JP5784181B2 - Method for transmitting a power headroom report in a wireless communication system - Google Patents

Description

  The present invention relates to a radio communication system and a terminal for providing a radio communication service, and further, an E-UMTS (Evolved Universal Mobile Systems System) or a LTE system in an E-UMTS (Evolved Universal Mobile Systems System) or a LTE system. More particularly, the present invention relates to a method of effectively transmitting a power headroom report (PHR) from a terminal to a base station.

  FIG. 1 is a diagram illustrating a network structure of E-UMTS, which is a mobile communication system to which the related art and the present invention are applied. The E-UMTS system has evolved from the conventional UMTS system and is currently undergoing basic standardization work in 3GPP. The E-UMTS system can also be called an LTE system.

  The E-UMTS network is divided into E-UTRAN and CN. E-UTRAN is a terminal (hereinafter referred to as “User Equipment (UE)”), a base station (hereinafter referred to as “eNode B”), and a serving gateway (Serving Gateway; S-) that is located at the end of the network and connected to an external network. GW) and a mobility management entity (MME) that manages UE mobility. One eNode B has at least one cell.

  2 and 3 show the structure of the radio interface protocol between the UE and the base station in accordance with the 3GPP radio access network standard. The radio interface protocol is composed of a physical layer, a data link layer, and a network layer in the horizontal direction, and a user plane for transmitting data information and a control plane for transmitting control signals in the vertical direction. . The protocol layer is based on the lower three layers of the Open System Interconnection (OSI) standard model well-known in the communication system, based on the first layer (L1), the second layer (L2), the third layer ( L3).

  Hereinafter, each layer of the radio protocol control plane of FIG. 2 and the radio protocol user plane of FIG. 3 will be described.

  The physical layer of the first layer (L1) provides an information transfer service (Information Transfer Service) to an upper layer using a physical channel. The physical layer is connected to a medium access control (MAC) layer, which is an upper layer, via a transport channel, and data moves between the MAC layer and the physical layer via the transport channel. Data moves between different physical layers, that is, between the physical layer on the transmission side and the reception side via a physical channel.

  The second MAC layer provides services to the upper radio link control (RLC) layer via a logical channel. The second layer RLC layer supports reliable data transmission. The PDCP layer of the second layer is an IP packet header size that includes control information that is relatively large and includes unnecessary control information in order to efficiently transmit in a wireless section with a small bandwidth when transmitting an IP packet such as IPv4 or IPv6. Execute header compression function to reduce

  The radio resource control (RRC) layer located at the highest level of the third layer is defined only in the control plane, and is related to the setting, reconfiguration and release of the radio bearer (RB). And is responsible for controlling physical channels. Here, RB means a service provided by the second layer (L2) for data transmission between the UE and the UTRAN.

  As described above, the base station and the UE are the two main entities constituting the E-UTRAN. Radio resources in one cell are composed of uplink radio resources and downlink radio resources. The base station is responsible for allocation and control of the uplink and downlink radio resources of the cell. That is, the base station determines which UE uses which radio resource at which moment. For example, the base station may decide to allocate a frequency of 100 Mhz to 101 Mhz to User 1 for downlink data transmission for 3.2 seconds. In addition, when the base station makes such a determination, the base station notifies the UE of the fact and causes the UE to receive downlink data. Similarly, the base station determines when and which UE uses which radio resource and how much data to transmit on the uplink, informs the UE of this determination and informs the UE during the time Send data using resources. In the prior art, one terminal continuously uses one radio resource while a call is connected. This is unreasonable considering that many services are now based on IP packets. This is because most packet services do not generate packets continuously during the call connection time, and there are many sections in which nothing is transmitted during the call. Nevertheless, it is inefficient to allocate radio resources to one terminal in succession. In order to solve this, the E-UTRAN system uses a scheme in which radio resources are allocated to the UE in such a manner only when the UE is required or when there is service data.

  In general, dynamic radio resource scheduling is a method of notifying about radio resources used every time a UE transmits and receives. FIG. 4 is a diagram illustrating an example of the operation of dynamic radio resource allocation. Usually, an uplink radio resource assignment (eg, UL GRANT) message or a downlink radio resource assignment (eg, DL ASSIGNMENT) message is transmitted in a PDCCH (Physical Downlink Control Channel). Therefore, the UE receives or monitors the PDCCH every designated time. Upon receiving the UE identifier (eg, C-RNTI), the UE receives or transmits the radio resource indicated in UL GRANT or DL ASSIGNMENT transmitted on the PDCCH, and data transmission and reception between the UE and the eNode B are performed. Use radio resources to do so.

  More specifically, in the LTE system, in order to use radio resources efficiently, the base station must know what data each user wants to transmit and how much. In the case of downlink data, the downlink data is transmitted from the connection gateway to the base station. Therefore, the base station can grasp how much data should be transmitted to each user in the downlink. On the other hand, in the case of uplink data, if the UE does not notify the base station of information about data that the UE intends to transmit directly on the uplink, the base station needs how much uplink radio resources each UE needs. I do not know what to do. Therefore, each UE must provide the base station with the information necessary for the base station to schedule radio resources so that the base station can properly allocate uplink radio resources to the UE.

  For this, the UE notifies the base station of any data that needs to be transmitted, and the base station transmits a resource allocation message to the UE based on this information.

  In the above process, that is, when the UE notifies the base station that there is data to transmit, the UE notifies the base station of the amount of data stored in the buffer of the UE. This is referred to as a buffer status report (BSR).

  The BSR is generated in the form of a MAC control element, is included in a MAC protocol data unit (PDU), and is transmitted from the UE to the base station. That is, uplink radio resources are required to transmit BSR. This means that uplink radio resource allocation request information for transmitting the BSR is transmitted. When the BSR is generated, if there is an allocated uplink radio resource, the UE transmits the BSR using the uplink radio resource. The process in which the UE transmits the BSR to the base station in this way is called a BSR process. The BSR process is as follows: 1) When there is no data in all the buffers, if new data arrives in one buffer, 2) the data arrives in an empty buffer, and the priority of the logical channel related to the buffer is When the priority is higher than the priority of the logical channel related to the buffer storing the data, 3) Start when the cell is changed. However, when an uplink radio resource is allocated when the BSR process is triggered, all data in the buffer can be transmitted with the radio resource, but when the radio resource is insufficient to further include a BSR, The UE cancels the triggered BSR process.

  Here, apart from the BSR, there is a power headroom report (PHR). The power headroom report informs how much power the terminal can use additionally. That is, the PHR can indicate a power offset between the maximum transmittable power of the terminal and the current transmission power. This can also be defined as the difference between the nominal maximum UE transmit power and the estimated UL-SCH transmit power.

  The reason why the terminal notifies the PHR to the base station is to allocate an appropriate amount of radio resources to the terminal. For example, it is assumed that the maximum transmission power of the terminal is 10 W, and that the terminal is currently using an output of 9 W using a frequency band of 10 Mhz. In order to allocate a frequency band of 20 Mhz to the terminal, 18 W (9 W × 2) of power is required. However, since the maximum power of the terminal is 10 W, when the 20 MHz band is allocated to the terminal, the terminal cannot use the entire frequency band or power is insufficient, and the base station normalizes the signal of the terminal. Can not be received.

  In the state of the art, most current communication traffic is based on Internet services. One of the characteristics of data used in the Internet service is that data is suddenly generated without notice. Furthermore, the amount of data generated is not constant and cannot be predicted. Therefore, when the terminal suddenly generates data to be transmitted to the base station, the base station allocates an appropriate amount of radio resources to the terminal if there is a PHR previously received from the terminal by the base station. Is easy. Here, the PHR itself is not transmitted to the base station in a reliable manner. That is, not all the PHRs transmitted by the terminal can be normally received by the base station. Therefore, in the prior art, periodic PHR transmission is used. In particular, the terminal operates a timer (ie, a periodic PHR timer) and transmits a PHR to the base station every time the timer expires.

  In the prior art, the terminal triggers a periodic PHR when the periodic timer expires. When the period PHR is actually transmitted, the period timer is restarted. However, the PHR is also triggered when the path loss measured by the terminal changes more than a predetermined threshold.

  As described above, the terminal transmits a new PHR to the base station when the periodic timer expires. Then, the terminal periodically restarts the periodic timer. The terminal continuously monitors the path loss, and transmits a new PHR when the monitored path loss changes more than a threshold value.

  FIG. 5 is a diagram illustrating an example of transmission of a power headroom report (PHR) according to the prior art. As shown in FIG. 5, if the time point when a new PHR is transmitted due to a path loss change and the time point when a new PHR is transmitted due to the expiration of a periodic timer are very close, the path loss in this section will hardly change in practice. Therefore, the information included in the new PHR due to the expiration of the periodic timer is not significantly different from the information included in the new PHR due to the path loss change. This leads to waste of radio resources. That is, the conventional technique has a problem that radio resources are unnecessarily used during the PHR transmission process.

  Accordingly, it is an object of the present invention to provide an improved method for effectively transmitting a power headroom report from a terminal to a base station, and to prevent waste of radio resources in the prior art.

  In order to achieve the above and other advantages, and in accordance with the objectives of the present invention, provide power headroom reporting (PHR) in a wireless communication system as implemented and broadly described herein. And determining whether the power headroom report has been triggered and, if it is determined that at least one power headroom report has been triggered, an allocated uplink resource relates to the power headroom report. Determining whether a MAC control element can be accommodated, and transmitting the MAC control element based on a power headroom value if the allocated uplink resource is determined to be capable of accommodating the MAC control element. A method comprising the steps of:

The present invention also provides the following items, for example.
(Item 1)
A method for providing a power headroom report (PHR) in a wireless communication system, comprising:
Determining whether the power headroom report has been triggered;
If it is determined that at least one power headroom report has been triggered, determining whether the allocated uplink resources can accommodate a medium access control (MAC) control element (CE) for the power headroom report. When,
Transmitting the MAC control element based on a power headroom value when it is determined that the allocated uplink resource can accommodate the MAC control element. How to provide reports.
(Item 2)
The method of claim 1, wherein the MAC control element is included in a MAC protocol data unit (PDU).
(Item 3)
The method of claim 1, wherein the MAC control element is a PHR MAC control element.
(Item 4)
The power headroom report is triggered by at least one of path loss changes, period timer for PHR transmission (PHR transmission), and setting or resetting of PHR functionality. The method for providing a power headroom report according to item 1.
(Item 5)
The power headroom report providing method according to item 4, wherein the power headroom report is triggered when the path loss changes more than a threshold value.
(Item 6)
The power headroom report providing method according to item 4, wherein the power headroom report is triggered when the PHR transmission periodic timer expires.
(Item 7)
The method of claim 4, wherein the power headroom report is not triggered when the PHR functionality reconfiguration is used to disable the function.
(Item 8)
The method of claim 1, wherein the allocated uplink resource accommodates the MAC control element according to a result of logical channel prioritization.
(Item 9)
The method of claim 1, wherein the value of the power headroom is obtained from a physical layer.

The accompanying drawings, which are included to facilitate understanding of the invention and constitute a part of this specification, illustrate various embodiments of the invention, and together with the description of the specification, explain the principles of the invention. To do.
It is a figure which shows the network structure of E-UMTS which is a mobile communication system with which a prior art and this invention are applied. It is a figure which shows an example of the structure of the control plane of the radio | wireless interface protocol between UE and UTRAN based on the 3GPP radio | wireless access network standard by a prior art. It is a figure which shows an example of the structure of the user plane of the radio | wireless interface protocol between UE and E-UTRAN based on the 3GPP radio | wireless access network standard by a prior art. It is a figure which shows an example of operation | movement of dynamic radio | wireless resource allocation. It is a figure which shows an example of transmission of the electric power headroom report (PHR) by a prior art. FIG. 4 is a diagram illustrating an example of transmission of a power headroom report (PHR) according to the present invention.

  One aspect of the present invention relates to the inventors' knowledge about the problems of the prior art described above and below. Based on this finding, the features of the present invention were obtained.

  Although the present invention has been disclosed to be realized in a mobile communication system such as UMTS developed in conformity with the 3GPP standard, the present invention can also be applied to other communication systems that operate in conformity with other standards. .

  Hereinafter, the structure and operation of a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

  Generally, in order to prevent waste of radio resources, the base station has to know the power headroom report (PHR) of the terminal, and therefore allocates radio resources to the terminal. The power headroom reporting process according to the present invention will be described as follows. First, the power headroom reporting process is triggered when: 1) When the path loss changes more than the threshold after transmission of PHR, 2) When the periodic PHR timer expires, or 3) When the periodic PHR process or PHR function is set or reset.

  If a power headroom report is triggered due to one of the conditions, the terminal checks whether there is a newly allocated uplink resource during the current transmission time interval (TTI). If there is the uplink resource, the power headroom value is received from the physical layer. Thereafter, it instructs the Multiplexing and Assembly (MA) entity to generate a PHR MAC control element (CE) based on the power headroom value. In this process, if the PHR is a periodic PHR, the periodic PHR timer is restarted.

  Generally, the medium access control (MAC) layer is composed of a plurality of entities, and each entity performs a specified function. Among these is the Multiplexing and Assembly (MA) entity. The MA entity determines how to use which radio resources allocated from the base station are used for transmission of data. Also, the MA entity generates or configures a MAC PDU based on the MA entity. For example, if a radio resource capable of transmitting 200 bits is allocated to a terminal, and there is data that can transmit 150 bits in the first logical channel and data that can transmit 150 bits in the second logical channel, the MA entity may It is determined how much data is used to construct a MAC PDU from each logical channel, and a MAC PDU is generated based on this determination. In general, even if radio resources are allocated, not all data stored in each logical channel or all MAC CE (control element) generated by a MAC entity can be transmitted at all times. That is, when PHR is triggered, even if radio resources are allocated to the MAC entity, the PHR is not always transmitted by the allocated radio resources. In other words, if the MA entity decides to transmit data in preference to PHR MAC CE, the MAC PDU will no longer contain PHR. In this case, since the base station cannot receive the PHR from the terminal, radio resources are not appropriately allocated.

  As described above, the present invention seeks to provide a method for effectively transmitting a power headroom report (PHR) from a terminal to a base station.

  FIG. 6 is a diagram illustrating an example of transmission of a power headroom report (PHR) according to the present invention.

  As shown in FIG. 6, according to the present invention, the terminal restarts the periodic PHR timer every time it transmits PHR (or periodic PHR) to the base station. In addition, when the PHR is transmitted due to a change in the path loss value, the terminal restarts the period timer. In FIG. 6, according to the prior art, the periodic PHR timer expires at time B, and the PHR is transmitted to the base station at time B. However, when the PHR is transmitted due to a path loss change, the periodic PHR timer is restarted, so that the PHR does not need to be transmitted to the base station at the time B, and the time C at which the restarted periodic timer expires. The PHR is transmitted to the base station. Therefore, the number of unnecessary PHR transmissions is minimized in the present invention.

  Accordingly, the first embodiment of the power headroom reporting process according to the present invention will be described as follows. First, the power headroom reporting process is triggered by the following conditions: 1) When the path loss changes more than the threshold after transmission of PHR, 2) When the periodic PHR timer expires, or 3) When the periodic PHR process or PHR function is set or reset.

  If a power headroom report is triggered by one of the conditions, the terminal checks whether there are newly allocated uplink resources during the current transmission time interval. If there is the uplink resource, the power headroom value is received from the physical layer. Thereafter, it instructs the Multiplexing and Assembly (MA) entity to generate a PHR MAC control element (CE) based on the power headroom value. In this process, if the PHR is a periodic PHR, the periodic PHR timer is restarted.

In addition, the present invention proposes that the PHR process is performed based on a determination of a Multiplexing and Assembly (MA) entity. In particular, the MA entity determines whether a new MAC PDU can accommodate a PHR MAC control element (or MAC PHR CE). New MAC PDU is PHR MAC
If it is determined that the CE cannot be accommodated, the PHR process is not triggered. In this case, the PHR MAC CE is not included in the new MAC PDU. On the other hand, if a new MAC PDU can accommodate the PHR MAC CE, the PHR process is triggered and the PHR is transmitted according to further conditions. In this case, the periodic PHR timer is restarted, the PHR MAC CE is included in the new MAC PDU, and the new MAC PDU is transmitted.

  Also, when a new uplink resource is allocated, the MA entity determines which logical channel data or which MAC CE can be transmitted by the new uplink resource. As a result, if the MAC PDU can accommodate the MAC PHR CE, the MA entity notifies it to the PHR process. Based on the notification, the PHR process determines whether to trigger the PHR in consideration of a path loss change or a periodic PHR timer. When the PHR is triggered, it instructs the MA entity to include the PHR in the MAC PDU. That is, if there is a triggered MAC PHR CE and a newly allocated resource, and the new radio resource can accommodate the MAC PHR CE, the MAC PHR CE is included in the MAC PDU and the MAC PDU is transmitted.

  Accordingly, a second embodiment of the power headroom reporting process according to the present invention will be described as follows. First, the power headroom reporting process is triggered by the following conditions: 1) When the path loss changes more than the threshold after transmission of PHR, 2) When the periodic PHR timer expires, or 3) When the periodic PHR process or PHR function is set or reset.

  If a power headroom report is triggered due to one of the above conditions, check if there is a new PHR transmission after the most recent PHR transmission. Thereafter, if there is a new PHR transmission, the terminal checks whether there is a newly allocated radio resource. If there is a newly allocated radio resource, the terminal may determine that the MAC PDU transmitted by the newly allocated uplink resource is a PHR MAC as a result of prioritization (eg, logical channel prioritization). It is determined whether the CE can be accommodated. If the newly allocated radio resource can accommodate the PHR MAC CE, the terminal receives a power headroom value from the physical layer. Thereafter, it instructs a Multiplexing and Assembly (MA) entity to generate a PHR MAC control element based on the power headroom value. Then, the period PHR timer is restarted, and then all PHRs are canceled.

  Furthermore, the present invention proposes to consider the type of PHR setting during the power headroom reporting process. In particular, when the setting for the PHR process is changed, it is determined whether to trigger the PHR according to the type of the PHR setting. Specifically, when the PHR setting is changed by an upper layer (for example, RRC layer), the present invention proposes to determine whether the change of the PHR setting indicates the end of the PHR process. Thereafter, if the change in the PHR setting indicates the end of the PHR process, the PHR is not triggered. On the other hand, if the change in the PHR setting does not indicate the end of the PHR process, the PHR can be triggered.

  Accordingly, a third embodiment of the power headroom reporting process according to the present invention will be described as follows. First, the power headroom reporting process is triggered by the following conditions: 1) When the path loss changes more than the threshold after transmission of PHR, 2) When the periodic PHR timer expires, 3) When the PHR function is set, or 4) The PHR function is reset, and this PHR resetting This is a case where the PHR function is not possible without being used.

  If a power headroom report is triggered due to one of the above conditions, check if there is a new PHR transmission after the most recent PHR transmission. Thereafter, if there is a new PHR transmission, the terminal checks whether there is a newly allocated radio resource. If there is a newly allocated radio resource, the terminal accommodates the PHR MAC CE as a result of prioritization (eg, prioritization of logical channels) by the MAC PDU transmitted by the newly allocated uplink resource. Determine if you can. If the newly allocated radio resource can accommodate the PHR MAC CE, the terminal receives a power headroom value from the physical layer. Thereafter, it instructs a Multiplexing and Assembly (MA) entity to generate a PHR MAC control element based on the power headroom value. Then, the period PHR timer is restarted, and then all PHRs are canceled.

Here, the PHR MAC CE referred to in the present invention is a MAC having an LCID.
It is a fixed size identified by the PDU subheader, and is composed of one octet.

  Also, as described above, the power headroom reporting (PHR) process provides the serving eNB with information regarding the difference between the nominal maximum UE transmission power and the estimated uplink (ie, UL-SCH) transmission power. used. The RRC configures two timers, a periodic PHR timer and a prohibit PHR timer, to signal the path loss (ie, dl-PathlossChange) that sets the measured downlink path loss change to trigger the PHR. To control power headroom reporting.

  According to the present invention, the text of the procedure is as follows:

A power headroom report (PHR) is triggered when one of the following events occurs:
If the UE has uplink resources for new transmissions, if the forbidden PHR timer expires after transmission of the PHR, or expires and the path loss changes more than dl-PathlossChange dB,
・ When the periodic PHR timer expires,
• PHR functionality is set or reset by the upper layer, which is not used and the function is not possible.
If the UE has UL resources allocated for new transmissions during the transmission time interval, the PHR process determines whether at least one PHR was triggered or the PHR was triggered for the first time after the last transmission of the PHR The PUL MAC control element can be accommodated by the allocated UL resource as a result of logical channel prioritization;
-Obtain the power headroom value from the physical layer,
Instructing the Multiplexing and Assembly process to generate and transmit a PHR MAC control element based on the value reported by the physical layer,
・ Start or restart the periodic PHR timer,
・ Start or restart prohibited PHR timer,
Cancel all triggered PHRs.

  The present invention is a method for providing a power headroom report (PHR) in a wireless communication system, comprising determining whether the power headroom report has been triggered, and determining that at least one power headroom report has been triggered. Determining whether the allocated uplink resource can accommodate a medium access control (MAC) control element for the power headroom report; and the allocated uplink resource can accommodate the MAC control element. Determining that the MAC control element is included in a MAC protocol data unit (PDU), and the MAC control element is a PHR MAC The power headroom report is a path loss change, Triggered by at least one of HR transmission periodic timer and PHR functionality setting or reconfiguration, when the path loss changes more than a threshold, the power headroom report is triggered and the PHR transmission periodic timer expires When the power headroom report is triggered and the reconfiguration of the PHR functionality is used to disable the function, the power headroom report is not triggered and the allocated uplink resources According to the result of logical channel prioritization, the MAC control element is accommodated, and the power headroom value is obtained from the physical layer.

  Although the present invention has been described in the context of mobile communications, it can be used in any wireless communication system that uses mobile devices such as PDAs and laptop computers with wireless communication characteristics (eg, interfaces). Also, the use of specific terms to describe the invention is not intended to limit the scope of the invention to a particular type of wireless communication system. The present invention applies to other wireless communication systems using various air interfaces and / or physical layers such as TDMA, CDMA, FDMA, WCDMA, OFDM, EV-DO, Wi-Max, Wi-Bro, etc. Can do.

  Embodiments of the invention are implemented as a method, apparatus, or article of manufacture that uses standard programming and / or engineering techniques to produce software, firmware, hardware, or combinations thereof. The term “product” refers to hardware logic (eg, an integrated circuit chip, Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), etc.), computer readable media (eg, hard disk drive, floppy (registered trademark)). Magnetic recording media such as disks and tapes), optical storage devices (CD-ROM, optical disks, etc.), volatile and non-volatile memory devices (eg EEPROM, ROM, PROM, RAM, DRAM, SRAM, firmware, program logic, etc.) Used to refer to code or logic executed in

  Code in the computer readable medium is accessed and executed by a processor. The code for realizing the embodiment of the present invention can be connected via a transmission medium or from a file server on a network. In that case, the product in which the code is realized includes a transmission medium such as a network transmission line, a wireless transmission medium, a signal propagating in space, a radio wave, and an infrared signal. Of course, those skilled in the art will understand that various modifications are possible without departing from the spirit of the present invention, and that the product includes a known information transmission medium. Let's go.

  The present invention can be realized in various forms as long as it does not depart from the concept and important characteristics of the present invention, and is not limited by the above-described embodiments. It should be construed broadly within the scope of the claims, and all modifications and variations that come within the scope of the claims of the present invention and equivalents of the claims are embraced within the scope of the claims of the present invention.

Claims (14)

  A method for providing power headroom reporting (PHR) by a user equipment (UE) in a wireless communication system comprising:
  The method
  Determining whether the PHR has been triggered, the PHR being triggered by setting or reconfiguring the PHR functionality, which is not used to disable PHR functionality;
  Determining whether the UE has uplink resources allocated for new transmissions;
  Determining whether the allocated uplink resource accommodates a PHR medium access control (MAC) control element, wherein the allocated uplink resource depends on a result of prioritization of logical channels. Accommodating control elements,
  It is determined that the PHR has been triggered, it is determined that the UE has uplink resources allocated for new transmissions, and it is determined that the allocated uplink resources accommodate the PHR MAC control element Generating and transmitting the PHR MAC control element based on a power headroom value obtained from the physical layer;
  Starting a periodic PHR timer after transmitting the PHR MAC control element;
  Including a method.   The method of claim 1, wherein the PHR is triggered by at least one of a PHR transmission periodic timer, a path loss change, and a periodic PHR setting or resetting.   The method of claim 2, wherein the PHR is triggered when the path loss changes greater than a threshold.   The method of claim 2, wherein the PHR is triggered when the PHR transmission periodic timer expires.   The method of claim 1, wherein the PHR MAC control element is included in a MAC protocol data unit (PDU).   The method of claim 1, wherein the power headroom report is not triggered when the reconfiguration of the PHR functionality is used to disable a function.   The method of claim 1, further comprising starting a forbidden PHR timer after transmitting the PHR MAC control element.   A user equipment (UE) configured to provide power headroom reporting (PHR) in a wireless communication system, comprising:
  The UE
  Memory,
  A processor operably coupled to the memory;
  With
  The processor is
  Determining whether the PHR has been triggered, the PHR being triggered by setting or reconfiguring the PHR functionality, which is not used to disable PHR functionality;
  Determining whether the UE has uplink resources allocated for new transmissions;
  Determining whether the allocated uplink resource accommodates a PHR medium access control (MAC) control element, wherein the allocated uplink resource depends on a result of prioritization of logical channels. Accommodating control elements,
  It is determined that the PHR has been triggered, it is determined that the UE has uplink resources allocated for new transmissions, and it is determined that the allocated uplink resources accommodate the PHR MAC control element Generating and transmitting the PHR MAC control element based on a power headroom value obtained from the physical layer;
  Starting a periodic PHR timer after transmitting the PHR MAC control element;
  A user equipment configured to perform.   The user equipment according to claim 8, wherein the PHR is triggered by at least one of a PHR transmission periodic timer, a path loss change, and a periodic PHR setting or resetting.   The user equipment according to claim 9, wherein the PHR is triggered when the path loss changes more than a threshold.   The user equipment according to claim 9, wherein the PHR is triggered when the PHR transmission periodic timer expires.   The user equipment according to claim 8, wherein the PHR MAC control element is included in a MAC protocol data unit (PDU).   The user equipment of claim 8, wherein the power headroom report is not triggered when the reconfiguration of the PHR functionality is used to disable a function.   9. The user equipment of claim 8, wherein the processor is further configured to start a forbidden PHR timer after transmitting the PHR MAC control element.