AU2015202082B2 - Power control methods and apparatus - Google Patents

Abstract

Methods and apparatus for power control are described. Methods are included for calculating and signaling power control related data to support multiple component carriers (CCs) for which transmission may be accomplished with one or more WTRU power amplifiers (PAs). Methods are included for calculating and signaling one or more of CC-specific power control related data and PA-specific power control related data. The power control related data may include one or more of maximum power, power headroom, and transmit power. Methods for selecting which power control related data to exchange are included. Methods are included for calculating and signaling power control related data for physical UL shared channel (PUSCH), physical UL control channel (PUCCH), and simultaneous PUSCH and PUCCH transmission. -------------- Ntt EEv- 1: D.,

Description

POWER CONTROL M ETHODS AND APPARATUS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional application Nos. 61/247,676 filed on October 1, 2009; 61/248,373 filed on October 2, 2009; 61/285,343 filed on December 10, 2009; 81/329,194 filed on April 29, 2010; and 61/356,472 filed on June 18, 2010, the contents of which are hereby incorporated by reference herein.

FIELD OF THE INVENTION

[0002] This application is related to wireless communications.

BACKGROUND

[0003] Transmit power of a wireless transmit/receive unit (WTRU) may be determined in the WTRU based on measurements made by the WTRU and data received from an evolved NodeB (eNodeB). The WTRU transmit power control may be used for maintaining quality of service (QoS), controlling intercell interference, maximizing a WTRLPs battery life and the like.

[0004] In Third Generation Partnership Project (3GPP) long term evolution (LTE), uplink (UL) power control may be used to compensate for long-term fading, (including path loss and shadowing), while reducing inter-cell interference, and avoiding occurrences of the WTRU having to invoke its maximum power procedure to prevent its power amplifier (PA) from operating beyond its linear region and/or to prevent the 'WTRU from exceeding maximum transmit power limits imposed by the network, regulatory requirements, and the like. LTE power control methods may include combined open loop and closed loop power control methods. In LTE Release 8 (R8) and 9 (R9), the WTRU transmits on a single carrier over one antenna which maybe accomplished with one power amplifier (PA), Open and closed loop power control related data are exchanged between the eNodeB and the WTRU for the single transmit path. (.000.¾] In LIE R.8 and R9S power headroom may he used .for assisting the eNodeB to schedule the UL transmission resources of different WTRUs, In LT.E, power headroom, reported from the WTRU to the eNodeB, is the difference between the nominal WTRU maximum transmit power and the estimated power for PUSCH transmission for the single carrier. Maximum transmit power imposed by the network for the single carrier is signaled by the eNodeB to the WTRU in. system information. Additional limits.such as the WTRU's power class, its PA capabilities, and the like, may reduce the maximum transmit power used by the WTRU for the headroom calculation.

[0006] LTB R8 and R9 methods for calculating and signaling power headroom and other power control related data may not he sufficient to support multiple component carriers (CCs) which may require multiple WTRU PAs.

SUMMARY

[00()/] Methods and apparatus for power control are described. Methods are included for calculating and signaling power control related data to support multiple component carriers (CCs) for which transmission may be accomplished with one or more WTRU power amplifiers (PAs).

[0008] Methods are included for calculating and. signaling one or more of CC-specifie power control related data and. PA-sped fie power control related data. The power control related data may include one or more of maximum power, power headroom, and transmit power. Methods for selecting which power control related data to exchange are included. Methods are included for calculating and signaling power control related data for physical UL shared channel (PUSCH), physical UL control channel (PUCCH), and simultaneous PUSCH and PUCCH transmission.

[0008a] According to a first aspect of the present invention, there is· provided a wireless transmif/recei-ve unit (WTRU), the WTRU camprising: a processor configured to: calculate a physical uplink control channel. (PUCCH) transmit power associated with a reference downlink control information (DC1.) format in the absence of a PUCCH transmission; determine a power headroom using a physical uplink shared channel (PUSCH) transmit power and the PUCCH transmit power; and send the power headroom.

[0008b] According to another aspect of the invention, there is provided a method for reporting power headroom, the method comprising; calculating, by a wireless transmit/receive unit (WTRU), a physical uplink control channel (PUCCH) transmit power associated with a reference downlink control information (DO.) format m the absence of a PUCCH transmission; determining a power headroom using a physical uplink shared channel (PUSCH) transmit power and the PUCCH transmit power; and sending the power headroom.

[0008c] Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A. more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: [0010] FIG. 1A is a system diagram of an example communications system in which one or more disclosed embodiments may be implemented; [0011] FIG, IB is a system diagram of an example wireless transrait/receive unit (WTETJ) that may he used within the communications system illustrated in FIG. 1A; [0012] FIG. 1C is a system diagram of an example radio access network and an example core network that may he used within the communications system illustrated in FIG. 1A; [0018] FIGs, 2-4 are example flowcharts of a method of signaling of CC- specific headroom; and [0014] FIG. δ is an example diagram illustrating a power headroom reporting method.

DETAILS D DESCRIPTION

[0015] FIG, 1A is a diagram of an example com munications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may he a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc,, to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth . For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

[0016] As shown in FIG, 1A, the communications system .1.00 may include wireless transm.it/receive units {WTEUs) 1.02a, 102b, 102c, l.Q2d, a radio access network (RAN) 104, a core network 106. a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will he appreciated that the disclosed embodiments contemplate any number of WTEUs, base stations, networks, and/or network elements. Each of the WTEUs 102a, 102b, 102e, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include user equipment (UE), a mobile station, a feed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, consumer electronics, and the like.

[0017] The communications systems 100 may also include a base station 114a and a base station 114b. Bach of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106, the Internet 110, and/or the networks 112, By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0018] The base station 1,11a may be part of the RAN 104, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic region, which may be referred to as a cell (not shown). The cell may further fee divided into cell sectors. For example, the ceil associated with the base station 11.4a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, he,, one for each sector of the cell. In another embodiment, the base station 114a may employ multiple-input multiple output (ΜΙΜΟ) technology and, therefore, may utilize multiple transceivers for each sector of the cell.

[0019] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link Ce.g,, radio frequency (liF), microwave, infrared (JIt), ultraviolet (UV), visible light, etc.). The air interlace 116 may be established using any suitable radio access technology (RAT).

[0020] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TI)MA, FDMA. OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102 a, 102b, 102c may implement a radio technology' such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA*)· HSPA may include High-Speed Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

[0021] In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

[0022] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802,16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-20Q0), Interim Standard 95 (1S-95), Interim Standard 856 (IB-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0028] The base station 114b in FIG. 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such, as IEEE 802.11 to establish, a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 1.02c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA200G, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the core network 1.06, [0024] The RAN 104 may be in communication with the core network 106, which may he any type of network configured to provide voice, data, applications, and/or voice over internet· protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 and/or the core network 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may be utilizing an E-UTRA radio technology, the core network 106 may also be in communication with another RAN (not shown) employing a GSM radio technology.

[0025] The core network 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102-d to access the PSTN 108, the Internet 110, and/or other networks 112. The PSTN 108 may include circuit'switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that u se common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired or wireless communications networks owned and/or operated hv other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may employ the sa me RAT as the SAN 104 or a different ΚΑΊ1.

[0026] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b. 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102e shown in FIG, 1A may be configured to communicate with the base station ,1.14a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0027] FIG. IB is a system diagram of an example WTRU 102. As shown in FIG. IB, the WTRU 102 may include a processor 118, a transceiver 120. a transmit/reeeive element 122, a speaker/microphone 124, a keypad 126, a display/touehpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It will be appreciated that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0028] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller. Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, inpufc/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may he coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 maybe integrated together in an electronic package or chip.

[0029] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from , a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IE, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and recei ve both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0030] In addition, although the transmit/receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 may include any number of transmit/receive elements 122, More specifically, the WTRU 102 .may employ ΜΙΜΟ technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0031] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122, As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802,11, for example.

[0032] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/raicrophone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid cry stal display (LCD) display unit or organic light-emitting diode (OLED) display uni t). The processor 118 may also output user data to the speaker/raicrophone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0033] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 .maybe any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel ceils, and the like.

[0034] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g,, longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations, it will be appreciated that the WTRU 102 may acquire location i nformation by way of any suitable location-determination method while remaining consistent with an embodiment, [0035] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

[0036] FIG. 1C is a system diagram of the RAN 1.04 and the core network 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. The RAN 104 may also he in communication with the core network 106.

[0037] The RAN 104 may include eNode-Bs .1.40a, 140b, 140c, though it will he appreciated that the RAN 104 may include any number of eNcde-Bs while remaining consistent with an embodiment. The eNode-Bs 140a, 140b, 140c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 140a, 140b, 140e may implement ΜΙΜΟ technology. Thus, the eNode-B 140a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0038] Each of the eNode-Bs 140a, 140b, 140c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and/or downlink, and the like. As shown in FIG. 10, the eNode-Bs :1.40a, 140b, 140c may communicate with one another over an X2 interface, [0039] The core network 106 shown in FIG. 1C may include a mobility management gateway (MME) 142, a serving gateway 144, and a packet data network (PDN) gateway 146, While each of the foregoing elements are depicted as part of the core network 106, it will he appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

[0040] The MME 142 may be connected to each of the eNode-Bs 142a, 142b, 142c in the RAN 104 via an Si interface and may serve as a control node. For example, the MME 142 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 142 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[004Ij The serving gateway 144 may be connected, to each of the eNode Bs 140a, 140b, 140c in the RAN 104 via the Si interface. The serving gateway 144 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 144 may also perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0042] The serving gateway 144 may also be connected to the PBN gateway 146, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the internet 110. to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0048] The core network 106 may facilitate communications with other networks. For example, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the core network 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the core network 106 and the PSTN 108, In addition, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

[0044] in LTE Release 8 (R8), a WTRU reports (Le., signals or transmits) power headroom (PH) for one carrier to the base station. When conditions warrant the WTRU sending a PH report (PHR), the WTRU waits until a transmission interval (TTB for which the WTRU receives a valid uplink (UL) physical uplink shared channel (PUSCH) grant, i.e., UL resources, and then sends the PHR in that TTI.

[0045] In LTE-A, a WTRU may report po wer headroom for one, two or more component carriers (CCs) to the eNodeB. When conditions warrant the WTRU may send a PIER for at least one UL CC, PHRs for all active UL CCs, or PHRs for all configured UL CCs, for example if there is no explicit activation mechanism, and even if there is no UL grant for the specific TTI for a given UL CC. For the UL CCs which do not have a PUSCH grant, the WTRU may use a reference format or grant (Le., a set of grant parameters known to both the WTRU and the base station) to derive the PH for that UL CC.

[0046] Consequently, the WTEU may report PH for some combination of UL CCs with actual PUSCH grants and reference PUSCH grants. UL CCs with actual grants in a given TTI are referred to herein as real CCs or transmitted CCs. UL CCs that do not have actual gra nts, and may use reference grants, for the PH calculation are referred to herein as fake or virtual CCs, [0047] The base station may use the PHRs from WTRUs in deciding how to schedule UL resources in the future for these WTRUs. Due to the possibility of transmission on multiple CCs which may be implemented in the WTRU with one or more PAs, the base station may not have enough information to make appropriate scheduling decisions using the existing PH calculations and reports, [0048] In another aspect of LTE-A. a WTRU supporting UL transmission over multiple antenna ports may operate in multi-antenna port mode in which it may transmit over multiple antenna ports or single antenna port, mode in which it may transmit over one antenna port. While in multi-antenna port mode, the base station may dynamically signal the WTRU to switch between the configured transmission scheme of the transmission mode and a single-antenna port, scheme in which the WTRU may only transmit over one antenna port. Switching to the single-antenna port scheme is referred to herein as fallback. For each PUSCH transmission, the signaled UL grant from the base station may direct the WTRU to use either the transmission scheme of the configured transmission mode or the single-antenna port fallback scheme. Power headroom may be different upon such change. In accordance with existing R8 reporting rules, the WTRU may not report such a change until the next periodic power headroom report, which .may he too far in the future to enable the base station to make appropriate scheduling choices for the current transmission, scheme, [0049] Described herein are power control methods and apparatus for LTE Release 10 (RIO) or LTE-A that may address bandwidth extension using carrier aggregation, multiple CCs, multiple power amplifiers, uplink multiple-input-multiple-output (UL ΜΙΜΟ), simultaneous PUSOH and physical uplink control channel (PUCCH) transmission, and fallback. The methods include associating CCs with PAs, and configuring and reporting power control parameters rel ated to the CCs and PAs; power headroom reporting for PUSCH, PUCCH, and simultaneous PUSCH and PUCCH transmissions; and computing and reporting power headroom to enable the base station to make informed scheduling decisions- Each of the example methods presented may be used individually or in combination with any one or more of the other example methods, [0050] In the examples described below, the mapping of CCs to PAs may be known by both the WTRU and the base station. If the mapping of CCs to PAs for a WTRU is determined in the base station, the base station may signal the mapping of (J) CCs to (K) PAs to the WTRU, Alternatively, if the mapping of CCs to PAs for a WTRU is determined in the WTRU, the WTRU may signal the mapping of (J) CCs to (K) PAs to the base station. Alternatively, the mapping may be derived by both the WTRU and the base station based on known, defined or pre-established configurations (e.g., by WTRU category and frequency band). The number of the PAs at the WTRU may be derived by the base station implicitly from the WTRU category information (or other indicator) signaled by the WTRU (e.g,, as part of the WTRU capability information). Alternatively, the WTRU may explicitly signal the number of the PAs and their characteristics, (e.g,, maximum transmit power) to the base station, [QGolJ In certain of the examples described below, the WTRU may signal power control data to the eNodeB for one or more (J) CCs using one or more (K) PAs, To illustrate such a mapping, consider the following mapping example between WTRU CCs and PAs as shown in Table 1 below. Three CCs are transmitted using two PAs, (Le., K~2 and </~3), and CC#1 is transmitted by PA#1 and CC#2 and CC#3 are transmitted b}? PA#2,

......................................Table 1.....................

In the examples described herein, Pcc(i,j) represents the required UL transmit power determined by the WTRU for CC j in subframe i before any reduction for a maximum power limitation, [0052] Described herein is an example method for signaling CC-specific maximum power. In the example method, the base station may signal Pm«x. the parameter used to limit the WTRU’s uplink transmission power on a carrier frequency, on a per CC basis to the WTRU. For J OCs, this requires J such values, denoted Pm«*(/) or P-MaxQ).

[0053] In further examples described herein Ρμ«χ{/) and P-Max(j) may be used interchangeably to represent the CC specific maximum transmit power value signaled to the WTRU for each CC j. PcmaxCj) is used to represent the CC specific maximum transmit power value for CC j, which may take into account one or more of the signaled maximum power value, the maximum power of the WTRU power class, maximum power reduction allowances, tolerances, and the like, PcMAxCi) may be referred to as the configured maximum power, configured maximum transmit power, or configured maximum output power for the CC.

[0054] Described herein are example methods for signaling and/or determining PA-specific maximum power. In an example method, each PA k may have a maximum transmit power capability, denoted 1%^· (A), that may be determined by the WTRU , PAmx (k) may be an attribute of the WTRU category. Separate maximum power transmit capability for each PA may be signaled by the WTRU to the base station. For IF PAs, this requires K maximum transmit power capabilities. Alternatively, both the WTRU and the base station may derive the PA specific maximum transmit power capability based on the WTRU category (or other indicator) reported to the base station, by the WTRU in a WTEU capability information element. Additionally, the base station may signal a substitute PA-specifie maximum transmit power capability to the WTRU. The substitute PA-specific maximum transmit power capability may be a value different from the PA property value that may be signaled from the WTRU to the base station as stated above. This may require the WTRU to operate as though the PA had the substitute maximum transmit power capability. The substitute maximum transmit power capability may be less than the maximum transmit power capability which is the property of the PA.

[0055] Described herein are example methods for signaling and/or determining CC-specific power headroom and/or PA-spedfic power headroom. In an example method, separate power headroom reports for each CC and PA may be signaled to the base station by the WTRU. For J CCs and K PAs, this may require J4-K headroom reports. The CC power headroom may be the difference between the CC maximum transmit, power and the required transmit· power for all physical uplink shared channel (PUSCH) transmissions on the CC. The PA power headroom may'be the difference between the PA maximum transmit power and the required transmit power for all PUSCH transmissions at the PA.

[0056] Alternatively, the WTRU may signal the power headroom reports for the J CCs and the base station may derive theJTPA headroom values based on the CCs to PAs mapping, the CC headroom reports, P-Max(/) for each CC _j, and the PA-specific maximum transmit power, [0057] 'Described herein is an example method for signaling CC-specific transmit power and PA-specific transmit power. In the example method, separate transmit powers for each CC and PA may he signaled to the base station by the WTRU. For J CCs and K PAs, this may require J+K transmit power reports. The headroom for CC j in subframe L denoted ^·ίΥ·(0./), may be determined by the base station from the CC transmit powers as:

Equation (1) where PcdiJ) is the required transmit power for PUSCH transmission in CC(/) in subframe i.

[0058] The headroom for PA k in subframe i, denoted PilM (i, k) , may be determined by the base station from the PA transmit powers as:

Equation (2)

where PpA(i,k) is the required transmit power for all PUSCH transmissions in PA(fe) in subframe L

[0059] Described herein is a method for reporting headroom or transmit power. In the example method, the base station may configure the WTRU as to whether transmit power and/or power headroom is reported by the WTRU. The transmit power and/or power headroom may be CC specific and/or PA specific.

[0060] Described herein is a method for signaling CC-specific transmit power. In the example method, the WTRU may signal CC-specific transmit power to the base station and the base station may determine, from the CC-specific transmit powers, the PA-specific headroom. The WTRU may not need to explicitly signal the PA transmit power or headroom. This may require Jrather than J+K transmit power reports, and may reduce the signaling overhead. The PA headroom for PA k in subframe L denoted PmA (ijc) , may be determined from the CC transmit powers and the CC to PA mapping. Using the CC to PA mapping example provided earlier:

Equation (3) Equation (4) and the headroom for the CCs, denoted Pmv (/, j) , may be determined by the base station using Equation 1, copied below for convenience:

Equation (1) [0061] Described herein are example methods for transmit power and/or power headroom reporting for simultaneous FUSCH/PUCCH transmissions. In LTE, PUCCH and PUSCH are transmitted in different subframes in order to primarily preserve the single earner property in UL transmission. In addition, the LTE WTRU reports power headroom based on the PUSCH transmit power. LTE-A, however, may support, simultaneous PUSCH and PUCCH transmissons, where a single WTKU-specific UL CC is configured semi-statically for carrying PUCCH. When simultaneous PUSCH/FUCGH transmission occurs in a subframe (on a CC), the maximum transmit power available for the PUSCH transmission may be reduced by the transmit power allocated to the PUCCH transmission. In this case, it may be desirable to include the PUCCH transmit power value in the transmit power and/or power headroom reporting, since the PUCCH transmission directly afreets the power headroom available for PUSCH. In the example methods described herein, the WTRU may take PUCCH transmit power into account when reporting to the base station the WTRU s power headroom or transmit power in which simultaneous PUSCH and PUCCH transmission occurs on a CC.

[0062] In one example method, if simultaneous PUSCH and PUCCH transmission occurs on CO j, the transmit power and/or headroom of PUSCH and PUCCH may be combined. For transmit power reporting the WTRU may report.:

Equation (5) where Pcc (/, /) may be the required transmit power for PUSCH on CC j in

subframe i (i.e,, the PUSCH power before any reduction for a maximum power limitation) and Pcc n?CCft 0\,/) may be the required transmit power for PUCCH on CC j in subframe i (i.e., the PUCCH power before any reduction for a maximum power limitation). If in subframe i (where PUSCH power headroom may be reported), PUCCH is not present, then the latest required transmit power for PUCCH (i.e., latest PUCCH transmission) on CC 3 may used for P(X, pucai (/, / ),

Alternatively, the downlink control information (DCI) format used for the latest PUCCH transmission may be used to derive Pcr „**&amp;(*> J). Alternatively, a reference DCI format (e.g., DCI format· la) maybe used to derive Pa, nvc}{(i,j) [0063] For power headroom (PH) reporting, the WTRU may report;

Equation (6) where Pcmax© may be the configured maximum power for CC j, (e.g,, carrier specific maximum transmit power) as described earlier. If in. subframe i (where PUSCH power headroom may be reported), if PUCCH is not present, then the latest required transmit power for PUCCH on CC j may used for Pa .

Alternatively, the DO format used for the latest PUCCH transmission may be used to derive Pcc . Alternatively, a reference DO format (e.g., DO format la) maybe used to derive Pcc ^;craf(/,/) [0064] On the other CC(s) (/ Φ j), the WTRU may report the transmit power and/or power headroom of PUSCH, For transmit power reporting, the WTRU may report PccO- J) = Pwj>uscti(i,l) and for power headroom reporting, the WTRU may report Phcc&amp;D ~ PcMAx(/)-PecLPUseH(bO· [0065] In another example method, the WTRU may separate!y/indi vidually report transmit power and/or power headroom reports for PUSCH! and PUCCH!. For transmit power reporting, the WTRU may report: Pc<u5uscB(ij) and Pcxypuixti{ij). For power headroom reporting, the WTRU may report:

and

Equation (?) , Equation (8) where PmxLPusciiiij) and Pttccjwcctfij) may represent the power headroom reports for PUSCH and PUCCH!, respectively, and PUCCH is transmitted on CC j. If in subframe i, (where PUSCH! power headroom may be reported), if PUCCH is not present, then the latest required transmit power for PUCCH on CC j may be used for P(xipucm(ij). Alternatively, the DCI format used for the latest PUCCH transmission may be used to derive PccjwcciifiJ). Alternatively, a reference DCI format (e.g., DCI! format la) maybe used to derivePccj>vccti(iJ). For the other CC(s) (I # j), the WTRU may report the transmit power and/or power headroom of PUSCH on the CC.

[0066] In. another example method, the WTRU may separately report transmit power and/or power headroom for PUSCH as in LTE and for the combination of PUSCH and PUGCH if PUCCH is present on the CC <e.g„ CC j). For transmit power reporting, the WTRU may report (for subframe t) PwjvscuiiJ) and PccfiJ), where PcdiJ) ~ Pccj>uscB(ij) + PccjpvcchGj). For power headroom reporting the WTRU may report Pnccj^usmfiJ}, where

and P'cHX':(i,j) is as shown in Equation δ and copied here for convenience;

Equation (6) where Pumax© may be the configured maximum power for CC j, (e,g., carrier specific maximum transmit power) as described earlier, [0067] Described are example methods for transmit power and/or power headroom reporting when there are multiple PUCCHs per CC, For the case of more than one PUCCH within a CC, Pcnj’UGCH&amp;j) may be replaced with.

, where there are N instances of PUCCH in CC j in subframe L denoted as Ραν ρ(ΧχΉ (h./>«) for n - 0,1,.. .N-1, Alternatively, there may he separate headroom or transmit power reports for each such PUCCH.

[0068] Described are example methods for triggering reports. For simultaneous PUSCH and PUCCH transmission, the power headroom reporting mechanism may be based on timer and/or event triggers, However, the value of the timer and/or event threshold maybe different for PUSCH, PUCCH and/or the combination of PUSCH a nd PUCCH, For a power headroom or transmit power report based on one timer and/or event threshold, the WTRU may report the power headroom or transmit power of the channel which, is associated with the given timer or event threshold. Alternatively, the WTRU may report the power headroom or tra nsmit power of both PU SCH and PUCCH once either channel’s timer expires or the event threshold is exceeded. Alternatively, the WTRU may report power headroom or transmit power of both PUSCH and PUCOH upon triggers from both channels. Alternatively, the WTBU may report PUCCH power headroom along with PUSCH power headroom whenever PUSCH power headroom reporting is triggered, [0069] With regard to which of the above triggers and reporting methods may be used by a WTRU, it may be specified, configured by the base station for all WTRUs in the cell via a system information block (SIB), or configured by the base station individually for each WTRU in the cell via a radio resource control (RRC) message.

[0070] Described herein are example methods for configurable transmit power or power headroom reporting in carrier aggregation situations. The number of PAs with which a WTRU may be equipped may be different depending on WTRU class (or category). In addition, the CC allocation/eonfiguration for a WTRU may be dependent on several factors such as WTRU class, QoS requirement, CC availability, and other like factors. The transmit power or power headroom on a CC maybe close to that on other CC(s), for example, in contiguous CC allocation. Therefore in one example method, the base station may configure the WTRU to report transmit power or power headroom per CC. or per group of CCs (like contiguous CCs), or for all aetive/configured CCs, e.g\, based on the carrier aggregation allocation and/or the WTRU PA configuration, and/or some other system parameters, [0071] Alternatively, the WTRU may autonomously determine which transmit power(s) or power headroom(s) is/are reported, e.g., based on a predefined rule. For example, if

where ε is a predefined threshold and k # n, then send only a single power headroom value for both the kth and nth CC, [0072] Th e a bove condition i mplies that if the difference in power headroom between any CCs is small enough (or less than or equal to a predefined value), then the WTRU may not report transmit power(s) or power headroom(s) on all the associated CCs, rather the WTRU may send a single report which represents all of the CCs, For example, this may he done for the case of contiguous CCs. In this case, the WTRU may report a transmit power or power headroom corresponding to a representative CC (e.g., a middle CC or a CC with lowest (or highest) carrier frequency) among the contiguous CCs.

[0078] Described herein is an example method for signaling CC-speciffc power headroom. The example method may compute a CC-specific power headroom, denoted as P^cc (*»./) > and signal the computed CC-specific headroom to a base station. The example method may not compute CC-specific power headroom in the conventional sense, he., as the difference between requested (nominal based on last UL grant) and maximum CC-specific transmit power. The notation P^. (i, j) may he used to distinguish CC-specific power headroom computed per the example method below from CC-specific power headroom computed in the conventional sense which uses the notation PHCC (/, /) ,

This example method is referred to later as Alternative 1.

[0074] The base station may, by using the signaled CC-specific power headroom computed per the example method, schedule grants that avoid exceeding maximum power in the CCs and avoid exceeding maximum power in the PAs, This may be accomplished without the base station having any knowledge of the number of PAs, PA-specific maximum transmit power, PA-specific headroom, CO-to-PA mapping, or the method used for the calculation.

[0075] The CC- specific headroom P/{CC (/, j ) may be signaled for all,-/ CCs and may require J power headroom reports. Noting that the base station is “unaware” and unaffected that the WTRU is using this method, the CC-specific power headroom Pflcc (/, j) may be signaled as if the value is PHCC (/,./). The trigger for signaling P^cc (r, j) may be similar to that described for Pflcc (/,./), i.e., event based or periodic, where the event is based on the value of Pace 0\ j) rather than Pm,c (/,/).

[0076] Referring to Figure 2, the WTRU initiates computation of Pitcc (C J) (210). The power headroom for CC j in subframe k denoted as pHcc(iJ) [dB], may be determined for all J CCs as described in Equation 1 for PUSCH transmission or for simultaneous PUSCH and PUCCH transmission as described in Equ ation 6, or some other unspecified criteria for CC-speeific power headroom (220), Define Pl’ifcc(iJ) as Pm-cfiJ) in linear rather than dB form, as:

liquation (9) [0077] The power headroom for PA k in subframe i, denoted as PapA (i, k) [dB], may be determined for ail K PAs as described in Equation 2 for PUSCH transmission or for simultaneous PUSCH and PUCCH transmission as described in Equation 6 or some other unspecified criteria for PA-speeiile power headroom (280). Define ΡΛt/PA^k) as P8R4 (/, k) in linear rather than dB form, as:

Equation (10) [0078] The WTRU may then identify those CC(s) with positive linear headroom, be,,

and those CC(s) with negative linear headroom, i.e.,

[0079] For each PA k. the WTRU may then determine the available PA power (250), denoted as P * apa (/, k), as the sum of Pv" hpa (i,k) plus the sum of P‘;ncc(tj) for all CCsy mapped to PA k, and having negative P*ucc(iJ),OT:

Equation (11) or, equivalently:

Equation (12) where

Equation (13).

[0080] For each, PA k, the WTRU may Identify the PA as being one of three cases, denoted as A, B and C below (260). For each such case, the signaled CC-specific power headroom is computed as described, [0081] The case in which the available PA power is positive and greater than or equal to the sum of positive CO-specifie headroom reports is denoted as ease A. For any CCs that per grant computed power may exceed their maximum allowed power, the specific CCs’ actual headroom may he signaled so that the base station may be expected to reduce, by future grant, the CC-specific transmit power to that maximum allowed power. The available PA power may then be the original amplifier headroom plus that power gained by reducing the power of the negative-headroom CCs. In this case, the available power is more than the summed headroom reports of the positive-headroom CCs, so the actual headroom reports for those CCs are also signaled. If the base station were to fully utilize those headroom reports in a future grant, all CCs may be at their maximum transmit power, and the PA may be below its maximum transmit power.

[0082] Referring now also to Figure 3, in case A, for the available PA power, PN am (i, k) , being positive and greater than or equal to the sum of CC-specific power headroom reports for CCs identified as having positive headroom (810), i.e..

Equation (.1.4) or, equivalently:

Equation (15) then for all such CCs, the WTRU may reportPffCC (hi) as equal to Phcc ./) > be., the signaled CC-speelfic headroom is as originally determined (320), [0083] The case in which the available PA power is positive and less than the sum of positive CC-specific headroom reports is denoted as case B and is also shown in Figure 3. For any CCs that per grant may exceed their maximum allowed power, their actual headroom may be signaled so that the base station may be expected to reduce, by future grant, the CC-specific transmit power to that maximum allowed power. The available PA power may then be the original amplifier headroom plus that power gained by reducing the power of the negative-headroom CCs. In this case, the available power is less than the summed headroom reports of the positive-headroom CCs, so the signaled headroom reports for the positive-headroom CCs are their actual headroom reports reduced by some amount such that all of the available PA power is apportioned amongst those CCs. If the base station were to fully utilize those headroom reports in a future grant, the formerly negative-headroom CCs may be at their maximum transmit power, the formerly positive-headroom CCs may be at some higher (though below their maximum allowed) transmit power, and the PA may be at its maximum transmit, power.

[0084] In case B, for the available PA power, P * apa ( i, k ) , being positive a nd less tha n the sum of CC-specific headroom reports for CCs identified in Step 3 as having positive headroom (330), i.e,.

Equation (16} or, equivalently;

Equ ation (17) then the WTRU may determine a weighting factor, denoted as cc{i,k), to fully apportion the available power amongst the CCs identified as having positive headroom (335). For illustrative purposes only, one example weighting may be the quotient of the available power and the sum of the positive CC-speeifie power headroom reports, or

Equation ¢18) [0085] Other weightings may be possible (340), e.g., based on relative transmit powers per positive-power headroom CO, in which case there may be a separate weight for each CG j, denoted as j*k) , or

Equation (19) [0086] Notwithstanding the method used to calculate cc(it k), after completing the case B method, the weighting may he computed such that the sum of the power headroom reports of those OC(s) identified as having positive headroom is then equal, to the available power, [0087] For CCs identified as having positive headroom (345), the WTRU may report P’HCC (i,j) as equal toF,!Wcc(i,/)-«(?',λ), or alternatively, e.g„

Pwncc(i,j) a{Uj,k) < converted to dB form, or

Equation (20) or alternatively.

Equation (21) where the reported headroom for the positive-headroom CCs is now lower than or equal to as originally determined (350), [0088] For CCs identified as 'having negative headroom (345), the WTHU may report P^ (i, j) as equal to PiKX(/,/}, i.e,, the signaled CC-specillc headroom as originally determined (355).

[0089] The ease in which the a vailable PA power is negative is denoted as case C and shown in Figure 4. In this case, unlike case A and B, signaling actual headroom for the negative-headroom CCs and the base station reducing their transmit power by future grant yields negative PA available power, i.e., such a grant may “request” that the PA transmit at a power higher than its maximum allowed power. This may be so even if the headroom for the positive-headroom CCs were signaled such that the base station may reduce their transmit power by future grant to zero watts. Therefore, negative headroom reports may be signaled for all CCs such that the base station may reduce the transmit power by future grant of all CCs, such that a PA may he “requested” to transmit only at its maximum power, rather than exceed it.. This .is accomplished by first, similar to cases A and B, considering that if a future grant may reduce the transmit powers of the negative-headroom CCs to their maximums, what may be the resulting negative available PA power, i.e„ a power shortage, and, second, by in some manner apportioning that shortage amongst all CCs such that the PA .may be at its maximum transmit power. The CC-specific headroom reports are computed and signaled such that the base station may, by future grant, request CC-specific transmit powers to achieve this effect, i.e., if the base station were to by future grant reduce all CC-specific transmit powers by their signaled negative headroom reports, all CCs may be below their maximum transmit power and also lower than that requested by the previous grant, and the PA may be at its maximum transmit power, Note that in this case, the signaled headroom reports are computed relative to the transmit power from the previous grant, rather than as relative to the CC-specific maximum transmit power. In either case, the desired effect should he realized.

[0090] In case C, for the available PA power, P" afa {/,£), being negative, i.e.,

then for the CCs (405) identified, as having negative headroom (410), set a first temporary CC-specific transmit power, denoted as Pll icc (/, j), to the maximum per-CC transmit, power (415) and for CCs identified as having positive headroom (410), set the first temporary CC-specific transmit power to the requested CC-specific transmit power (420). Then convert to linear form (425), or,

*

Equation (22)

Equation, (23) [0091] The WTRU may then compute a CC-specific weighting factor (430), denoted as /(/,,/)» from individual weighting factors assigned to each CC, as:

Equation, (24) where t, /) may be a. priority expressed as a numerical value in which the higher the value the higher the priority of the CC. For example, priority may be based on priority of the data or service supported by the CC, CC-specific transmit power, P wicc (i, j), modified by the determination of Pwlcc (0 j) if applicable, some combination thereof or some other criteria.

[0092] Note that

That is, the weighting may be determined such that

and that after determining P" “cc (/,/), the sum of the CC- specific transmit powers is equal to the maximum PA transmit power.

[0093] For all CCs, the WTRU may then compute a reduced second temporary CC-specific transmit power, denoted as-P*~cc(/,j) , where the available power may be apportioned per the factor /(/,,/) (440), or:

Equation (25) [0094] For all CCs, the WTRU may then compute the signaled headroom as the ratio of reduced second CC-speeific transmit power to that of the original requested CC-specific transmit power, in dB (450), or:

Equation (26) [0095] Note that within Case C, the variables first and second “temporary €C-specific transmit power” are intermediate variables used by the method, neither PA nor CC transmit powers are set to these values.

[0096] Described herein is another example method for signaling CC-speeific power headroom. In this example method, the WTRU signals a modified CC-specific headroom, denoted as P'bcc (*»./) below, to the base station for all J CCs. The base station need not know the mapping of CCs to PAs, and the power control algorithm in the base station may be aware of the power headroom in each CC but does not know if the limitation is due to P-Max or Pamax. This example method may foe referred to as Alternative 2.

[0097] The power headroom, denoted as Pmxiij) for CC j in subframe i, may be determined by the WTRU for all J CCs as shown in Equations 7 a nd 8, respectively, for PUSCH transmission or for simultaneous PUSCH and PUCCH transmission.

[0098] The WTRU then determines and signals a modified power headroom for each CC in the subframe as:

Equation (27) P (i k) where lipA · / j§ as described above, and CC j is mapped to PA k.

[0099] Described herein is an example method for power headroom reporting for carrier aggregation when there may be a WTRU maximum power limit. The sum of per component carrier transmit powers may be subject to some maximum transmit power such that raising or lowering the transmit power of one component carrier may impact the ability to raise the transmit power in another component carrier. To account for this maximum transmit power, an example method is included for calculating and signaling of CG-specific power headroom when there is a WTRU maximum power limit.

[00100] For the case of the maximum WTRU transmit power, denoted . being less than the sum of the per-CC maximum transmit powers, ΡΜαχφ. the first example method (Alternative 1) for signaling CC-specific power headroom may result in the WTRU reporting per-CC power headrcoms that may result in the base station scheduling grants that may correspond to WTRU transmit power which exceeds maximum WTRU transmit power. In the first example method, the power constraints are per-CC maximum transmit power, PMax(j)y and per-PA maximum transmit power, PAMAXik·). The base station may, by using the signaled CC-specific power headroom from the WTRU, schedule grants that avoid exceeding maximum power in the CCs and avoid exceeding maximum power in the PAs.

[00101] In the present example method, the base station may, by using the signaled CC-specific headroom from the WTRU, schedule grant» that avoid exceeding maximum power in the CCs and maximum allowed transmit power of the WTRU, and optionally maximum power in the PAs. The mapping of the WTRU to CCs and, optionally, CCs to PAs, may be illustrated by the example shown in Table 2 in which three CCs are transmitted by one WTRU, and the CCs may be mapped to two PAs.

Table 2 [00102] For a given subframe, the nominal transmit power of the WTRU, i.e., before any reduction by a maximum power procedure, in linear form,

[001031 Given, the conventionally computed per-CC headroom(s), Pfi0C¢0 /), and that the base station may schedule a future grant (s) such that the full transmit power capability of the WTRU may be scheduled, the transmit power of the hypothetical future subframe, i+r,, denoted as P*wtru (i -f r) may be

Equation (28) [00104]

wore to exceed Ρ^υΜΑΧ (in linear form), some or all of the reported per-CC power headrooms, PHCc\hJ)» may have to he further reduced to avoid not only exceeding maximum power in the CCs, hut also the maximum, allowed transmit power of the WTRU.

[00105] An example method for modifying the reported per-CC power headrooms from the conventionally calculated headroom, PHa: (1,/) is now described. The modified /%χ(ΐ,/) may be denoted as {*>/) · Initially, define Pwircc(hj) as Pfxxihj) in linear rather than dR, as:

Equation (29) [00106] The WTRU may determine the power headroom for the WTRU in subframe I» denoted as P^Ci) [dR]. Define Pailimi.(i) as in linear form rather than dR form, as

Equation (30) [00107] The WTRU may then identify those CC(s) with positive linear headroom, ie.,

, and those CC(s) with negative linear headroom, i,e..

The available WTRU power, denoted P*Am«v(i), may be determined as Pwn»rw (/) plus the sum of P^ttcdij) for all CCs j having negative or:

Equation (31) or, equivalently:

Equation (32) where

[00108] Using one of the appropriate eases, denoted as eases A, B and C, the WTEU may compute and signal the CC-specific headroom.

[00109] For case A, where the available WTEU power, P^Awmu (t), is positive and greater tha n or equal to the sum of CC-specific headrooms for CCs identified as having positive headroom, Le.,

or equivalently:

then the WTEU, for all CCs, may report ^/cc^'n/) as equal to PfJCC (/, j) .

[00110] For case B, where the available WTEU power, Pw awtxv (/), may be positive and less than the sum of CC-specific headrooms for CCs identified as having positive headroom, i.e,,

or, equivalently: then the WTEU may determine a weighting factor, denoted as u(l), to fully apportion the available power amongst the CCs identified as having positive headroom. For example, one possible such weighting is the quotient of the available power and the sum of the positive CC-specific headrooms, or

Equation (33) [001111 Other weightings are possible, e.g., based on relative transmit powers per positive-headroom CC. In this case, there may be a separate weight for each CC j, denoted as or

Equation (34) [00112] Notwithstanding the particular method used to compute the weighting factor, the weighting may be computed such that the sum of headrooms of those CC identified as having positive headroom(s) are then equal to the available power after computing P" Η(··(··: {i, j) as described below.

[00113] For the CCs identified as having positive headroom, the WTRU may report P” hcc (hj) as equal to Pucr (i,j)a(i), or alternatively, P*hcc (/*,/) ct(i, J), which may be converted to dB form:

Equation (36) or alternatively,

Equation (36) [00114] Note that the reported headroom for the positive-headroom CCs is now lower than or equal to PlAX·.(/,,/), [00115] For CCs identified as having negative headroom, the WTRU may report P%cc (i,./) as equal toPm:c(i,,/), [00116] For case 3, where the available WTRU power, PwAwmu(i) is negative, i.e„

, then the WTRU may, for the CCs identified as having negative headroom, set a first temporary CC-specific transmit power, denoted as , to the maximum per-CC transmit power and for CCs identified as having positive headroom, set the first temporary CC-specific transmit power to the requested CG-specific tra nsmit power. Converting these to linear form:

Equation (3?) Equation (38) [00117] The WTRU may then convert a CC-specific weighting factor, denoted as β{ί, j) .from individual weighting factors assigned to each CC, as:

Equation (39) where w(ij) may be a priority expressed as a. numerical value in which the higher the value the higher the priority of the CC, For example, this may be based on a priority of the data or service supported by the CC. a CC-specific transmit power (P^cciiJ)) modified by negative or positive headroom if applicable, some combination thereof, or some other criteria.

[00118] Noting that

and notwithstanding the method that may be used for CC-specific transmit power, the weighting maybe determined such that the term

and that after computing F'hcc. the sum of the CC-specific transmit powers may be equal to the maximum WTRU transmit power.

[00119] The WTRU may then, for all CCs. compute a reduced second temporary CC-specific transmit power, denoted as P*1 cc (i, j), where the available power is apportioned per the factor /?(/,/) , or

Equation (40) [001201 For all COs, the WTRU may then compute the signaled headroom as the ratio of reduced second CC-speeific transmit power to that of the original requested CC-specific transmit power, in dB. or

Equation (41) [00121] To account for the maximum power of the PAs in addition to accounting for the CC maximum power and the WTRU maximum power, the method may include an option to combine first and last methods for signaling CC-specific power headrooms such that the WTRU signals the one headroom that represents the least amount of headroom available in the WTRU, (i.e,, the worst case scenario). This may correspond to choosing and signaling as the headroom the lower value of .Ρ'/ΛΧ (ό./) and P"HCCij,j}.

[00122] Described herein is an example method for power headroom reporting (PHR) for fallback scenarios. In any given subframe, given N component carriers, the WTRU uses one of the up to 2ΛΝ combinations of transmission schemes. When a PHR trigger occurs, power headroom may be reported by the WTRU for the one transmission scheme combination that coincidently is used at that subframe. For a given CC, power headroom may vary significantly between that experienced in the configured and fallback transmission schemes due to potentially different transmit power requirements between the two transmission schemes. The base station, relying only on power headroom reported for one particular transmission scheme combination, may not have the complete set of information a vailable to make appropriate scheduling decisions for the WTRU.

[00128] In LTE R8, there one is periodic timer and one prohibit timer. Power headroom may he reported when either the periodic timer expires, or there has been a large pathloss change since the previous headroom report, and the prohibit timer has expired.

[001241 In the example method for multiple component carriers, the WTRU may have one combination prohibit timer for each of the 2ΛΝ possible combinations of transmission schemes, replacing, or in addition to, the WTRU (alternatively, CC-speeific) prohibit timer for the WTRU (alternatively, for each CC). Each combination prohibit timer may be set/reset with a different value, or the same value. The set/reset value(s) may be fixed, or configured by the base station signaling a new parameter(s), similar to prohibitPHR*Timer.

[0012ο] When triggered, the WTRU may transmit power headroom concurrently for all component carriers for the current transmission scheme combination, and restart the prohibit timer for that combination, as well as the periodic timer. Whenever the base station changes the WTRU’s transmission scheme combination, the WTRU may send the power headroom for all active (alternatively all configured) component carriers for the new transmission scheme combination, unless prohibited by that combination's prohibit timer (because of a recent power headroom report for that same transmission scheme combination), [00126] For the case of all component carriers configured to be in singleantenna port mode, fallback does not occur, and th us modification of the trigger algorithm as shown results in power headroom being reported as if the modification were not implemented.

[00127] An example implementation of the PHR for fallback is presented in Table 3 as a modification to the power headroom reporting procedure, where the WTRU prohibit timers may he replaced by the combination prohibits timers

Power Headroom Reporting

The .Power Headroom reporting procedure is used to provide the serving eNB with information about the difference between the nominal UK maximum transmit power and the estimated power for UL-SCM transmission. The reporting period , delay and mapping of Power Headroom are defined in gubclause 9.1.8 of [36,133], RRC controls Power Headroom reporting by configuring two types of timers periodhP.HR-Timer and prohibitPHR* Tkner, and by signalling dl-PidhlossChange which sets the change in measured downlink pathless to trigger a PHR [36.331], For N configured component carriers, there are 2ΛΝ separate timers, denoted as prohibitPH&amp;Timerftsc), where tec is an index, e.g., 0<$sc<{2AN), for each of the 2ΛΝ transmission scheme combinations and current ftseis the index of the transmission scheme combination in the current subframe. There is a trigger, denoted as iriggerftec), for each, transmission scheme combination. A Power Headroom Report (PHR) for all configured UL component carriers, active or...................... inactive,(alternatively for all active UL component carriers) shall be triggered for the current transmission scheme combination if any of the following events occur: pmhibUPff.R-Tirmricurrent tsc) expires or has expired and the path loss for any configured, (alternatively active) component carrier has changed more than dl· PathloesChange dl) since the transmission of a PHR when LIE has (XL resources for new transmission; pmhibitPffM-Tirwr(current tsc) expires or has expired and the current transmission scheme is different from the transmision scheme of the previous transmission - per UxUcPlili-Timer expires; • upon configuration or reomfiguration of the power headroom reporting functionality by upper layers [8J, which, is not used to disable the function. if the UE has UL resources allocated for new transmission for this ΤΠ: - if it is the first. UL resource allocated for a new transmission since the last MAC reset, start perirMiicPHM-Timer; - if the Power Headroom report! tig procedure determines that trigger(eurrent tsc) is set or this is the first time that a P.H.E is triggered, and; - if the allocated UL resources can accommodate a PHR MAC control element plus its subheader as a result of logical channel prioritization for all configured (alternatively all active) UL component carriers: • obtain the value of t:h.e power headrooms for all configured (alternatively all active) component carriers from the physical layer; - instruct the Multiplexing and Assembly procedure to generate and transmit, for all configured (alternatively all active) UL component carriers, a PHR MAC control element bused on the value reported by the physical layer; - start or restart perk>dicP.HM~Timen - start or restart pmhibitPHIl-Ti.mer(current tee); - dear trigger for all tsc - else set trigger(currmt tsc) - endif

Table 3 [00128] A diagram illustrating the method of Table 3, which by way of example shows the use of three of the possible 2AN transmission scheme combinations, is shown in Figure 5. As illustrated, an initial PHR for scheme 0 may be transmitted which is followed by another PHR upon expiration of the scheme 0 periodic timer. A scheme 1 PHR is transmitted based on changing to scheme 1. A second PHR is transmitted upon expiration of the scheme 1 periodic timer. However, an event triggered PHR for scheme 1 is prohibited as the scheme 1 timer is still active. Upon changing to scheme 2, an. attempt to tran smit PHR is prohibited due to lack of medium access control (MAC) buffer space. A PHR triggered by the change to scheme 2 is successfully transmitted at a later time.

[00129] Alternatively, the base station may signal separate prohibit timer startup values for each transmission scheme combination, rather than signaling just one prohibit timer startup value. Using one common prohibit timer startup value or the signaling of separate such values may he either fixed or configurable.

[00180] In another method, gi ven that the transmission scheme combination has changed since the previous transmission, and that the transmission scheme combination’s prohibit timer has not expired, rather than sending power headroom for all configured (alternatively all active) component carriers, the WTRU may send the power headroom for the component carriers) with changed transmission seheme(s). Alternatively, for a transmission scheme transition to all configured (alternatively all active) component carriers using the configured transmission schemes, or all configured (alternatively all active) component carriers using the fallback transmission scheme, the WTRU may send power headroom for all configured (alternatively all active) component carriers. Otherwise, the WTRU may send power headroom reports just for the changed component carriers. The use of the methods may he fixed or configurable [00181] The transmission scheme for a fake component carrier may be the fallback scheme rather than the preferred configured scheme. The selection may be configurable, either common for all fake CCs or per component carrier.

[00182] Described herein are additional example methods for carrier aggregation taking into account a WTRU maximum transmit power. When there is a WTRU maximum transmit power, raising or lowering the transmit power of one component, carrier may impact the ability to raise the transit power in another component carrier.

[0018S] In one example method, the WTRU may compute and report power headroom for a CC as if the base station scheduler would respond to only that particular report ed power headroom, an d not change the grants of the other CCs,

For each component carrier, the WTRU may determine the power headroom as the smaller of the headroom with respect to the CC maximum transmit power and the headroom with respect to the WTRU maximum transmit power given that the transmit powers of all other component carriers remain unchanged. In this method, the WTRU reports one PH per CC.

[00134] An example of this method follows. Note that this is a simplified example and as such all effects (such as maximum power reduction (MPR) and others) may not be taken into account. Also note that power headrooms are typically reported in decibel (dB) and watts are used here for ease of illustration.

[00135] Given 2 CCs, CCl and CC2, which, based on their grants, may transmit at 0.75 W and 0,25 W, respectively. Also given are per CC maximum allowed transmit 'powers of 1W and a WTRU maximum allowed transmit, power of 1W. Taking only the per CC maximum into account, each CO appears to have positive headroom. However, since the sum of the powers is 1W, the WTRU has no headroom with respect to the WTRU maximum. The WTRU may report no (0) headroom for both CCs indicating to the base station that it may not increase the grant on one CC without decreasing the grant on the other. In another example, the WTRU limit may he given as 1,5 W, In this example, CCl may be increased 0.25W alone and CC2 may be increased 0.7SW alone. The .maximum the total may be raised is 0.5W. CCl would report headroom based on the CC limit (able to increase another 0.25¾7) and CC2 would report headroom based on the WTRU limit (able to increase another 0.5W). As a variation on this method, the WTRU may determine and report both the power headroom for each CC as described and the power headroom for each CC with respect to its CC maximum power limit. Accordingly, the WTRU may report two power headrooms per CC.

[00136] Alternatively, the WTRU may determine and report power headroom in accordance with both methods above. In this method, the WTRU may report, two power headrooms per CC. This method may use more PHK signaling than the method set forth above, but gives the base station the most complete set of information with respect to power headroom.

[00137] A variant of the above method and of the other methods described herein for which there is a WTEU maximum power limit may be to modify the nominal power headrooms of t he multiple component carriers such that t he base station, may act upon all reported power headrooms and not violate any maximum power constraint. For example, in each of these methods the WTRU may compute power headroom for each CC such that· it may allocate more headroom to higher priority CCs than lower priority. The WTEU may first compute the actual (nominal) headroom for each CC and then adjust the headrooms to report more positive headroom for higher priority component carriers over those of lower priority component carriers. Prioritization may be based on the type of CC, for example primary CC (PCC) may have priority over secondary CC(s) (SCC(s)). Prioritization may, alternatively, follow a rule similar to a maximum power procedure prioritization rule where, for example, PIJOCH has highest priority, PUSCH with uplink control, information (UCI) has next highest and PUTSCH without UCI has lowest priority. In this case, the priority for headroom allocation may be based on which channel(s) the CC is carrying.

[00138] Power headroom may at times be reported for some combination of real and virtual component earners.

[00139] Component carriers transmitted simultaneously with other component carriers can result in intermodulation, and other effects, which can impact maximum transmission power, which in turn can impact per component carrier power headroom, [00140] Methods for computing and reporting power headroom are described herein given that there may be real as well as virtual component, carriers to support the base station in making scheduling decisions. In these methods, the effects due to the presence of the other CCs may include effects due to their transmit powers, intermodidation effects, impact on MPE, and/or the like. The example methods may use look up tables or calculations that are based on the transmit characteristics of the channels on the CCs (such as frequency, number of resource blocks and the like).

[00141] When the WTRU reports a power headroom for a virtual. CC, the WTRU may transmit the power headroom on a real CC where the real CC may be configurable via signaling from t he base station. Alternatively, the WTRU may autonomously determine a real CC tor the virtual CC power headroom transmission. For example, the WTRU may use a real CC having the largest UL grant or the primary UL CC if it has a grant, [00142] Described herein are example methods for power headroom reporting for real CCs, In one example method, for a subframe which may contain both real UL CCs (component carriers with grants) and virtual UL component carriers (active, or configured, component carriers without grants), the WTRU may, for each real CC, compute the power headroom taking into account the presence of (he., the effect s due to the presence of) the other real CCs. The virtual CCs maybe ignored when determining the power headroom for the real CCs. The 'WTRU may report one power headroom for each of the real CCs, This example method may represent the actual state of the WTRU at the time of the headroom report. This method may be applicable whether or not there are any virtual CCs in a given subframe and whether or not power headroom may be reported for virtual CCs in any subframe.

[00143] In another method, for a subframe which may contain both real UL CCs (component carriers with grants) and virtual UL component carriers (active, or configured, component carriers without grants), the WTRU may, for each real CC, compute the power headroom taking into account the presence (i.e., the effects due to the presence) of the other real CCs and the virtual CCs, assuming the virtual CCs are being transmitted with the reference or otherwise specified formats. The WTRU may report one power headroom for each of the real CCs. This method assumes the presence of alt CCs. both real and virtual, and as the presence of additional component carriers tends to raise MPR and lower maximum power, this example method may provide the base station with a conservative estimate of additional power headroom, [00144] Alternatively, the WTRU may compute the power headroom as described in the above two methods, and report both. This method may use more PHR signaling than does each of these methods but may give the base station the most complete set of information for power headroom .

[00145] In another alternative, it may be configurable via signaling from the base station as to whether to report power headroom in accordance with either of the two above disclosed methods. In this way, the base station may obtain the information it needs with only one PHR for each real CC.

[00146] Described herein are example methods for power headroom reporting for virtual CCs. In an example method, for a subframe which may include both real UL component carriers (component, carriers with, grants) and virtual UL component carriers (active, or configured, component carriers without, grants), the WTRU may, for each virtual CC, compute the power headroom taking into account the presence of (Le., the effects due to the presence of) all the real CCs. The other virtual CCs are ignored. The WTEU may report one power headroom for each of the virtual CCs, This method may be most useful for the case of the base station scheduling just, the one additional virtual component carrier (Le., in addition to the real CCs), As the presence of additional component carriers tends to raise MPR and thus lower maximum power, this example method may provide the ba se station with a liberal estimate of power headroom for the virtual CCs.

[00147] In another method, for a subframe which may include both rea l UL CCs (component carriers with grants) and virtual UL CCs (active, or configured, component carriers without grants), the WTRU may, for each virtual CC, compute the power headroom as if none of the other CCs, real or virtual, were present, and report one power headroom for each of the virtual CCs. This example method may be most useful for the case of the base station scheduling only the virtual CC.

[00148] In another example method, for a subframe which may include both real UL CCs (component carriers with grants) and virtual UL CCs (active, or configured., component carriers without grants), the WTRU may, for each virtual CC, compute the power headroom taking into account the presence of (Le., the effects due to the presence of) ail the real CCs and all the other virtual CCs assuming the virtual CCs are being transmitted with the reference or otherwise specified grant(s) or format(s), and report one power headroom for each, of the virtual CCs. This example method may he most, useful for the ease of the base station, scheduling all CCs. As the presence of additional component carriers tends to raise MPR and lower maximum power, this example method may provide the base station with a conservative estimate of power headroom for the virtual CCs.

[00149] In another method, the WTKU computes and reports each virtual CC power headroom as described in one or more of the methods for power headroom reporting for virtual CCs disclosed above. This method requires additional signaling.

[00150] Alternatively, it may be configurable via signaling from the base station as to which method to use for computing and reporting PHB for a virtual CC. In this way, the base station may obtain the information it needs with only one PHR for each virtual CC.

[00151] Described herein are example methods for including the power headroom report(s) in one or more media access control (MAC) packet data units PDUs. In LTE R8, the power headroom control element may be iden tified by a MAC PDU subheader with logical channel ID (LCID) 11010. There are 15 reserved logical cha nnels he., logical chan nels 0101.1 to 11001 (in binary notation) corresponding to LCLDs 11 to 27 in decimal notation.

[00152] In an example method, the reserved logical channels may be re-used in support, of CC specific or PA specific power headroom reporting. As paid of a MAC configuration RRC message exchange between the base station and the WTRU, a mapping between the CC and the PH reporting logical channels maybe defined. The WTRU may construct PH reports based on the mapping between the CC and PH reporting logical channels provided by the base station. Alternatively, the WTRU may autonomously define the mapping and communicate this mapping to the base station using an RRC message, for example.

[001531 The LTE R8 power headroom MAC control element consists of 1 octet. In the example method, the 6 least significant bits may be used for the actual PH report and the 2 most significant, bits may be reserved. In an alternative method, the CC-specifie and/or PA-specific PH may be reported by defining several 6-bit combinations from the 8 bit set. There are 28 combinations of 6 bits in 8 bits. A mapping between PH 6-bit combinations and CC or PA may be exchanged between, the base station and the WTRU, The WTRU may then use for each CC, the corresponding 6-hit combinations to report the power headrooms.

[00154] Described herein are example methods for controlling power headroom reporting. In LTE R8, the MAC power headroom reporting may be triggered by three main events. In one case, the MAC power headroom reporting may be triggered when the PROHIBITJ?HRJTIMBR expires or has expired and the path loss has changed more than DL_PathlossCh.an.ge dB since the last power headroom report, and the WTRU has UL resources for a new transmission. In the second case, the MAC power headroom reporting may be triggered when the PEEIODIC..PHE..TIMER expires, in which case the PHR is referred to as ‘‘Periodic PHR”. In the third case, the MAC power headroom reporting may be triggered upon configuration and reconfiguration of a Periodic PHR.

[00156] In an example method for controlling power headroom reporting, the reporting methods described above may be applied on a CC basis and/or on a PA basis. The MAC configuration for PH reporting purposes (which may include PERIODIC. PHR. TIMER, PROHIBIT.. PHR.. TIMER, DL...Pathloss€hange threshold) may be provided to the WTRU by the base station on a CC basis and/or on PA basis. Upon the reception of these configurations, the WTRU may apply them, i.e., use them for determining when to trigger PH reporting, on a CC basis and/or on PA basis.

[00156] In another method for controlling power headroom reporting, the WTRU may control CC-specific and/or PA-specific PH reporting on a group basis, i.e., CCs and/or PAs may be grouped for the purpose of PH reporting control. The WTRU may autonomously or in coordination with the base station may decide the grouping. The set of CCs and/or PAs that are within the same group are PH reported using the same reporting configuration parameter set (which may include PERIODIC JPHRJTIMEK, PROHIBIT PHRJHMEE, DLJPathlossChange threshold) or a subset. The group may be the complete set of the CCs and/or PAs.

[00157] In another method for controlling power headroom reporting, the control of the PH reporting may be done using a combination of the two alternative methods above.

[00158] The methods may also include .methods for disabling power headroom reporting on a CC basis, PA basis, or a combination of CCs and/or PAs basis. Upon indication from a base station or autonomous determination by the WTRU, the WTRU may disable PH reporting for the relevant CCs and/or PAs.

[00159] Described herein are example methods for RRC configuration of MAC for power headroom reporting. The RRC protocol may be updated to configure the MAC such that the CC and/or PA PH reporting algorithm(s) described above may he supported. In one method, the LTE R8 MAC configuration IE (MAC-MainConfiguration) may be replicated for each CC and/or each PA. In another method, the PH configuration IE (phr-Configuration) within the LTE R8 MAC configuration IE (MAC-MainConfiguration) may be replicated per CC and/or per PA. In another method, RRC protocol updates may include system information blocks (SIBs) update in support, of CC specific maximum power and/or PA specific maximum power as described herein.

[00160] Embodiments [00161] 1. A method of reporting power headroom for simultaneous physical uplink shared channel (PUSCHl/physicai uplink control channel (PUCCH) transmission occurring on a component carrier, comprising determi ning a power headroom based on at least a PUSCH transmit power and a PUCCH transmit power.

[00162] 2, The method of embodiment 1, further comprising transmitting the power headroom.

[001631 3. The method of any of the preceding embodiments, further comprising deriving the PUGCH transmit power from a reference format in the absence of a PUGCH transmission.

[00164] 4, The method of any of the preceding embodiments, wherein the reference format is a downlink control information format 1A, [00165] 5. The method of any of the preceding embodiments, further comprising determining a PUSCH power headroom.

[00166] 6. The method of any of the preceding embodiments, further comprising transmitting the PUSCH power headroom.

[00167] 7. The method of any of the preceding embodiments, further comprising determining a power headroom based on at least a PUSCH transmit power for a component carrier not transmitting simultaneous PUSCH/PUCGH transmission.

[00168] 8. The method of any of the preceding embodiments, wherein the power headroom is the difference between the component carrier maximum transmit power and the PUSCH transmit power and the PUGCH transmit power, [00169] 9. The method of any of the preceding embodiments, further comprising transmitting the power headroom for all component carriers for a current transmission scheme combination upon a trigger.

[00170] 10, The method of any of the preceding embodiments, further comprising restarting a prohibit and periodic timer for the transmission combination scheme, [00171] 11, The method of any of the preceding embodiments, wherein the all component carriers are one of configured component carriers or active component carriers.

[00172] 12. The method of any of the preceding embodi ments, wherein reporting power headroom is triggered upon expiration of a prohibit, timer and the current transmission scheme is different from a transmission scheme combination of a previous transmission.

[001731 13, The method of any of the preceding embodiments, further comprising receiving a separate prohibit timer startup value for each transmission scheme combination, [00174] 14. The method of any of the preceding embodiments, wherein determining the power headroom further comprises determining a PUSCH power headroom.

[00175] lo. The method of any of the preceding embodiments, further comprising determining a PUCCH power headroom.

[00176] 16. The method of any of the preceding embodiments, further comprising controlling power headroom reporting on a group basis, wherein the group includes at least one of component carriers and power amplifiers.

[00177] 17. The method of any of the preceding embodiments, wherein the group is determined by a wireless transmit/receive unit.

[00178] IS. The method of any of the preceding embodiments, further comprising receiving the group from the base station.

[00179] 19. The method of any of the preceding embodiments, wherein the group uses one reporting configuration for all members of the p*oup.

[00180] 20, A method for controlling power headroom reporting, comprisin g determining a group of a t least one of component carriers and power amplifiers.

[00181] 21. The method of embodiment 20, furt her comprising controlling power headroom reporting using the group.

[00182] 22. The method of any one of the embodiments 20-21, wherein the group is determined by one of a wireless transmit/receive unit or a base station.

[00183] 23, The method of any of the em bodiments 20-22, wherein the group uses one reporting configuration for all members of the group.

[00184] 24. A wireless transmit/receive unit (WTETJ) implementing a method of reporting power headroom for simultaneous physical uplink shared channel (PUSCH)/physical uplink control channel (PUCCH) transmission occurring on a component carrier, comprising a processor configured to determine a power headroom based on at least a PUSGH transmit power and a PUCCH transmit power.

[00185] 25, The WTRU of embodiment 24, further comprising a transmitter configured to transmit the power headroom.

[00186] 26. A wireless transmit/receive unit implementing a method for controlling power headroom reporting, comprising a processor configured to determine a group of at least one of component carriers and power amplifiers, [00187] 27. The WTRU of embodiment 26, further comprising a processor configured to control power headroom reporting using the group.

[00188] 28. A method for reporting power headroom in wireless communications, the method comprising determining power headroom (PH) on a power amplifier (PA) basis and on a component carrier (CC) basis.

[00189] 29. The method of embodiment 28. further comprising transmitting the determined PH in a report.

[00190] 30. The method of any of embodiments 28-29, further comprising receiving control signals in response to the transmitted report.

[00191] 31, The method of any of embodiment s 28-30, wherein a wireless transmission is made on at least one (J) component carrier (CC) using at least one (fe) power amplifier (PA).

[00192] 32. The method of any of embodiments 28-31, wherein the PH is determined for a CC mapped to a PA.

[00193] 38. The method of any of embodiments 28-32, wherein an evolved Node B (eNB) either stores the mapping for each CC to a wireless transmit/receive unit (WTRU) PA on a pre-determined basis or determines the mapping and signals the mapping to the WTRU.

[00194] 34. The method of any of embodiments 28-33, wherein the mapping is based on known pre-established configurations defined by wireless transmit and receive unit (WTRU) category and frequency hand.

[00195] 35. The method of any of embodiments 28*34, where the eNB determines the mapping, either the eNB implicitly determines the number of PAs at the WTRU from WTRU category information signaled as a part of the WTRU capability information, or the number of PAs and their characteristics including maximum transmit power, is directly signaled to the eNR in the report.

[00196] 36, The method of any of embodiments 28-35, wherein the processor determines the PH for a CC mapped to a PA and transmits the mapping to the eNB.

[00197] 37, The method of any of embodiments 28-36, wherein a CC specific maximum power parameter P-Max. is signaled on a per component carrier basis to limit a WTRU uplink transmission power, [00198] 38. The method of any of embodiments 28-37. where P-Max is not signaled, CC specific maximum transmit power at a wireless transrait/receive unit (WTRU) is set to a maximum power as per WTRU capability taking into account applicable Maximum Power Reduction (MPR) and band-edge considerations.

[00199} 39. The method of any of embodiments 28-38, wherein CC specific maximum transmit power configuration, is substituted by any of: extensions of System Information Block! (SIBl), SIB3, SIB5 and SIB7 including allowed maximum transmit power per CC, where an information element (IE) in SIBl includes either an explicit mapping between CC n umber and maximum transmit power or implicit mapping with the order in which the maximum allowed power values are signaled mapping to the order in. which the supported CC are signaled.

[00200] 40. The method of any one of embodiments 28-39, wherein supported downlink (DL) CC are signaled in SIBl.

[00201] 41. The method of any of embodiments 28-40. wherein the explicit signal mapping is represented as: P-Maxlnfo - ((CC„1, P-Max„l), (CC„2, P-Max_2),....,(GO_t/, P-Max„<·/)} where J denotes the total number of carriers supported and being detailed to a specific WTRU.

[00202] 42. The method of any of embodiments 28-41, wherein the implicit signal mapping is represented as: P-Maxlnfo - {P-Max..1, P-Max. 2,..,., P-Max„J), where component carriers are signaled or known in an order corresponding to CC_1, CC__2, ,,,., CC_«/> and P-Max_l is a .maximum allowed power level of CCJL, P-Max„2, a maximum allowed power level of CC„2, and P-

Max„«7, a maximum al lowed power level of CC_</ where the order in which. P-Max. values are signaled, map the order in which the carrier component s are signaled or known.

[00203] 43. The method of any of embodiments 28-42, wherein the mapping is represented as: P-Max„l is a maximum allowed power level of CCLJ while P-Max„«/is the maximum allowed power level of CC„1 assuming the order in which P-Max values are signaled, map the reversed order in which the carrier components are signaled or known.

[00204] 44, The method of any of embodiments 28-43, wherein System Information Blocks are replicated to be on a component carrier basis and P-Max is signaled similarly for each component carrier, [00205] 46. The method of any of embodiments 28-44, wherein P-max values are expressed in terms of either absolute values or relative values with respect to reference P-Max value, and upon receiving signaling, applying CC-specifie maximum power values either immediately or as per SIB modification period rule.

[00206] 46. The method of any of embodiments 28-45, wherein a power amplifier (PA) specific maximum power parameter is signaled where a PA (&amp;) has a maximum transmit power capability, denoted ?^^as determined by a wireless transmit and receive unit (WTRU) and ^amax^ is an attribute of WTRU category.

[00207] 47, The method of any of embodiments 28-46, wherein a separate maximum, power transmit capability for each PA is signaled and foriCPAs, iTis a maximum transmit power capability.

[00208] 48, The method of any of embodiments 28-47, wherein a wireless transmit and receive unit (WTRU) and eNB derive PA specific maximum transmit power capability based on WTRU category indicator reported to the eNB by the WTRU in a WTRU capability information element (I E).

[00209] 49. The method of any of embodiments 28-48, wherein a substitute PA-specific maximum transmit power capability is signaled from an eNB to WTRU and the substitute capability is of a different value than, that of a PA value signaled from a WTRU to an eNB, [00210] 50, The method of any of embodiments 28-49, wherein the substitute capability requires a WTRU to operate as though the PA had the substitute maximum transmit power capability, where the substitute capability may be less than the maximum tra nsmit power capability of the PA.

[00211] 51. Hie method of any of embodiments 28-50, wherein component carrier specific power headroom (PH) and power amplifier (PA)-specific Power Headroom (PH) are signaled separately.

[00212] 52, The method of any of embodiments 28-51, for J CCs and K PAs, requires J+K headroom reports and CC power headroom is a difference between CC maximum transmit power level and the required transmit power for a Physical Uplink Shared Channel (PUSCH) transmission in the CC and PA power headroom is the difference between PA maximum transmit power level and required transmit power for all PUSCH transmissions in a PA.

[00213] 53, The method of any of embodiments 28-52, where only PH for J CCs is signaled and K PA headroom based on the CCs to PAs mapping, the CC headroom, parameter (P-MaxO)) for each CC„J, and PA-specific maximum transmit power leading to K headroom reporting are derived from the signaled PH for J CC.

[00214] 54, The method of any of embodiments 28-53, wherein separate transmit power levels for each CC and PA are signaled.

[00215] 55, The method of any of embodiments 28-54, wherein for J CCs and K PAs, J+K transmit power reports are signaled and PH for CC j in subframe i, denoted '? |s determined from CO transmit power level, as given by: where Pcdi,j) is a required transmit power for Physical Uplink Shared CHannel (PUSCH) transmission in CC© in subframe L· [00216] 56. The method of any of embodiments 28-55, wherein for J CCs and K PAs, J+K transmit power reports are signaled and PH for PA k in subframe i, denoted

is determined from PA transmit power levels, as given by:

where Ppa (i-M is a required transmit power for all Physical Uplink Shared CHannel (PUSCH) transmissions in PA(£) in subframe i.

[00217] 57. The method of any of embodiments 28-56, wherein for reporting Headroom or Transmit Power, an evolved NodeB (eNB) configures a wireless tmnsrait/reeeive unit (WTRU) irrespective of whether transmit (Tx) power and/or power headroom (PH) is reported by the WTRU where Tx power and PH may be CC specific and/or PA specific.

[00218] 58. The method of any of embodiments 28-57, wherein only CC-specific transmit power is signaled and an evolved eNode'B (eNB) determines from the signaled CC-speeifie transmit power, PA-specific headroom, without explicitly signaling the PA transmit power level or headroom.

[00219] 59. The method of any of embodiments 28-58, wherein only J transmit power reports are signaled.

[00220] 60. The method of any of embodiments 28-59, wherein headroom for PA k in subframe L denoted (*’>*) is determined from the CC transmit power level and the CC to PA mapping as;

[00221] 61. The method of any one of embodiments 28-60, wherein headroom for the CCs, denoted ace'**·** . is determined as: Pmxiijj-P-

Max(j)'Pcc(iJ) where Pec(i, j) is the required transmit power for PUSCH transmission in CC (?) in subframe i, [00222] 62. The method of any of embodiments 28-61, wherein for PH reporting in case of simultaneous Physical Uplink; Shared Channel/Physical Uplink Control Channel (PUSCH/PUCCH) transmission in a subframe on a component carrier basis, maximum transmit power available for the PUSCH transmission is reduced by an amount of transmit power allocated to the PUCGH transmission and PUOCH power is factored into account for PH reporting in subframes in which simultaneous PUSCH and PUCGH transmission occurs, [00223] 63, The method of any of embodiments 28-62, wherein a separate report for PH is made for PUSCH and PUCCH respectively.

[00224] 64, The method of any of embodiments 28- 63, wherein an evolved

NodeB (eNB) configures transmit (Tx) power-PH reporting in carrier aggregation.

[00225] 65. The method of any of em bodiments 28-84, wherein the eNB configures the wireless transmit and receive unit (WTRU) in response to any of: number of PAs with which a WTRU is equipped may be different depending on WTRU class (category); component carrier (CC) configuration for a WTRU would be dependent on factors including WTRU class. Quality of Service (QoS) requirement, CC availability; or transmit power-PH on a CC maybe close to that on other CCs for contiguous CC allocation, [00226] 86. The method of any of embodiments 28-65» wherein the eNB configures the WTRU to report Tx power-PH either on a per CC basis, or on a per group of CCs basis or over all aetive/configured CCs based on carrier aggregation allocation and/or the WTRU PA configuration, and other system parameters.

[00227] 67, The method of any of embodiments 28-86, wherein the WTRU as an alternate autonomously determines which Tx power(s)-PHs are reported, [00228] 68, The method of any of embodiments 28-29, wherein the difference in power between any’· CCs is less than or equal to a predefined value, then WTRU does not report. Tx power(s)-PHs on ail the associated CCs but the WTRU signals a single report representing all the CCs.

[00229] 89, The method of any of embodiments 28-68, wherein for a case of contiguous component carriers, the WTRU report a Tx power-PH corresponding to a representative CO where the representative CC is a middle CC or a CC with lowest or highest, carrier frequency, [00230] 70. The method of any of embodiments 28-69, wherein a Medium

Access Control (MAC) Packet Data Unit (PDU) subheader with logical channel ID (LCID) 11010 is used for identifying the PH control element and a set of 15 reserved logical channels is re-used for CC specific or PA specific PH reporting.

[00231] 71, Th e method of any of embodiments 28-70, wherein the logical, channel are reserved from locations 01011 to 11001 binary, corresponding to LCIDs 11 to 27 decimal,

[00282] 72, The method of any of embodiments 28-71, for MAC configuration, Radio Resource Control (RRC) message exchanges between evolved NodeB (eNB) and wireless transmit and receive unit (WTRU), a mapping between CC a nd PH reporting logical channels is further defined and the WTRU constructs the PH reports based on the mapping between the CC and PH logical channels provided by the eNB,

[00233] 73, The method of any of embodiments 28-72, wherein the WTRU autonomously defines the mapping and signals the defined mapping to the eNB by way of a RRC message.

[00234] 74, The method of any of embodiments 28-73, wherein CC-specific and PA-specific PH are defined by several 8-bit combinations from an 8-bit set and the WTRU reports CC-specific and PA-specific PH by defining several 6-hit combinations from the 8-bit set.

[00235] 75, The method of any of embodiments 28-74, wherein a MAC reporting algorithm is controlled for PH reporting, and the control comprises any oft applying the MAC reporting a lgorithm on CC 'basis and on PA basis; applying the MAC reporting algorithm on a group basis where WTRU CC-specific and PA-specific PH grouping is applied; and applying the MAC reporting algorithm on an individual and group basis.

[00236] 76, The method of any of embodiments 28-75, wherein the MAC reporting algorithm includes conditions optimized for reporting and includes any of the following reporting parameters: a PROHIBITJPHRJIIMER; a PERIODIC PHR TIMER; a Periodic PHR: or configuration and reconfiguration of the Periodic PHR.

[00237] 77, The method of any of embodiments 28-78, where the MAC reporting algorithm is applied on CC basis and on PA basis, the MAC configuration for PH reporting is provided to the WTRU by the eNB on CC basis and on PA basis, and upon the reception of these configurations, the WTRU may also apply them on CC basis and on PA basis,

[00238] 78. The method of any of embodiments 28-77, wherein the MAC reporting algorithm is applied on a group basis where WTRU CC-spedfic and PA-specific PH grouping is applied, CCs and PAs are grouped for the purpose of PH reporting control and the WTRU autonomously or in coordination with the eNB decides upon the grouping where the set of CCs and PAs within the same group are PH reported using the reporting configuration parameters.

[00239] 79. The method of any of embodiments 28-78, wherein a provision for disabling PH reporting in CC basis, PA basis, or a combination off CCs and PA basis is provided where the either the eNB indicates or the WTRU determines autonomously and disables PH reporting for the relevant CCs and PAs, [00240] 80. The method of any of embodiments 28-79, wherein a Radio Resource Control (RRC) layer reconfigures a Medium Access Control (MAC) layer for PH reporting and the RRC layer protocol is updated to configure the MAC such that the CC and PA PH reporting procedures are supported.

[00241] 81. The method of any of embodiments 28-80, wherein the reconfiguration includes: a MAC configuration Information Element (IE) MAC-MainConfiguration is replicated for each CC and each PA: a PH! configuration IE PH reporting-Configuration included within existing MAC configuration IE, MAC-MainConfiguration and replicated on a per CC and per PA basis; other RRC protocol updates may include System Information Block (SIB) updates in support of CC specific maximum power and PA specific maximum power, [00242] Although features and elements are described above in particular combinations, one of ordinary skill In the art wil l appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such, as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may he used to implement a radio frequency transceiver for use in a WTRU, 'UE, terminal, base station, RNC, or any host computer.

Claims (18)

1. THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS;

   1, A wireless trausnfit/receive unit (WTRU), the WTRU comprising: a processor configured to: calculate a physical uplink control channel (PUCCH) transmit power associated with a reference downlink control information (DC!) format in the absence of a PUCCH transmission; determine a power headroom using a physical uplink shared channel (PUSCH) transmit power and the PUCCH transmit power; and send the power headroom.
2. 2, The WTRU of claim I, wherein the processor is further configured to determine that the WTRU is configured for simultaneous PUSCH / PUCCH transmission.
3. 3, The WTRU of claim 1, wherein the power headroom is a first power headroom, the PliCSH transmit power js a first PUSCH transmit power, and the processor is further configured to: determine a second power headroom using a second PUSCH transmit power; and send the first power headroom and the second power headroom in the same subframe,
4. 4, The WTRU of claim 3, wherein the first power headroom is for a carrier, the second power headroom is for the carrier, the first PUSCH transmit power is for the carrier, and the second PUSCH transmit power for the carrier.
5. 5, The WTRU of claim 3 , wherein the first power headroom is tor a first carrier, the second power headroom is for a second carrier, the first PUSCH transmit power is for the first carrier, and the second PUSCH transmit power is for the second carrier..
6. 6. The WTRU of cl aim i, wherein the processor is further configured to determine that a carrier lias a PUSCH transmission in a subframe.
7. 7. The WTRU of claim 1, wherein the processor is further configured to determine a maximum power for a carrier.
8. 8. The WTRU of claim 7 , wherein the maximum power for the carrier is the WTRU configured maximum output power for the carrier,
9. 9. The WTRU of claim 1, wherein the power headroom is for a.primary cell.
10. 10. The WTRU of claim 1, wherein the reference DO format is a DO forma t l A. 1.1. flic WTRU of claim 1, wherein the processor is configured to determine the power headroom using the PUSCH transmit power and the PUCCH transmit power by: determining a maximum transmit power for a carrier; and calculating the power headroom using the maximum transmit power for the carrier, the PUSCH transmit power, and the PUCCH transmit power, 12. A. method for reporting power headroom, the method comprising: calculating, by a wireless transmit/receive unit (WTRU), a physical uplink control channel (PUCCH) transmit power associated with a reference downlink control information (DC!) format in the absence of a PUCCH transmission; determining a power .headroom using a physical uplink shared channel (PUSCH) transmit power and the PUCCH transmit power; and sending the power headroom.
11. 13, The method of claim 12, further comprising determining that the WTRU is configured for simultaneous PUSCH / PUCCH transmission.
12. 14. The method of claim 12, wherein the power headroom is a first power headroom, the PUSCH transmit power is a first PUSCH transmit power, and the method further compri ses: determining a second power headroom using a second PUSCH transmit power; and sending the first power headroom and the second power headroom in the same subframe.
13. 15. The method of claim 14, wherein the first power headroom is for a carrier, the second power headroom is for the carrier, the first PUSCH transmit power is for the earner, and the second PUSCH transmit power for the earner.
14. 16. The method of claim 14, wherein the first power headroom is 'for a. first carrier, the second power headroom is for the second carrier, the first PUSCH transmit power is for the first carrier, and the second PUSCH transmit power is for the second carrier,

    7. The method of claim 12, further comprising determining a carrier has a PUSCH transmission hi a sub frame,
15. 18, The method of claim 12, further comprising determining a maximum power for a carrier.
16. 19. The method of claim 18, wherein the maximum power for the carrier is the WTRIJ configured maximum output power for the carrier, .20. The method of claim 12, wherein the power headroom is for a primary cell.
17. 21. The method of claim 12, wherein the reference DC I format is a DC! format 1A.
18. 22, The method of claim 52, wherein determining the power headroom using the PUSCH transmit power and the PUCCH transmit power comprises: determining a maximum transmit power for a carrier; and calculating the power headroom using the maximum transmit power for the carrier, the PUSCH transmit power, and the PUCCH transmit power.