Methods and apparatus for downlink PDSCH power setting

• US 8,238,455 B2
• Filed: 12/05/2008
• Issued: 08/07/2012
• Est. Priority Date: 01/07/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Zhang, Jianzhong, Pi, Zhouyue, Khan, Farooq, Tsai, Jiannan
• Primary Examiner(s): LEE, SIU M
• Application Number:
  US12/314,239
• Publication Number:
  US 20090175371A1
• Time in Patent Office: 1,341 Days
• Field of Search: 375/260, 375/316, 375/295, 375/345, 375/349, 375/267, 375/299
• US Class Current: 375/260
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

Methods and apparatus for transmitting power setting information in a downlink Physical Downlink Shared Channel (PDSCH) in a communication system. In this communication system, a plurality of methods for calculating traffic-to-pilot ratios (T2P) are established. In addition, a mapping scheme between a plurality of overhead signals and a plurality of reference signal (RS) overhead ratios, η_RS, and the plurality of T2P calculation methods is established. A user-specific T2P ratio P_B,k/P_RS for certain OFDM symbols, a RS overhead ratio η_RS and a calculation method selected from the plurality of T2P calculation methods are assigned to a wireless terminal. Then, an overhead signal corresponding to both of the assigned RS overhead ratio η_RS and the assigned T2P calculation method is selected in accordance with the mapping scheme and is transmitted to the wireless terminal. In addition, the user-specific traffic-to-pilot ratio P_B,k/P_RS is transmitted to the wireless terminal. The wireless terminal may calculate the traffic-to-pilot ratios across different transmission antennas and different OFDM symbols in dependence upon the received traffic-to-pilot ratio P_B,k/P_RS, and the RS overhead ratio and the T2P calculation method indicated by the RS overhead signal.

Claims

1. A method for calculating traffic-to-pilot ratios at a wireless terminal, the method comprising:

establishing a table for calculating traffic-to-pilot ratios at the wireless terminal in a communication system, with the wireless terminal having a plurality of OFDM symbols available for transmission, a subset of the OFDM symbols being used for transmitting reference signals;

receiving a reference signal (RS) overhead ratio η

_RS and a traffic-to-pilot ratio P_B,k/P_RS for certain Orthogonal Frequency Division Multiplexing (OFDM) symbols at the wireless terminal, with P_B,k being an Energy Per Resource Element (EPRE) power assigned on non-RS OFDM symbols, and P_RS being a RS power per subcarrier; and

calculating traffic-to-pilot ratios across different transmission antennas and different OFDM symbols in dependence upon the calculation table and a number of available transmission antennas in the wireless terminal.

2. The method of claim 1, wherein, when the number of available transmission antennas in the wireless terminal is one, the calculation table is established by:

3. The method of claim 1, wherein, when the number of available transmission antennas in the wireless terminal is two, the calculation table is established by:

4. The method of claim 1, wherein, when the number of available transmission antennas in the wireless terminal is four, the calculation table is established by:

5. The method of claim 1, wherein, when the number of available transmission antennas in the wireless terminal is four, the calculation table is established by:

6. The method of claim 1, wherein, when the number of available transmission antennas in the wireless terminal is four, the calculation table is established by:

7. A method for transmitting power setting information to a wireless terminal, the method comprising:

establishing a plurality of methods for calculating traffic-to-pilot ratios (T2P);

establishing a mapping scheme between a plurality of overhead signals, R_ovhd, and a plurality of reference signal (RS) overhead ratios, η

_RS, and the plurality of T2P calculation methods;

assigning a user-specific traffic-to-pilot ratio P_B,k/P_RS for certain Orthogonal Frequency Division Multiplexing (OFDM) symbols to the wireless terminal, with the wireless terminal having a plurality of OFDM symbols available for data transmission, a subset of the OFDM symbols being used for transmitting reference signals, with P_B,k being an Energy Per Resource Element (EPRE) power assigned on non-RS OFDM symbols, and P_RS being a RS power per subcarrier;

assigning a RS overhead ratio η

_RS and a calculation method selected from the plurality of T2P calculation methods to the wireless terminal; and

transmitting the user-specific traffic-to-pilot ratio P_B,k/P_RS, and the overhead signal, R_ovhd, corresponding to both of the assigned RS overhead ratio η

_RS and the assigned T2P calculation method in accordance with the mapping scheme, to the wireless terminal.

8. The method of claim 7, wherein the mapping scheme is established by:

9. The method of claim 8, wherein, when number of transmission antennas in the wireless terminal is one, the T2P calculation method is established by:

10. The method of claim 8, wherein, when number of transmission antennas in the wireless terminal is two, the T2P calculation method is established by:

11. The method of claim 8, wherein, when number of transmission antennas in the wireless terminal is four, the T2P calculation method is established by:

12. The method of claim 7, wherein, when number of transmission antennas in the wireless terminal is four, the mapping scheme is established by:

13. The method of claim 7, further comprising transmitting the RS overhead signal R_ovhd in one of a cell-specific broadcast message and a user-specific radio resource control (RRC) message.

14. The method of claim 13, wherein the cell-specific broadcast message comprises one of a Primary Broadcast Channel (BCH) message and a Dynamic BCH message.

15. The method of claim 7, further comprising transmitting a certain traffic-to-pilot ratio P_B,k/P_RS semi-statically in a radio resource control (RRC) message.

16. The method of claim 7, further comprising transmitting a certain traffic-to-pilot ratio P_B,k/P_RS dynamically in a Physical Downlink Control Channel (PDCCH) message.

17. A method for calculating traffic-to-pilot ratios, the method comprising:

receiving a reference signal (RS) overhead signal indicating both of a RS overhead ratio and a method for calculating traffic-to-pilot (T2P) ratios at a wireless terminal in a communication system;

receiving a certain traffic-to-pilot ratio P_B,k/P_RS, with the wireless terminal having a plurality of OFDM symbols available for data transmission, a subset of the OFDM symbols being used for transmitting reference signals, with P_B,k being an Energy Per Resource Element (EPRE) power assigned on non-RS OFDM symbols, and P_RS being a RS power per subcarrier; and

calculating the traffic-to-pilot ratios across different transmission antennas and different OFDM symbols in dependence upon the received traffic-to-pilot ratio P_B,k/P_RS, and the RS overhead ratio and the T2P calculation method indicated by the RS overhead signal.

18. A method for transmitting a power setting information to a wireless terminal, the method comprising:

assigning a plurality of traffic-to-pilot ratios P_A,k/P_RS and P_B,k/P_RS for different Orthogonal Frequency Division Multiplexing (OFDM) symbols and different transmission antennas to the wireless terminal, with the wireless terminal having a plurality of OFDM symbols available for data transmission, a subset of the OFDM symbols being used for transmitting reference signals (RS), P_A,k being an Energy Per Resource Element (EPRE) power assigned on RS OFDM symbols, P_R,k being an EPRE power assigned on non-RS OFDM symbols, and P_RS being a RS power per subcarrier; and

transmitting the assigned traffic-to-pilot ratios P_A,k/P_RS and P_B,k/P_RS explicitly to the wireless terminal.

19. A wireless terminal in a communication system, comprising:

a memory unit configured to store a plurality of methods for calculating traffic-to-pilot ratios (T2P), and to store a mapping scheme between a plurality of overhead signals, and a plurality of reference signal (RS) overhead ratios and the plurality of T2P calculation methods;

a power setting unit configured to assign a user-specific traffic-to-pilot ratio P_B,k/P_RS, a RS overhead ratio, η

_RS, and a calculation method selected from the plurality of T2P calculation methods to a second wireless terminal, with the second wireless terminal having a plurality of OFDM symbols available for data transmission, a subset of the OFDM symbols being used for transmitting reference signals, P_B,k being an Energy Per Resource Element (EPRE) power assigned on non-RS OFDM symbols, and P_RS being a RS power per subcarrier; and

at least one antenna configured to transmit an overhead signal corresponding to both of the assigned RS overhead ratio η

_RS and the assigned T2P calculation method in accordance with the mapping scheme, and the user-specific traffic-to-pilot ratio P_B,k/P_RS, to the second wireless terminal.

20. A wireless terminal in a communication system, comprising:

a memory unit configured to store a plurality of methods for calculating traffic-to-pilot ratios (T2P), and to store a mapping scheme between a plurality of overhead signals, and a plurality of reference signal (RS) overhead ratios and the plurality of T2P calculation methods;

at least one antenna configured to receive an overhead signal and a certain traffic-to-pilot ratio P_B,k/P_RS, with the wireless terminal having a plurality of OFDM symbols available for data transmission, a subset of the OFDM symbols being used for transmitting reference signals, P_B,k being an Energy Per Resource Element (EPRE) power assigned on non-RS OFDM symbols, and P_RS being a RS power per subcarrier; and

a power setting unit configured to calculate the traffic-to-pilot ratios across different transmission antennas and different OFDM symbols in dependence upon the received traffic-to-pilot ratio P_B,k/P_RS, and the RS overhead ratio and the T2P calculation method corresponding to the RS overhead signal.

21. A method for determining a transmit power from a base station at a wireless terminal, the base station having a plurality of OFDM symbols available for transmission, and a subset of the OFDM symbols being used for transmitting reference signals, with the method comprising:

receiving a semi-static parameter from a broadcast channel, with the semi-static parameter being denoted by P_B;

determining equal Energy Per Resource Element (EPRE) ratios among a first set of resource elements in the OFDM symbols not transmitting the reference signals, with a ratio of traffic data EPRE to pilot EPRE (T2P) among the first set of resource elements being denoted by ρ

_A; and

determining equal EPRE ratios among a second set of resource elements in the OFDM symbols transmitting the reference signals, with a ratio of traffic data EPRE to pilot EPRE (T2P) among the second set of resource elements being denoted by ρ

_B, with the ratio of ρ

_B to ρ

_A being determined in dependence upon one of a semi-static parameter P_B, and a semi-static pilot power overhead parameter, η

_RS, based on the following table;