WO2015068039A2

WO2015068039A2 - Method and apparatus for transmitting and obtaining power headroom report

Info

Publication number: WO2015068039A2
Application number: PCT/IB2014/002727
Authority: WO
Inventors: Fanglei Sun; Tao Yang; Sigen Ye; Matthew Baker; Fang-Chen Cheng
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2013-11-05
Filing date: 2014-11-04
Publication date: 2015-05-14
Anticipated expiration: 2016-05-05
Also published as: WO2015068039A3; CN104619032A; CN104619032B

Abstract

Embodiments of the disclosure provide a method and apparatus for transmitting and obtaining a power headroom report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. The method for transmitting comprises: in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, determining a PHR for at least one of the first and second UL subframe sets; and transmitting to a base station an information block comprising the determined PHR, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set.

Description

METHOD AND APPARATUS FOR TRANSMITTING AND OBTAINING POWER HEADROOM REPORT

FIELD OF THE INVENTION

[0001] Embodiments of the present invention generally relate to communication techniques. More particularly, embodiments of the present invention relate to methods and apparatuses for transmitting and obtaining a power headroom report (PHR) in a Time Division Duplex (TDD) system.

BACKGROUND OF THE INVENTION

[0002] In a wireless communication system, power control is a significant technology. At present, the power control including an open-loop power control and a close-loop power control, is carried out at a user equipment (UE). Based on such power control, the user equipment needs to transmit a power headroom report to a base station, and the base station derives, based on the received power headroom report, a power spectral density (PSD) used by a physical uplink shared channel (PUSCH) at the user equipment and the remaining power headroom. Next, with the derived power spectral density and the remaining power headroom, the base station can determine how many resource units (RUs) can be allocated to the user equipment and a modulation and coding scheme (MCS) adapted to be used by the user equipment to guarantee obtaining an expected signal to interference plus noise ratio (SINR) on wireless links between the user equipment and the base station.

[0003] In a TDD system, there are seven different patterns of uplink (UL)/downlink (DL) switching, termed UL-DL configurations 0 through 6, which are schematically illustrated in Table 1. UL-DL Subframe Number

configuration 0 1 2 3 4 5 6 7 8 9

0 D S u u U D S U U U

1 D s u u D D S U U D

2 D s u D D D S u D D

3 D s u U U D D D D D

4 D s u U D D D D D D

5 D s u D D D D D D D

6 D s u U U D S U U D

Table 1

[0004] As illustrated in Table, a TDD radio frame consists of ten subframes indexed with 0 to 9. Each of the subframes may be used for DL transmission or UL transmission, or used as a special subframe between the DL period and the UL period. Taking configuration 0 for example, subframes 0 and 5 are used for the DL transmission, which are denoted as "D", subframes 2 to 4 and subframes 7 to 9 are used for the UL transmission, which are denoted as "U", and subframes 1 and 6 are used as special subframes, which are denoted as "S".

[0005] Further, depending on interference levels from neighboring base stations, all or part of UL subframes in a TDD radio frame can be divided into up to two UL subframe sets. Taking configuration 0 for example, the subframe 2 may be divided into one UL subframe set, and the subframes 3, 4, 7, 8 and 9 may be divided into the other UL subframe set.

[0006] For the PHR, due to the UL subframes in different UL subframe sets suffer different DL interference from neighboring base stations, the different open-loop operation point and close-loop power adjustment values for one step were agreed for different UL subframe sets, which results in that the PHR for different UL subframe sets should be different. However, in current specification, PHR is only considered for one UL subframe set. How to feedback to the base station the PHR for one/both UL subframe sets in a TDD system is still an open issue. SUMMARY OF THE INVENTION

[0007] Embodiments of the present invention propose solutions for transmitting and obtaining a PHR in a TDD system, so as to solve or at least partially mitigate at least a part of problems in the prior art.

[0008] According to a first aspect of embodiments of the present invention, there is provided a method for transmitting a power headroom report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. The method may comprise: in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, determining a PHR for at least one of the first and second UL subframe sets; and transmitting to a base station an information block comprising the determined PHR, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set.

[0009] In an exemplary embodiment, one of a first PHR for the first UL subframe set and a second PHR for the second UL subframe set may be determined in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets.

[0010] In an exemplary embodiment, a first PHR for the first UL subframe set and a second PHR for the second UL subframe set may be determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and the information block comprising both of the first and second PHRs may be transmitted.

[0011] In an exemplary embodiment, a first PHR for the first UL subframe set and a second PHR for the second UL subframe set may be determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and a first information block comprising the first PHR and a second information block comprising the second PHR may be transmitted, respectively.

[0012] In an exemplary embodiment, a first PHR for the first UL subframe set may be determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set is determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and a first information block comprising the first PHR and a second information block comprising the second PHR may be transmitted, respectively.

[0013] In an exemplary embodiment, a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set may be determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and the information block comprising both of the first and second PHRs may be transmitted.

[0014] In an exemplary embodiment, the one of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and wherein the information block comprising the one of the first and second PHRs is transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

[0015] In an exemplary embodiment, the one of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the information block comprising the one of the first and second PHRs may be transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets for which a PHR is determined.

[0016] In an exemplary embodiment, both of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and the information block comprising both of the first and second PHRs may be transmitted on a later scheduled UL subframe between a first scheduled UL subframe belonging to the first UL subframe set and a second scheduled UL subframe belonging to the second UL subframe set, the later scheduled UL subframe being immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied.

[0017] In an exemplary embodiment, one of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the other of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the information block comprising both of the first and second PHRs may be transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

[0018] In an exemplary embodiment, both of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the information block comprising both of the first and second PHRs may be transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets.

[0019] In an exemplary embodiment, both of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission; the first information block comprising the first PHR and the second information block comprising the first PHR are transmitted, respectively, on a respective scheduled UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

[0020] In an exemplary embodiment, the first PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the second PHR may be determined based on a hypothetical reference format corresponding to the second UL subframe set; the first information block comprising the first PHR may be transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to the first UL subframe sets; and the second information block comprising the second PHR may be transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to the second UL subframe set.

[0021] In an exemplary embodiment, both of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets, respectively; and the first information block comprising the first PHR and the second information block comprising the first PHR may be transmitted, respectively, on a respective UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

[0022] In an exemplary embodiment, the information block may be transmitted via a PHR control element.

[0023] In an exemplary embodiment, the PHR control element may comprise a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

[0024] In an exemplary embodiment, the PHR control element comprises: a first data portion comprising the first PHR; a first reserved field associated with first data portion and carrying an explicit subframe set indication for the first UL subframe set; a second reserved field associated with first data portion and carrying a power headroom value indication for the first UL subframe set, the power headroom value indication indicating whether the first PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the first UL subframe set; a second data portion comprising the second PHR; a second reserved field associated with second data portion and carrying an explicit subframe set indication for the second UL subframe set; and a second reserved field associated with second data portion and carrying a power headroom value indication for the second UL subframe set, the power headroom value indication indicating whether the second PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the second UL subframe set.

[0025] In an exemplary embodiment, the first data portion, the first and second reserved fields associated with the first data portion, and the second data portion, the first and second reserved fields associated with the second data portion, may be arranged in the PHR control element in a predetermined order.

[0026] In an exemplary embodiment, each of the first and second the information blocks may be transmitted via a PHR control element.

[0027] In an exemplary embodiment, the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

[0028] In an exemplary embodiment, the TDD system may be configured to support up to five component carriers; in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, a respective PHR for each of the component carriers is determined; and the information block comprising the PHR may be transmitted on a respective one of the component carriers.

[0029] In an exemplary embodiment, the information block may be transmitted via a PHR control element supporting the up to component carriers.

[0030] In an exemplary embodiment, the PHR control element may comprise a component carrier indication and the explicit subframe set indication associated with the component carrier indication.

[0031] In an exemplary embodiment, the implicit UL subframe set indication comprises an index of a UL subframe on which the information block may be transmitted.

[0032] According to a second aspect of embodiments of the present invention, there is provided a method for obtaining a PHR in a TDD system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. The method may comprise: receiving an information block from a user equipment, the information block comprising a PHR determined, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set; and analyzing the information block to obtain the PHR for at least one of the first and second UL subframe sets for the user equipment.

[0033] In an exemplary embodiment, one of a first PHR for the first UL subframe set and a second PHR for the second UL subframe set may be determined in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets.

[0034] In an exemplary embodiment, a first PHR for the first UL subframe set and a second PHR for the second UL subframe set may be determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and the information block comprising both of the first and second PHRs is received.

[0035] In an exemplary embodiment, a first PHR for the first UL subframe set and a second PHR for the second UL subframe set may be determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and a first information block comprising the first PHR and a second information block comprising the second PHR are received, respectively.

[0036] In an exemplary embodiment, a first PHR for the first UL subframe set may be determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set may be determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and a first information block comprising the first PHR and a second information block comprising the second PHR are received, respectively.

[0037] In an exemplary embodiment, a first PHR for the first UL subframe set may be determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set may be determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and the information block comprising both of the first and second PHRs is received.

[0038] In an exemplary embodiment, the one of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and the information block comprising the one of the first and second PHRs is received on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

[0039] In an exemplary embodiment, the one of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the information block comprising the one of the first and second PHRs is received on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets for which a PHR may be determined.

[0040] In an exemplary embodiment, both of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and the information block comprising both of the first and second PHRs may be transmitted on a later scheduled UL subframe between a first scheduled UL subframe belonging to the first UL subframe set and a second scheduled UL subframe belonging to the second UL subframe set, the later scheduled UL subframe being immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied.

[0041] In an exemplary embodiment, one of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the other of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the information block comprising both of the first and second PHRs is received on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

[0042] In an exemplary embodiment, both of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and wherein the information block comprising both of the first and second PHRs is received on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets.

[0043] In an exemplary embodiment, both of the first and second PHRs may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission; the first information block comprising the first PHR and the second information block comprising the first PHR are received, respectively, on a respective scheduled UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

[0044] In an exemplary embodiment, the first PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the second PHR may be determined based on a hypothetical reference format corresponding to the second UL subframe set; the first information block comprising the first PHR is received on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to the first UL subframe sets; and the second information block comprising the second PHR is received on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to the second UL subframe set.

[0045] In an exemplary embodiment, both of the first and second PHRs may be determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets, respectively; the first information block comprising the first PHR and the second information block comprising the first PHR are received, respectively, on a respective UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

[0046] In an exemplary embodiment, the information block may be transmitted via a PHR control element.

[0047] In an exemplary embodiment, the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

[0048] In an exemplary embodiment, the PHR control element comprises: a first data portion comprising the first PHR; a first reserved field associated with first data portion and carrying an explicit subframe set indication for the first UL subframe set; a second reserved field associated with first data portion and carrying a power headroom value indication for the first UL subframe set, the power headroom value indication indicating whether the first PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the first UL subframe set; a second data portion comprising the second PHR; a second reserved field associated with second data portion and carrying an explicit subframe set indication for the second UL subframe set; and a second reserved field associated with second data portion and carrying a power headroom value indication for the second UL subframe set, the power headroom value indication indicating whether the second PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the second UL subframe set;

[0049] In an exemplary embodiment, the first data portion, the first and second reserved fields associated with the first data portion, and the second data portion, the first and second reserved fields associated with the second data portion, are arranged in the PHR control element in a predetermined order.

[0050] In an exemplary embodiment, each of the first and second the information blocks are received via a PHR control element.

[0051] In an exemplary embodiment, the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR may be determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

[0052] In an exemplary embodiment, the TDD system is configured to support up to five component carriers; a respective PHR for each of the component carriers may be determined in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets; and the information block comprising the PHR is received on a respective one of the component carriers.

[0053] In an exemplary embodiment, the information block is received via a PHR control element supporting the up to five component carriers.

[0054] In an exemplary embodiment, the PHR control element comprises a component carrier indication and the explicit subframe set indication associated with the component carrier indication.

[0055] In an exemplary embodiment, the implicit UL subframe set indication comprises an index of a UL subframe on which the information block may be transmitted.

[0056] According to a third aspect of embodiments of the present invention, there is provided an apparatus for transmitting a power headroom report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. The apparatus may comprise: a determining unit configured to determine, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, a PHR for at least one of the first and second UL subframe sets; and a transmitting unit configured to transmit to a base station an information block comprising the determined PHR, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set.

[0057] In an exemplary embodiment, the determining unit may be configured to determine one of a first PHR for the first UL subframe set and a second PHR for the second UL subframe set in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets.

[0058] In an exemplary embodiment, the determining unit may be configured to determine a first PHR for the first UL subframe set and a second PHR for the second UL subframe set, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and the transmitting unit configured to transmit the information block comprising both of the first and second PHRs.

[0059] In an exemplary embodiment, the determining unit may be configured to determine a first PHR for the first UL subframe set and a second PHR for the second UL subframe set, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and the transmitting unit may be configured to transmit a first information block comprising the first PHR and a second information block comprising the second PHR, respectively.

[0060] In an exemplary embodiment, the determining unit may be configured to determine a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set is determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and the transmitting unit may be configured to transmit a first information block comprising the first PHR and a second information block comprising the second PHR, respectively.

[0061] In an exemplary embodiment, the determining unit may be configured to determine a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set in response to satisfying a second trigger condition predetermined for the second UL subframe set; and the transmitting unit may be configured to transmit the information block comprising both of the first and second PHRs.

[0062] In an exemplary embodiment, the determining unit may be configured to determine the one of the first and second PHRs is determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and the transmitting unit may be configured to transmit the information block comprising the one of the first and second PHRs on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

[0063] In an exemplary embodiment, the determining unit may be configured to determine the one of the first and second PHRs based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the transmitting unit may be configured to transmit the information block comprising the one of the first and second PHRs on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets for which a PHR is determined.

[0064] In an exemplary embodiment, the determining unit may be configured to determine both of the first and second PHRs based on a maximum transmission power and a pre-assigned power in a UL transmission; and the transmitting unit may be configured to transmit the information block comprising both of the first and second PHRs on a later scheduled UL subframe between a first scheduled UL subframe belonging to the first UL subframe set and a second scheduled UL subframe belonging to the second UL subframe set, the later scheduled UL subframe being immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied.

[0065] In an exemplary embodiment, the determining unit may be configured to determine one of the first and second PHRs based on a maximum transmission power and a pre-assigned power in a UL transmission, and the other of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the transmitting unit may be configured to transmit the information block comprising both of the first and second PHRs on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

[0066] In an exemplary embodiment, the determining unit may be configured to determine both of the first and second PHRs based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and the transmitting unit may be configured to transmit the information block comprising both of the first and second PHRs on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets.

[0067] In an exemplary embodiment, the determining unit may be configured to determine both of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and the transmitting unit may be configured to transmit the first information block comprising the first PHR and the second information block comprising the first PHR respectively, on a respective scheduled UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

[0068] In an exemplary embodiment, the determining unit may be configured to determine the first PHR based on a maximum transmission power and a pre-assigned power in a UL transmission, and to determine the second PHR based on a hypothetical reference format corresponding to the second UL subframe set; the first information block comprising the first PHR is transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to the first UL subframe sets; and the second information block comprising the second PHR is transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to the second UL subframe set.

[0069] In an exemplary embodiment, the determining unit may be configured to determine both of the first and second PHRs based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets, respectively; and the transmitting unit may be configured to transmit the first information block comprising the first PHR and the second information block comprising the first PHR, respectively, on a respective UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

[0070] In an exemplary embodiment, the information block may be transmitted via a PHR control element.

[0071] In an exemplary embodiment, the PHR control element may comprise a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

[0072] In an exemplary embodiment, the PHR control element may comprise: a first data portion comprising the first PHR; a first reserved field associated with first data portion and carrying an explicit subframe set indication for the first UL subframe set; a second reserved field associated with first data portion and carrying a power headroom value indication for the first UL subframe set, the power headroom value indication indicating whether the first PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the first UL subframe set; a second data portion comprising the second PHR; a second reserved field associated with second data portion and carrying an explicit subframe set indication for the second UL subframe set; and a second reserved field associated with second data portion and carrying a power headroom value indication for the second UL subframe set, the power headroom value indication indicating whether the second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the second UL subframe set.

[0073] In an exemplary embodiment, the first data portion, the first and second reserved fields associated with the first data portion, and the second data portion, the first and second reserved fields associated with the second data portion, are arranged in the PHR control element in a predetermined order.

[0074] In an exemplary embodiment, each of the first and second the information blocks are transmitted via a PHR control element.

[0075] In an exemplary embodiment, the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

[0076] In an exemplary embodiment, the TDD system is configured to support up to five component carriers; the determining unit may be configured to determine, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, a respective PHR for each of the component carriers; and the transmitting unit may be configured to transmit the information block comprising the PHR on a respective one of the component carriers.

[0077] In an exemplary embodiment, the information block may be transmitted via a PHR control element supporting the up to component carriers.

[0078] In an exemplary embodiment, the PHR control element may comprise a component carrier indication and the explicit subframe set indication associated with the component carrier indication.

[0079] In an exemplary embodiment, the implicit UL subframe set indication may comprise an index of a UL subframe on which the information block is transmitted. [0080] According to a fourth aspect of embodiments of the present invention, there is provided an apparatus for obtaining a PHR report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. The apparatus may comprise a receiving unit configured to receive an information block from a user equipment, the information block comprising a PHR determined, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set; and an analyzing unit configured to analyze the information block to obtain the PHR for at least one of the first and second UL subframe sets for the user equipment.

[0081] By employing the proposed solutions, the UE can transmit to the base station one or both of the power headrooms for the first and second UL suframe set.

[0082] Other features and advantages of the embodiments of the present invention will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Embodiments of the invention are presented in the sense of examples and their advantages are explained in greater detail below, with reference to the accompanying drawings, wherein:

[0084] Fig. 1 illustrates a flow chart of a method for transmitting a power headroom report (PHR) in a Time Division Duplex (TDD) system according to embodiments of the invention;

[0085] Fig. 2 schematically illustrates a MAC control element for PHR with a first format when a single component carrier is used in the TDD system;

[0086] Fig. 3 schematically illustrates a MAC control element supporting multiple component carriers;

[0087] Fig. 4 schematically illustrates a modified format of the MAC control element the MAC control element as shown in Fig. 3; [0088] Fig. 5 schematically illustrates a MAC control element for PHR with a second format when a single component carrier is used in the TDD system;

[0089] Fig. 6 illustrates a flow chart of a method for obtaining a power headroom report in a TDD system according to embodiments of the invention;

[0090] Fig. 7 illustrates a block diagram of an apparatus for transmitting a power headroom report in a TDD system according to embodiments of the invention; and

[0091] Fig. 8 illustrates a block diagram of an apparatus for obtaining a power headroom report in a TDD system according to embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0092] Embodiments of the invention will be described thoroughly hereinafter with reference to the accompanying drawings. It will be apparent to those skilled in the art that the invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and specific details set forth herein. Like numbers refer to like elements throughout the specification.

[0093] Embodiments of the present invention may be applied in various TDD systems, including but not limited to a LTE TDD system, a LTE-A TDD system, a LTE TDD elMTA (Enhanced Interference Management and Traffic Adaptation) system, a LTE-A TDD elMTA system. Given the rapid development in communications, there will of course also be future type wireless communication technologies and systems with which the present invention may be embodied. It should not be seen as limiting the scope of the invention to only the aforementioned system.

[0094] In a context of the present disclosure, a user equipment (UE) may refer to a terminal, a Mobile Terminal (MT), a Subscriber Station (SS), a Portable Subscriber Station (PSS), a Mobile Station (MS), or an Access Terminal (AT), and some or all of the functions of the UE, the terminal, the MT, the SS, the PSS, the MS, or the AT may be included.

[0095] Furthermore, in a context of the present disclosure, a base station (BS) may represent, e.g., a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a relay, a low power node such as a femto, a pico, and so on.

[0096] First, reference is made to Fig. 1, which illustrates a method 100 for transmitting a power headroom report (PHR) in a TDD system according to embodiments of the invention. In accordance with embodiments of the present invention, the method 100 may be carried out by, for example, a UE, a MT, a SS, a PSS, a MS, an AT or any other suitable device in the TDD system. In embodiments of the present invention, the TDD system is configured with a first uplink (UL) subframe set and a second UL subframe set. As discussed above, all or part of UL subframes in a TDD radio frame can be divided into up to two UL subframe sets, such that the subframes in one UL subframe set suffer a higher interference level than those in the other UL subframe set. Taking configuration 0 in Table 1 for example, the first UL subframe set may comprise the subframe 2 in the configuration 0, and the second UL subframe set may comprise the subframes 3, 4, 7, 8 and 9. As will be appreciated by those skilled in the art, other ways of dividing UL subframe sets may be applicable to the embodiments of the present invention.

[0097] In step S 101, in response to satisfying a predetermined trigger condition, there is determined a power headroom for at least one of the first and second UL subframe sets.

[0098] In the case where a single component carrier is used in the TDD system, the predetermined trigger condition may comprise, but not limited to the following:

a) a significant change in estimated path-loss since the last PHR (hereinafter, which is also referred to as a "pathloss change trigger condition");

b) more than a configured time elapse since the previous PHR controlled by a "PHR prohibit timer" (hereinafter, which is also referred to as a "timer trigger condition"); and

c) more than a configured number of TPC commands implemented by the UE (hereinafter, which is also referred to as a "TPC trigger condition").

[0099] As can be appreciated by those skilled in the art, in the case where multiple component carriers are used in the TDD system, the predetermined trigger conditions as defined in the current specification may be used.

[00100] In an embodiment, the power headroom may be determined as follows:

(0 = PcMAxA - {

+ A_{TP c}(i) + f_c(i) }

( (l01og₁₀ ( (')) + ,c ( j)+a_c (jy PL_c +A_TF-C (i)+/_c (i))/l0 #type2 ( = ¾V1AX,_C ( ~ ^101ogl0

(^F ' ) + g (<))/l0 (Equation 1) where

-PH_{type c} is the power headroom for the type 1 ;

-PH_tyPE2_XC is the power headroom for the type 2;

- PCMAX_{J C} is the maximum transmission power of a UE;

- MPUSCH._C (i) is the number of resource units allocated to the 1^th carrier component;

- PO_PUSCHM) ^and ot_c j) are open loop power control parameters;

- PL_C is the estimated path loss;

- Δχρ_,ο 0) is the offset with respect to the transport format;

-f_c(j) is the function of the close-loop power control command; -h{- ) is the PUCCH format related parameter;

- p pucc_H (F) is the parameter corresponding to the PUCCH format la; and

- g(i) is the function of the close-loop power control command on the 1^th carrier component.

[00101] In step S 102, a PHR comprising the determined power headroom is transmitted to a base station.

[00102] Hereinafter, reference will made to Embodiments 1 to 3 to describe the method for transmitting a power headroom report according to the present invention in detail.

Embodiment 1

[00103] In the Embodiment 1, one trigger condition is predetermined for both of the first and second UL subframe sets, one of a first power headroom for the first UL subframe set and a second power headroom for the second UL subframe set is determined in response to satisfying the one trigger condition, and one PHR comprising the first power headroom or the second power headroom is transmitted to the base station.

[00104] Typically, the determination and transmission of PHR are triggered on a certain UL or DL subframe, which will be hereinafter referred to as a "trigger subframe". In Embodiment 1, when the predetermined trigger condition is satisfied, one of the first and second UL subframe sets which has a UL subframe, immediately subsequent to the certain UL or DL subframe on which the trigger condition is satisfied, on which the base station schedules an UL transmission, will be triggered to determine a respective PHR and transmit the PHR to the base station on the UL subframe. Thus, the UL subframe on which the base station schedules an UL transmission will be hereinafter referred to as an "available UL subframe".

[00105] In the case where the trigger conditions, such as the pathloss change trigger condition and the timer trigger condition, as mentioned above, are employed, the same trigger condition may be predetermined for both of the first and second UL subframe sets. For example, the pathloss change trigger condition may be used for both of the first and second UL subframe sets. Specifically, for example, the threshold of pathloss change may be predetermined to be 3dB. When the predetermined threshold is reached, if either of the first and second subframe sets has an available UL subframe, a power headroom for which is determined. Thus, one PHR comprising the power headroom for one of the first and second UL subframe sets is transmitted to the base station on the available UL subframe with PUSCH transmission. With Embodiment 1, the existing PHR trigger scheme could be maximumly reused.

[00106] In the case where the trigger condition, such as TPC trigger condition as mentioned above, is employed, the number of TPC commands may be calculated for each of the first and second subframe set separately. For example, the threshold for number of TPC commands may be predetermined to be 10. When the threshold 10 is reached, the calculated number of TPC commands for the first UL subframe set may be 9 and the calculated number of TPC commands for the second UL subframe set may be 10. Thus, in response to satisfying the TPC trigger condition, the power headroom for the second UL subframe set is determined.

[00107] In the case where the TPC trigger condition is employed, as described above, when the TPC trigger condition is satisfied, if the available UL subframe belongs to the triggered UL subframe set (for example, the second UL subframe set), the power headroom for the triggered UL subframe set may be determined, according to the Equation 1 as presented above, as an accurate value of the power headroom for the triggered UL subframe set. On the other hand, if the available UL subframe does not belong to the triggered UL subframe set (for example, the second UL subframe set) but belongs to the untriggered UL subframe set (for example, the first UL subframe set), the power headroom for the triggered UL subframe set may be estimated based on a hypothetical reference format corresponding to the triggered UL subframe set, as an estimated value of the power headroom for the triggered UL subframe set. Then, the PHR comprising the estimated value will be transmitted to the base station on a UL subframe immediately subsequent to the trigger suframe (i.e., later nearest UL subframe) belonging to the untriggered UL subframe set. Thus, a short delay of transmitting PHR may be obtained.

[00108] Upon receiving the PHR, the base station should be capable of identifying the PHR is for which UL subframe set among the first and second UL subframe sets. Specifically, the base station can identify the PHR is for which UL subframe set by the implicit subframe set indication included in the information block. As mentioned above, each of the subframes in a TDD radio fame has a respective index, i.e., 0-9. The implicit UL subframe set indication may be an index of a UL subframe on which the information block is transmitted. Thus, the base station can identify the PHR is for which UL subframe set by the index of the UL subframe on which the information block comprising the PHR is transmitted.

[00109] However, since the UL retransmission round-trip time (RTT) is not 10ms for configuration 0 and 6 in the TDD system, for the initial PHR for one UL subframe set, its retransmission may happen on the other UL subframe set. Thus, it is unreliable to distinguish the PHR for which UL subframe set just from the index of the UL subframe. In the circumstances, the base station can identify the PHR is for which UL subframe set by the explicit subframe set indication included in the information block. Specifically, there is proposes to transmit the information block comprising the PHR via a media access control (MAC) control element (CE) for PHR according to an embodiment of present invention.

[00110] Fig. 2 schematically illustrates a MAC control element for PHR with a first format when a single component carrier (CC) is used in the TDD system. As shown in Fig. 2, the MAC control element for PHR for the single CC comprises 6 bits for carrying the power headroom value, and two reserved bits, as denoted by Ri and R₂ in Fig.2. Therefore, one of the two reserved bits Ri and R₂ may be used for carrying a subframe set indication indicating the determined power headroom is for the first or second UL subframe set. When the reserved bit R₂ is used for carrying the subframe set indication, it can be preset that, for example, value of 0 for R₂ indicates that the PHR is for the first UL subframe set while value of 1 indicates that the PHR is for the second UL subframe set.

[00111] In considering the cases where the PHR may be mased on the estimation of a hypothetical reference format of the triggered UL subframe set to shorten the report delay, the other reserved bit, for example, Ri can be used for carrying a power headroom value indication indicating whether the power headroom value is an accurate value or an estimated value. For example, it can be preset that value of 0 for Ri indicates that the power headroom value is an accurate value while value of 1 indicates that the power headroom value is an estimated value.

[00112] It is to be noted that since the base station has a knowledge that whether the UL subframe on which the PHR is transmitted is scheduled or not, the base station can identify the PHR is determined based on the real UL transmission or an estimated value without the power headroom value indication in the reserved bit, for example, Ri.

[00113] In the cases where the TDD system, especially, the TDD elMTA is configured to support multiple (up to five) component carriers, the UE will report multiple PHRs with one PHR value per active CC, and the following two situations will occur.

[00114] Situation 1

[00115] The elMTA will only occur for the primary cell (Pcell) and no elMTA for secondary cell (Scell). The UE only needs to indicate which UL subframe set is used for two PHR value calculation of Pcell. In this case, the PHR may be transmitted to the base station via a PHR control element supporting multiple component carriers, such as a MAC control element supporting multiple component carriers.

[00116] Fig. 3 schematically illustrates a MAC control element supporting multiple component carriers. In the MAC control element as shown in Fig. 3, each of CI, C2, C3...C7 indicate an index of respective component carriers; Pcmax, ci (i=l ...m) indicates a maximum transmission power on the 1^th component carrier; "P" indicates whether there is the value of Pcmax, ci; V indicates whether the transmitted power headroom value is an accurate value or an estimated value (for example, estimated based on a hypothetical reference format corresponding to a respective UL subframe set); PH (Type 1, Pcell) indicates the power headroom for Type 1 for Pcell; PH (Type 2, Pcell) indicates the power headroom for Type 2 for Pcell; PH (Type 1, Scell i (i=l ...n)) indicates the power headroom for Type 1 for Scell i; and R is a reserved field. Thus, the reserved bit R may used for carrying the subframe set indication. It can be preset that, for example, value of 0 for R indicates that the PHR is for the first UL subframe set while value of 1 indicates that the PHR is for the second UL subframe set.

[00117] It is to be noted that if the PHR is determined based on a hypothetical reference format of the corresponding UL suframe set. There is already one bit "V" in the MAC control element as shown in Fig. 3 to indicate whether the power headroom value is an accurate value or an estimated value for each component carrier.

[00118] Situation 2

[00119] The elMTA will be supported for both of the Pcell and Scell(s). UE should indicates the set information for PHR value calculations for both of the Pcell and Scells. When elMTA is enabled for all component carriers, different component carriers may have different TDD UL-DL configurations. Based on the UL interference suffered from the neighboring cells, the first and second UL subframe sets on different component carriers may be different from each other. Thus, a subframe set indication may be added to the MAC control element as shown in Fig. 3 so as to indicate the transmitted power headroom is for the first/or second UL subframe set for multiple component carriers, as shown in Fig. 4. In Fig. 4, the subframe set indication of one byte associated with the component carrier indication is added to the MAC control element. The bit location on this byte shares the same mapping as the component carrier indication in the above byte.

Embodiment 2

[00120] In the Embodiment 2, one trigger condition is predetermined for both of the first and second UL subframe sets, a first PHR for the first UL subframe set and a second PHR for the second UL subframe set are determined, respectively, in response to satisfying the one trigger condition.

[00121] In the Embodiment 2, the trigger conditions, such as pathloss change trigger condition, timer trigger condition and TPC trigger condition, may be employed, as described in the Embodiment 1. As described above, the first and second UL subframe sets share the same timer and passloss changes for both UL subframe sets, while the number for TPC commands may be calculated for both of the UL subframe sets. Once the trigger condition is satisfied, a first power headroom for the first UL subframe set and a second power headroom for the second UL subframe set are determined, respectively. For the transmission of the first and second power headrooms, there are two solutions as described below.

[00122] Solution 1

[00123] The first PHR comprising the first power headroom and the second PHR comprising the second power headroom are transmitted, respectively. When a single component carrier is used in the TDD system, each of the first PHR and the second PHR may be transmitted via the MAC control element for PHR as shown in Fig. 2.

[00124] With respect to the determination of the first and second power headrooms, when the trigger condition is satisfied, if there is a following available UL subframe which belongs to the first/second UL subframe set, the power headroom for the first/second UL subframe set may be determined, according to the Equation 1 as presented above, as an accurate value of the power headroom for the first/second UL subframe set. On the other hand, if there is not a following available UL subframe which belongs to the first/second UL subframe set, the power headroom for the first/second UL subframe set may be estimated based on a hypothetical reference format corresponding to the first/second UL subframe set, as an estimated value of the power headroom for the first/second UL subframe set. Then, the PHR comprising the estimated value for the first/second UL subframe set will be transmitted to the base station on a later nearest UL subframe belonging to the second/first UL subframe set.

[00125] The advantage of Solution 1 is that two PHR can be fed back to the base station timely. However, two MAC control elements will be sent, which may lead to some Layer 2 overhead.

[00126] Solution 2

[00127] There is transmitted a single PHR comprising both of the first power headroom for the first UL subframe set and the second power headroom for the second UL subframe set, so as to save Layer 2 overhead. There are three options to transmit the single PHR comprising both of the first and second power headrooms.

[00128] Option 1: both the first power headroom and the second power headroom are calculated based on available UL transmissions. That is, the first power headroom is determined with respect to an available UL subframe of the first UL subframe set, and the second power headroom is determined with respect to an available UL subframe of the second UL subframe set. Then, the single PHR comprising the accurate values of the first and second power headrooms are transmitted on a later UL subframe between the available UL subframe of the first UL subframe set and the available UL subframe of the second UL subframe set.

[00129] Option 2: one of the first power headroom and the second power headroom is determined based on an available UL transmission, and the other is estimated based on a hypothetical reference format corresponding to the respective UL subframe set. Then, the single PHR comprising an accurate value of the first/second power headroom and an estimated value of the second/first power headroom is transmitted to the base station on an available UL subframe of the first/second UL subframe set.

[00130] Option 3: the first power headroom and the second power headroom are estimated based on a hypothetical reference format corresponding to the respective UL subframe set, respectively. Then, the single PHR comprising the estimated values of the first and second power headrooms is transmitted on a later nearest UL subframe belonging to one of the first and second UL subframe sets.

[00131] When a single component carrier is used in the TDD system, the single

PHR may be transmitted via a MAC control element with a second format as shown in Fig. 5.

[00132] As shown in Fig. 5, the MAC control element with the second format comprises a first payload portion 501 and a second payload portion 502. The first payload portion 501 comprises 6 bits for carrying first power headroom for the first UL subframe set and a first reserved field L carrying an indication for the first UL subframe set. The second payload portion 502 comprises 6 bits for carrying the second power headroom for second first UL subframe set and a second reserved field I₂ carrying an indication for the second UL subframe set.

[00133] For example, it can be preset that value of 0 for L indicates that the

PHR is for the first UL subframe set while value of 1 indicates that the PHR is for the second UL subframe set. Similarly, it can be preset that value of 0 for I₂ indicates that the PHR is for the first UL subframe set while value of 1 indicates that the PHR is for the second UL subframe set.

[00134] In considering the cases where the PHR may be mased on the estimation of a hypothetical reference format of the triggered UL subframe set to shorten the report delay, the other reserved bit of the first payload portion 501 and second payload portion 502, Vi and V₂ can be used for carrying first and second power headroom value indications indicating whether the respective power headroom values are accurate values or estimated values. For example, it can be preset that value of 0 for Vi indicates that the first power headroom value is an accurate value while value of 1 indicates that the first power headroom value is an estimated value, and it can be preset that value of 0 for V₂ indicates that the second power headroom value is an accurate value while value of 1 indicates that the second power headroom value is an estimated value.

[00135] As an alternative, the first reserved field L and the second reserved field I₂ may not be used. Instead, the first power headroom value and the second power headroom value are inserted into the first and second payload portions 501, 502 in a predetermined order.

[00136] When multiple component carriers are used in the TDD system, the single PHR may be transmitted via the MAC control element as shown in Fig. 5 with the definition of the reserved bit "R" being modified. Specifically, the first power headroom and the second power headroom are inserted into the MAC control element as shown in Fig. 5 in a predetermined order, and different value of the reserved bit "R" indicates the predetermined order. For example, value of 0 for R indicates that the first power headroom is prior to the second power headroom while value of 1 indicates that the first power headroom is after the second power headroom.

[00137] It is to be noted that in this Embodiment, when a single trigger condition is maintained for both of the first and second UL subframe sets, two timers such as periodicPHR-Timer, prohibitPHR-Timer may be used and may be operated, respectively. When any of the two timers is expired, the PHRs for both of the first and second UL subframe sets are determined and transmitted to the base station in the first UL subframe of the corresponding set in which a new PUSCH transmission occurs after the trigger. Alternatively, one timer may be used to save a report load. Embodiment 3

[00138] In the Embodiment 3, a first trigger condition is predetermined for the first UL subframe set and a second trigger condition is predetermined for the second UL subframe set, respectively, and two independent PHR procedures for the two UL subframe sets. For each of the first and second UL subframe sets, the PHR procedure follows exactly what is defined in the current specification. This means that there will separate timer etc maintained for each UL subframe set. For the transmissions of the first and second power headrooms, there are two solutions as described below.

[00139] Solution 1

[00140] In Solution 1, one/both of the first and second power headrooms could be based on either the real UL transmission, or the estimation with a hypothetical reference format. A first PHR comprising the first power headroom and a second PHR comprising the second power headroom are transmitted, respectively. Both of the first and second PHRs may be transmitted with the MAC control element as shown in Fig. 2.

[00141] Solution 2

[00142] In Solution 2, the first PHR comprising the first power headroom and a second PHR comprising the second power headroom are transmitted simultaneously, as described in Solution 2 of Embodiment 2. Thus, the Layer 2 signaling may be saved and the report delay may be reduced.

According to a second aspect of embodiments of the present invention, there is provided a method for obtaining a PHR in a TDD system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. Reference is now made to Fig. 6, which illustrates a flowchart of method 600 for obtaining a power headroom report (PHR) in a TDD system according to embodiments of the present invention. The method 600 may be carried out in a base station, a NodeB, an eNodeB, a relay, a low power node and so on. As shown in Fig. 6, the method 600 comprises: in step S601, receiving an information block from a user equipment, the information block comprising a PHR determined, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set; and in step S602, analyzing the information block to obtain the PHR for at least one of the first and second UL subframe sets for the user equipment.

[00143] According to a third aspect of embodiments of the present invention, there is provided an apparatus for transmitting a PHR in a TDD system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. Reference is now made to Fig. 7, which illustrates a block diagram of the apparatus 700 for transmitting a PHR in a TDD system according to embodiments of the present invention. The apparatus 700 comprises a determining unit 701 configured to determine, in response to satisfying a predetermined trigger condition, a power headroom for at least one of the first and second UL subframe sets; and a transmitting unit 702 configured to transmit to a base station a PHR comprising the determined power headroom.

[00144] In accordance with embodiments of the present invention, the apparatus 700 may be implemented in a UE, a MT, a SS, a PSS, a MS, an AT or any other suitable device in a TDD system.

[00145] According to a fourth aspect of embodiments of the present invention, there is provided an apparatus for obtaining a PHR in a TDD system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set. Reference is now made to Fig. 8, which illustrates a block diagram of the apparatus 800 for obtaining a PHR in a TDD system according to embodiments of the present invention. The apparatus 800 comprises a receiving unit 801configured to receive a PHR from a user equipment, the PHR comprising a power headroom determined, in response to satisfying a predetermined trigger condition, for at least one of the first and second UL subframe sets; and an analyzing unit 802 configured to analyze the PHR to obtain the power headroom for at least one of the first and second UL subframe sets for the user equipment.

[00146] In accordance with embodiments of the present invention, the apparatus 800 may be implemented in a BS, a NodeB, a eNodeB, a central unit, a controller, a server or any other suitable device in a TDD system.

[00147] It will be understood that the words "comprising" or "comprise" do not exclude other elements or steps, that the words "a" or "an" do not exclude a plurality, and that a single element, such as a computer system, a processor, or another integrated unit may fulfill the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned. The terms "first", "second", third" and the like, when used in the description or in the claims are introduced to distinguish between similar elements or steps and are not necessarily describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the invention are capable of operating according to the present invention in other sequences, or in orientations different from the one(s) described or illustrated above.

[00148] Although the present invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied with various changes and modifications without departing from the scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. In other words, it is contemplated to cover any and all modifications, variations or equivalents that fall within the scope of the basic underlying principles and whose essential attributes are claimed in this patent application.

[0001] It will be appreciated that aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit or IC, in a plurality of units or ICs or as part of other functional units.

Claims

WHAT IS CLAIMED IS:

1. A method for transmitting a PHR report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set, the method comprising:

in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, determining a PHR for at least one of the first and second UL subframe sets; and

transmitting to a base station an information block comprising the determined PHR, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set.

2. The method according to Claim 1, wherein one of a first PHR for the first UL subframe set and a second PHR for the second UL subframe set is determined in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets.

3. The method according to Claim 1, wherein a first PHR for the first UL subframe set and a second PHR for the second UL subframe set are determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and

wherein the information block comprising both of the first and second PHRs is transmitted.

4. The method according to Claim 1, wherein a first PHR for the first UL subframe set and a second PHR for the second UL subframe set are determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and

wherein a first information block comprising the first PHR and a second information block comprising the second PHR are transmitted, respectively.

5. The method according to Claim 1, wherein a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set is determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and

6. The method according to Claim 1, wherein a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set is determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and

7. The method according to Claim 2, wherein the one of the first and second PHRs is determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and

wherein the information block comprising the one of the first and second PHRs is transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

8. The method according to Claim 2, wherein the one of the first and second PHRs is determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and

wherein the information block comprising the one of the first and second PHRs is transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets for which a PHR is determined.

9. The method according to Claim 3, wherein both of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and

wherein the information block comprising both of the first and second PHRs is transmitted on a later scheduled UL subframe between a first scheduled UL subframe belonging to the first UL subframe set and a second scheduled UL subframe belonging to the second UL subframe set, the later scheduled UL subframe being immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied.

10. The method according to Claim 3, wherein one of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the other of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and

wherein the information block comprising both of the first and second PHRs is transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

11. The method according to Claim 3, wherein both of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and

wherein the information block comprising both of the first and second PHRs is transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets.

12. The method according to Claim 4, wherein both of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission;

wherein the first information block comprising the first PHR and the second information block comprising the first PHR are transmitted, respectively, on a respective scheduled UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

13. The method according to Claim 4, wherein the first PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the second PHR is determined based on a hypothetical reference format corresponding to the second UL subframe set;

wherein the first information block comprising the first PHR is transmitted on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to the first UL subframe sets; and

wherein the second information block comprising the second PHR is transmitted on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to the second UL subframe set.

14. The method according to Claim 4, wherein both of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets, respectively;

wherein the first information block comprising the first PHR and the second information block comprising the first PHR are transmitted, respectively, on a respective UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

15. The method according to any of Claims 7-11, wherein the information block is transmitted via a PHR control element.

16. The method according to Claim 15, wherein the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

17. The method according to Claim 15, wherein the PHR control element comprises:

a first data portion comprising the first PHR;

a first reserved field associated with first data portion and carrying an explicit subframe set indication for the first UL subframe set;

a second reserved field associated with first data portion and carrying a power headroom value indication for the first UL subframe set, the power headroom value indication indicating whether the first PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the first UL subframe set;

a second data portion comprising the second PHR;

a second reserved field associated with second data portion and carrying an explicit subframe set indication for the second UL subframe set; and

a second reserved field associated with second data portion and carrying a power headroom value indication for the second UL subframe set, the power headroom value indication indicating whether the second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the second UL subframe set.

18. The method according to Claim 17, wherein the first data portion, the first and second reserved fields associated with the first data portion, and the second data portion, the first and second reserved fields associated with the second data portion, are arranged in the PHR control element in a predetermined order.

19. The method according to any of Claims 12-14, wherein each of the first and second the information blocks are transmitted via a PHR control element.

20. The method according to Claim 19, wherein the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

21. The method according to Claim 1, wherein the TDD system is configured to support up to five component carriers;

wherein in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, determining a respective PHR for each of the component carriers; and

wherein the information block comprising the PHR is transmitted on a respective one of the component carriers.

22. The method according to Claim 21, wherein the information block is transmitted via a PHR control element supporting the up to component carriers.

23. The method according to Claim 22, wherein the PHR control element comprises a component carrier indication and the explicit subframe set indication associated with the component carrier indication.

24. The method according to any Claims 1 to 23, wherein the implicit UL subframe set indication comprises an index of a UL subframe on which the information block is transmitted.

25. A method for obtaining a PHR report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set, the method comprising:

receiving an information block from a user equipment, the information block comprising a PHR determined, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set; and

analyzing the information block to obtain the PHR for at least one of the first and second UL subframe sets for the user equipment.

26. The method according to Claim 25, wherein one of a first PHR for the first UL subframe set and a second PHR for the second UL subframe set is determined in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets.

27. The method according to Claim 25, wherein a first PHR for the first UL subframe set and a second PHR for the second UL subframe set are determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and

wherein the information block comprising both of the first and second PHRs is received.

28. The method according to Claim 25, wherein a first PHR for the first UL subframe set and a second PHR for the second UL subframe set are determined, respectively, in response to satisfying one trigger condition predetermined for both of the first and second UL subframe sets; and

wherein a first information block comprising the first PHR and a second information block comprising the second PHR are received, respectively.

29. The method according to Claim 25, wherein a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set is determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and

30. The method according to Claim 25, wherein a first PHR for the first UL subframe set is determined in response to satisfying a first trigger condition predetermined for the first UL subframe set, and a second PHR for the second UL subframe set is determined in response to satisfying a second trigger condition predetermined for the second UL subframe set; and

31. The method according to Claim 26, wherein the one of the first and second PHRs is determined based on a maximum transmission power and a pre-as signed power in a UL transmission; and

wherein the information block comprising the one of the first and second PHRs is received on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

32. The method according to Claim 26, wherein the one of the first and second PHRs is determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and

wherein the information block comprising the one of the first and second PHRs is received on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets for which a PHR is determined.

33. The method according to Claim 27, wherein both of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission; and

34. The method according to Claim 27, wherein one of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the other of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and

wherein the information block comprising both of the first and second PHRs is received on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to one of the first and second UL subframe sets.

35. The method according to Claim 27, wherein both of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets; and

wherein the information block comprising both of the first and second PHRs is received on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to one of the first and second UL subframe sets.

36. The method according to Claim 28, wherein both of the first and second PHRs are determined based on a maximum transmission power and a pre-assigned power in a UL transmission;

wherein the first information block comprising the first PHR and the second information block comprising the first PHR are received, respectively, on a respective scheduled UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

37. The method according to Claim 28, wherein the first PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission, and the second PHR is determined based on a hypothetical reference format corresponding to the second UL subframe set;

wherein the first information block comprising the first PHR is received on a scheduled UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the scheduled UL subframe belonging to the first UL subframe sets; and

wherein the second information block comprising the second PHR is received on a UL subframe immediately subsequent to a UL or DL subframe on which the trigger condition is satisfied, the UL subframe belonging to the second UL subframe set.

38. The method according to Claim 28, wherein both of the first and second PHRs are determined based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets, respectively;

wherein the first information block comprising the first PHR and the second information block comprising the first PHR are received, respectively, on a respective UL subframe immediately subsequent to a respective UL or DL subframe on which the trigger condition is satisfied.

39. The method according to any of Claims 31-35, wherein the information block is transmitted via a PHR control element.

40. The method according to Claim 29, wherein the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

41. The method according to Claim 39, wherein the PHR control element comprises:

a first data portion comprising the first PHR;

a first reserved field associated with first data portion and carrying an explicit subframe set indication for the first UL subframe set; a second reserved field associated with first data portion and carrying a power headroom value indication for the first UL subframe set, the power headroom value indication indicating whether the first PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the first UL subframe set;

a second data portion comprising the second PHR;

a second reserved field associated with second data portion and carrying a power headroom value indication for the second UL subframe set, the power headroom value indication indicating whether the second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to the second UL subframe set;

42. The method according to Claim 41, wherein the first data portion, the first and second reserved fields associated with the first data portion, and the second data portion, the first and second reserved fields associated with the second data portion, are arranged in the PHR control element in a predetermined order.

43. The method according to any of Claims 36-38 wherein each of the first and second the information blocks are received via a PHR control element.

44. The method according to Claim 43, wherein the PHR control element comprises a payload portion comprising the first or second PHR and a first reserved field carrying the explicit subframe set indication and/or a second reserved field carrying a power headroom value indication, the power headroom value indication indicating whether the first or second PHR is determined based on a maximum transmission power and a pre-assigned power in a UL transmission or based on a hypothetical reference format corresponding to a respective one of the first and second UL subframe sets.

45. The method according to Claim 25, wherein the TDD system is configured to support up to five component carriers;

wherein a respective PHR for each of the component carriers is determined in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets; and

wherein the information block comprising the PHR is received on a respective one of the component carriers.

46. The method according to Claim 45, wherein the information block is received via a PHR control element supporting the up to five component carriers.

47. The method according to Claim 46, wherein the PHR control element comprises a component carrier indication and the explicit subframe set indication associated with the component carrier indication.

48. The method according to any Claims 25 to 47, wherein implicit UL subframe set indication comprises an index of a UL subframe on which the information block is transmitted.

49. An apparatus for transmitting a PHR report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set, the apparatus comprising:

a determining unit configured to determine, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, a PHR for at least one of the first and second UL subframe sets; and

a transmitting unit configured to transmit to a base station an information block comprising the determined PHR, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set.

50. An apparatus for obtaining a PHR report (PHR) in a Time Division Duplex (TDD) system, the TDD system being configured with a first uplink (UL) subframe set and a second UL subframe set, the apparatus comprising: a receiving unit configured to receive an information block from a user equipment, the information block comprising a PHR determined, in response to satisfying a trigger condition predetermined for both of the first and second UL subframe sets, for at least one of the first and second UL subframe sets, an implicit UL subframe set indication and/or an explicit UL subframe set indication indication indicating the determined PHR is for the first or second UL subframe set; and

an analyzing unit configured to analyze the information block to obtain the PHR for at least one of the first and second UL subframe sets for the user equipment.