to transmit a Transmit Power Control command, based on the time delay value of the feedback signal, to the user equipment for adjusting the transmission power of the user equipment.

18. A method in a network node for providing a value of a time delay of a feedback signal transmitted to a user equipment for adjustment of signals transmitted in the uplink by the user equipment, based on a feedback value provided by the network node, the method comprises:

determining that the user equipment is to adjust signals transmitted in the uplink, based on the value of the time delay of the feedback signal, and

transmitting a request to be received by the user equipment, triggering the user equipment to determine the time delay value of the feedback signal and to transmit a Transmit Power Control command, based on the time delay value of the feedback signal, to the user equipment for adjusting the transmission power of the user equipment.

19. The method according to claim 18, further comprising:

measuring at least a component of the time delay value of the feedback signal transmitted to the user equipment, and

providing the at least the component of the delay value that was measured to the user equipment.