PATENT DOCUMENT

Publication Number: US-11115936-B2
Application Number: US-201916423425-A
Country: US
Kind Code: B2

Title: Apparatus and methods for communication resource allocation

Abstract:
Methods and corresponding systems for determining a transmit power in a mobile device include receiving, in the mobile device, a cell-wide power control parameter related to a target receive power at a serving base station. Thereafter, a transmit power is calculated in response to the cell-wide power control parameter and an implicit mobile-specific power control parameter. The mobile device then transmits using the transmit power. The cell-wide power control parameter can be a cell target signal to interference-plus-noise ratio, or a fractional power control exponent. The implicit mobile-specific power control parameter can be a modulation and coding level previously used by the mobile device, or a downlink SINR level measured by the mobile device.

Claims:
What is claimed is: 
     
       1. A method for performing a wireless communication service request in a wireless device, the method comprising:
 determining whether a resource utilization limitation exceeds a reporting threshold; 
 transmitting a service request message to a base station, wherein the service request message includes a power headroom of the wireless device in response to the wireless device determining that the resource utilization limitation exceeds the reporting threshold; and 
 receiving an uplink resource allocation grant from the base station, wherein the resource allocation is based at least in part on the service request message. 
 
     
     
       2. The method of  claim 1 , wherein the power headroom is a difference between a power level the wireless device is instructed to use and a maximum power level attainable by the wireless device. 
     
     
       3. The method of  claim 1 , wherein the service request message includes a size of data to be transmitted. 
     
     
       4. The method of  claim 1 , wherein the resource utilization limitation is based on a power limitation. 
     
     
       5. The method of  claim 1 , wherein the resource utilization limitation is based on a maximum number of resource blocks that can be used by the wireless device in an uplink transmission. 
     
     
       6. The method of  claim 1 , wherein the resource utilization limitation is one or more of:
 an amount of remaining power that can be used for uplink transmission, 
 a limit to the number of resource blocks that can be used during an uplink transmission based on the power headroom, and 
 a resource limit that depends upon the wireless device transmit power. 
 
     
     
       7. The method of  claim 1 , wherein the wireless device determines the resource utilization limitation after receiving a random access channel response, wherein the resource utilization limitation is based at least in part on instructions in the random access channel response;
 where the wireless device receives the random access channel response in response to transmitting a random access channel. 
 
     
     
       8. The method of  claim 7 , wherein the random access channel response includes instructions to adjust transmission timing and power control. 
     
     
       9. A wireless communication device comprising:
 a processor configured to determine whether a resource utilization limitation exceeds a reporting threshold; 
 a transmitter configured to transmit a service request message to a base station, wherein the service request message includes a power headroom of the wireless device in response to the processor determining that the resource utilization limitation exceeds the reporting threshold; and 
 a receiver configured to receive an uplink resource allocation grant from the base station, wherein the resource allocation is based at least in part on the service request message. 
 
     
     
       10. The wireless communication device of  claim 9 , wherein the power headroom is a difference between a power level the wireless device is instructed to use and a maximum power level attainable by the wireless device. 
     
     
       11. The wireless communication device of  claim 9 , wherein the service request message includes a size of data to be transmitted. 
     
     
       12. The wireless communication device of  claim 9 , wherein the resource utilization limitation is based on a power limitation. 
     
     
       13. The wireless communication device of  claim 9 , wherein the resource utilization limitation is based on a maximum number of resource blocks that can be used by the wireless device in an uplink transmission. 
     
     
       14. The wireless communication device of  claim 9 , wherein the resource utilization limitation is one or more of:
 an amount of remaining power that can be used for uplink transmission, 
 a limit to the number of resource blocks that can be used during an uplink transmission based on the power headroom, and 
 a resource limit that depends upon the wireless device transmit power. 
 
     
     
       15. The wireless communication device of  claim 9 ,
 wherein the receiver is further configured to receive a random access channel response in response to the transmitter transmitting a random access channel; and 
 wherein the processor is further configured to determine the resource utilization limitation after the receiver receives the random access channel response, wherein the resource utilization limitation is based at least in part on instructions in the random access channel response. 
 
     
     
       16. The wireless communication device of  claim 15 , wherein the random access channel response includes instructions to adjust transmission timing and power control. 
     
     
       17. An apparatus comprising:
 a memory storing software instructions; and 
 a processor configured to implement the software instructions to cause a wireless device to:
 determine whether a resource utilization limitation exceeds a reporting threshold; 
 transmit a service request message to a base station, wherein the service request message includes a power headroom of the wireless device in response to the apparatus determining that the resource utilization limitation exceeds the reporting threshold; and 
 receive an uplink resource allocation grant from the base station, wherein the resource allocation is based at least in part on the service request message. 
 
 
     
     
       18. The apparatus of  claim 17 , wherein the resource utilization limitation is one or more of:
 an amount of remaining power that can be used for uplink transmission, 
 a limit to the number of resource blocks that can be used during an uplink transmission based on the power headroom, and 
 a resource limit that depends upon the wireless device transmit power. 
 
     
     
       19. The apparatus of  claim 17 , wherein the processor is further configured to implement the software instructions to cause the wireless device to determine the resource utilization limitation after receiving a random access channel response, wherein the resource utilization limitation is based at least in part on instructions in the random access channel response;
 where the wireless device receives the random access channel response in response to transmitting a random access channel. 
 
     
     
       20. The apparatus of  claim 19 , wherein the random access channel response includes instructions to adjust transmission timing and power control.

Description:
PRIORITY CLAIM 
     This application is a continuation of and claims the benefit of priority from U.S. patent application Ser. No. 13/944,137, entitled “Resource Allocation in a Communication System”, filed on Jul. 17, 2013, which is a continuation of and claims the benefit of priority from U.S. patent application Ser. No. 11/725,423, entitled “Resource Allocation in a Communication System” filed on Mar. 19, 2007 (now U.S. Pat. No. 9,295,003), which are fully incorporated herein by reference for all purposes. 
     The claims in the instant application are different than those of the parent application or other related applications. The Applicant therefore rescinds any disclaimer of claim scope made in the parent application or any predecessor application in relation to the instant application. The Examiner is therefore advised that any such previous disclaimer, and the cited references that it was made to avoid, may need to be revisited. Further, any disclaimer made in the instant application should not be read into or against the parent application or other related applications. 
    
    
     BACKGROUND 
     Field of the Application 
     This disclosure relates generally to communication systems and equipment, and more specifically to techniques and apparatus for allocating communication system resources to mobile devices in the communication system. 
     Background of the Disclosure 
     Many wireless communication systems use base stations to communicate with one or more mobile devices (i.e., user equipment or “UE”) within a cell served by the base station. Data sent from the base station to the user equipment is transmitted through a wireless channel referred to as a downlink channel, and data transmitted from the user equipment to the base station is transmitted through a wireless channel referred to as an uplink channel. 
     The wireless communication system has limited resources that can be allocated to the mobile devices and normally attempts to do the allocation in order to maximize the use of the bandwidth available in the uplink and downlink channels. For example, a frequency, or set of frequencies, is a resource that can be allocated to the mobile device to use for wireless transmission or reception. A time for transmission, or a transmission “time slot,” is also a resource that can be allocated to the mobile device to use for wireless transmission or reception. 
     With regard to transmitting on the uplink channel, transmit power is a resource that can be allocated to the mobile device to use for wireless transmission. The proper allocation of transmit power is needed so that the base station receives relatively even power levels across the spectrum used by the mobile devices. Proper transmit power allocation also helps to avoid interference with transmissions from other mobile devices, whether those other mobile devices are in the same cell or an adjacent cell. 
     Power received at the base station can be affected by the distance between the mobile device and the base station, and other types of pathloss between the mobile and base. Distance-dependent path loss reduces the power of the receive signal because of the distance the signal travels. In addition, power can be reduced through shadowing, which occurs when an object comes between the mobile device and base station. For example, if a person with a mobile device walks down a street and a building comes between the mobile device and that base station, pathloss increases due to shadowing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example and is not limited by the accompanying figures, in which like references indicate similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. 
         FIG. 1  is a high-level block diagram of a wireless communication system in accordance with one or more embodiments; 
         FIG. 2  is a high-level bounce diagram depicting messages sent between various components of wireless communication system of  FIG. 1  in accordance with one or more embodiments; 
         FIG. 3  is a representation of a message format in accordance with one or more embodiments; 
         FIG. 4  is a high-level bounce diagram depicting messages sent between various components of wireless communication system of  FIG. 1  in accordance with one or more embodiments; 
         FIG. 5  is a high-level flowchart depicting a process that can be executed by a mobile device in accordance with one or more embodiments; and 
         FIG. 6  is a high-level flowchart depicting a process that can be executed by a mobile device in accordance with one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a high-level diagram of portions of a communication system  100  in accordance with one or more embodiments. Communication system  100  can be a wireless communication system or other similar communication system that uses power control techniques and algorithms to control a transmit power of one or more devices transmitting data. As illustrated,  FIG. 1  includes base stations  102  and  104  and mobile devices  106  and  108 , which mobile devices can also be referred to as mobile stations, subscriber units, mobile terminals, or user equipment (UE). Base station  102  generally communicates wirelessly with mobile devices in cell  110 , while base station  104  generally communicates wirelessly with mobile devices in cell  112 . Base station controller  114  (which in some embodiments can be referred to as an eNode-B or an evolved node-B) is coupled to base station  102 , and perhaps other base stations  116 , in order to control the operation of base station  102  and other base stations. In various embodiments, base station controller  114  can perform packet scheduling functions, connection mobility control, load balancing, inter Radio-Access-Technology handover, and the like. Similarly, base station controller  118  is coupled to base station  104 , and perhaps other base stations  120 , for the purpose of controlling base station  104 . The base station controllers can be coupled to base stations via a communication link that can be wireless, wireline, fiber optic, or the like. In some embodiments, the base station controller can be co-located with a base station. 
     In one embodiment, communications system  100  can be implemented according to the specification for the long-term evolution (LTE) project within the Third Generation Partnership Project (3GPP) wireless system, which is essentially a wireless packet data system that can transmit voice (e.g., VoIP) and other data. 
     Mobile device  106  can communicate with base station  102  via wireless communication link  122 . Mobile device  108  can communicate with base station  104  via wireless communication link  124 . When mobile device  106  is near the edge of its serving cell  110 , and also near another mobile device  108 , which is near the edge of its serving cell  112 , interference  126  from mobile device  108  can interfere with transmissions from mobile device  106  in wireless communications link  122 , particularly when mobile device  106  and mobile device  108  have been assigned the same transmission frequency. 
     In each cell  110  and  112 , the base station (e.g., base stations  102  and  104 ) can simultaneously receive uplink transmissions from a plurality of mobile devices, such as mobile device  106  and others not shown. In some embodiments, the base station is adapted to receive the wireless uplink transmissions with receive signal strengths that are substantially the same. To make the receive signal strengths substantially the same, an uplink transmit power control algorithm can be used to control the transmit power of each mobile device. In one embodiment, the base station can broadcast a cell-wide power control parameter to all mobile devices in the cell served by the base station. For example, in one embodiment, base station  102  can broadcast, to all mobile devices (e.g., mobile device  106 ) served by base station  102 , a cell-wide target for received power (i.e., a power control parameter) that is related to the signal to interference-plus-noise ratio (SINR) received at the base station. 
     In another embodiment, the cell-wide power control parameter can be a fractional power control exponent. The fractional power control exponent can be represented as the symbol “a” in Equation 1, below:
 
mobile_station_power i   =P max×min(1,max( R   min ,( PL   i   /PL   xile ) α )  Eqn. 1
 
where mobile_station_power i  is the power calculated by the ith mobile in the cell, PL xile  is the x-percentile of the path-loss from all mobiles in the cell to the base station, R min  is the minimum power reduction ratio, and PL i  is the path loss from the mobile device (or UE) in question to the base station. Using equation 1 above, with 0&lt;α&lt;1, mobile devices at the center of the cell have lower thresholds than those at the edges of the cell, resulting in less interference in the network.
 
     Referring now to  FIG. 2 , there is depicted a “bounce diagram” illustrating messages communicated between various components of communication system  100 . As depicted, messages are communicated between mobile device  202 , serving base station  204 , and base station controller  206 . Base station controller  206  can be implemented with base station controller  114 , as shown in  FIG. 1 . Although base station  204  and base station controller  206  are shown separately, they may or may not be physically co-located, depending upon the system. 
     Before a mobile device has been synchronized (e.g., when the mobile device is in the idle mode), the mobile device can initiate communication with the serving base station by sending an asynchronous RACH  208  (i.e., an asynchronous random access channel message). The random access channel is typically shared by all mobile devices in a cell served by the base station. Asynchronous RACH  208  preamble can tell base station  204  that mobile device  202  has a message for the base station. A request for service on the random access channel can be referred to as a “RACH request.” 
     Asynchronous RACH  208  is initially transmitted at a relatively low power to avoid excessive interference. Therefore, asynchronous RACH  208  may not be received by base station  204 . If asynchronous RACH  208  is not received by base station  204 , there will be no response by base station  204 , and mobile device  202  will resend asynchronous RACH  210  at an incrementally higher power level so that the asynchronous RACH is eventually received by base station  204 , 
     Upon reception of asynchronous RACH  210 , base station  204  can respond by sending RACH response  212 . RACH response  212  can include a message from base station  204  that acknowledges mobile device  202  and further instructs mobile device  202  with regard to signal timing, transmit power, and a time and frequency to use for a next uplink transmission. As an example, RACH response  212  can contain instructions to mobile device  202  to adjust the timing of its transmission by +1.04 μS, to adjust transmit power by −2 dB, and to send a synch RACH (i.e., a synchronous RACH message) at a particular start frequency, with a particular number of frequencies, and within a particular time interval. 
     After receiving RACH response  212 , mobile device  202  can respond with a synch RACH message  214  that indicates that the mobile device is requesting a service from the base station. Additionally, mobile device  202  can use a part or segment of the message to indicate that it has a resource utilization limitation, if such a resource utilization limitation exceeds a limitation threshold for reporting to the base station. 
     In one embodiment, the mobile device resource utilization limitation can be a limit to the number of resource blocks that can be used during an uplink transmission relative to a current power level and current modulation and encoding scheme (MCS). In another embodiment, the mobile device resource utilization limitation can be an amount of remaining power (e.g., a power headroom) that can be used for uplink transmission. Thus, in one embodiment, synch RACH message  214  can indicate that the mobile device has a file to be transferred (i.e., requesting file transfer services), and that the mobile device is power limited to 4 resource blocks (i.e., the mobile device resource utilization limitation indicates that the mobile device should not be assigned more than 4 resource blocks, taking into consideration the current transmit power, the maximum transmit power of the mobile device, and the current modulation and coding scheme). 
     Note that the resource utilization limitation must exceed a limitation threshold before the limit is reported to the base station. This limitation threshold for reporting should be set at a point where device resource utilization limitations are reported when there is a likelihood that an uplink scheduler will schedule an uplink transmission that exceeds the capacity of the mobile device. When the mobile device sends a mobile device resource utilization limitation message, the base station (or other uplink traffic scheduling entity) can use this information to intelligently schedule uplink traffic in a way that does not exceed the transmit power capabilities of the mobile device. For example, if base station  204  decides to allocate a number of resource blocks greater than the number of blocks that the mobile device has indicated as a limit, the base station can scale back the modulation and coding scheme so that the mobile device can transmit a requested power on all the assigned resource blocks. 
     With regard to the format of the synch RACH message  214 ,  FIG. 3  shows an example of one embodiment of the format of the message. As illustrated, message  300  can include header  302 , a service request  304 , a service request parameter  306 , an optional mobile device resource utilization limitation  308 , and an error control field  310 . Header  300  can be used to indicate the type of message. Service request  304  can be a field for indicating a request for a service from the base station serving the mobile device. Such a request for service can include a request to transfer a file, a request to place a voice call, a request for email delivery, a request for downloading music or video clips, or the like. Service request parameter  306  can contain information related to the service request, such as a file size for the file transfer, or other similar information needed to complete the service request. 
     If the threshold for reporting the mobile device utilization limitation has been exceeded, the mobile device resource utilization limitation  308  portion of synch RACH message  214  can include a power limited flag  312  that indicates whether it is possible for the mobile device to be scheduled for an uplink communication in a manner that exceeds its power capability. For example, if the flag is set it can indicate that the mobile device is currently operating at a power that is close to its maximum power, which implies that the base station could schedule an uplink transmission for the mobile device that would exceed its power transmission capacity. If the current power of a transmission is 21 dB, and the maximum power transmission is 24 dB, there is a chance that the base station would schedule the mobile device for uplink transmission using four resource blocks, which would require an additional 6 dB of power when only 3 dB of additional power is available before the mobile device reaches maximum power. In this case where base station  204  would like to schedule 4 resource blocks for mobile device  202 , base station  204  can either limit the maximum number of resource blocks to 2, or base station  204  can schedule 4 resource blocks and assume that mobile device  202  will scale the transmit power by 2 (i.e., reduce the power by ½) and use all 4 resource blocks. Note that base station  204  can schedule a number of resource blocks exceeding the number of resource blocks reported in the mobile device resource utilization limitation  308 , because the mobile device can be a better candidate for scheduling than other mobile devices. 
     In addition to the power limited flag  312 , mobile device resource utilization limitation field  308  can include a field to indicate resource block capacity  314 . Resource block capacity field  314  can indicate a maximum number of resource blocks the mobile device can use, or the field can indicate a number of additional blocks that can be used by the mobile device. Present transmit power field  316  can be used to indicate the present transmit power of the mobile device. If mobile device sends the present transmit power to the base station, the base station can calculate the maximum number of resource blocks that can be used by the mobile device, or the number of additional blocks that can be used by the mobile device. Embodiments of mobile device resource limit field  308  can include power limited flag  312  and either resource block capacity  314  or present transmit power  316 , or both. 
     Mobile device resource utilization limitation field  308  can also indicate other limitations of the mobile device. For example, many mobile devices can transmit using one of many different levels of modulation and coding schemes (MCS). If a mobile device does not have all the levels, or if some levels are unavailable because of low battery (or other similarly limiting condition), or because the mobile device is not a full-featured device that implements all the MCS levels, then mobile device resource utilization limitation field  308  can inform the scheduler of these limitations so that a mobile device is not scheduled to perform an uplink transmission that it cannot accomplish. 
     In  FIG. 2 , after the mobile device sends synch RACH message  214  to serving base station  204 , the message is forwarded to base station controller  206  as shown at  216 . Base station controller  206  can respond with downlink control message  218  sent to serving base station  204 , and forwarded to mobile device  202  as shown at  220 , wherein the downlink control message instructs mobile device  202  to sound out the channel at a particular time and frequency. Mobile device  202  can respond by sending an unlink channel sounding message  222 , where the mobile device transmits known codes or data (e.g., a known data sequence) on a set of subcarriers which are more or less evenly distributed across the channel bandwidth. In some embodiments, the known codes can be pilot sequences embedded in the uplink data channel. Channel sounding is a process for characterizing a channel between the base station and the mobile device. The channel can be characterized by calculating the channel impulse response. 
     After uplink channel sounding message  222  has been received by base station  204 , base station  204  prepares a carrier to interference-plus-noise ratio (CINR) and power control (PC) report  224 , which is then forwarded to base station controller  206 . CINR is a measurement of signal effectiveness, expressed in decibels (dBs). The carrier is the desired signal, and the interference can include noise, co-channel interference, or other channel interference, or all of these. In order for the signal receiver to decode the signal, the signal must fall into an acceptable CINR range. Co-channel interference is more of a problem when frequencies are reused at short distances. In embodiments where channel sounding is not used in the system, base station  204  can infer the CINR from long term tracking of the channel through the reference symbols of the data channel. 
     After receiving any mobile device resource utilization limitation, and any mobile-specific power control parameters, such as the data resulting from a channel sounding, base station controller  206  can prepare and send to base station  204  a grant for a resource allocation  226 . Grant for resource allocation  226  is then forwarded to mobile device  202  as shown at  228 . 
     The grant for resource allocation  226  can either be a grant for a dynamic resource allocation or a grant for a persistent resource allocation. A grant for a dynamic resource allocation is a relatively short term grant that includes a one-time power control instruction for use during the duration of the dynamic resource allocation grant. A grant for a persistent resource allocation is a longer term grant that includes a power control instruction for initial use during the dynamic resource allocation grant, and subsequent power control instructions received periodically during the duration of the persistent resource allocation grant. 
       FIG. 4 . is a bounce diagram that depicts messages sent between mobile device  202 , serving base station  204 , and base station controller  206 , resulting in a grant of a persistent resource allocation in accordance with one or more embodiments. Messages and data communication  208  through  224  are similar to those discussed above with reference to  FIG. 2 . In this example, synch RACH  214  can include a request for a base station service that is best suited for a persistent resource allocation grant. For example, synch RACH  214  can include a request for a voice call. Persistent resource allocation grant  402  is sent from base station controller  206  to base station  204 , and then forwarded to mobile device  202  as shown at  404 . Persistent resource allocation grant  402  can contain a power control instruction for initial use during the persistent resource allocation grant. Subsequent power control instructions can be sent from base station controller  206 , to base station  204 , and to mobile device  202 . For example, after a period of time decrement power instruction  406  follows persistent resource allocation grant  402 . Decrement power instruction  406  is forwarded to mobile device  202  as shown at  408  to instruct mobile device  202  to reduce its power by a predetermined incremental amount. Following power control instruction  406  are additional periodic power control instructions  410  and  414 , which are forwarded to mobile device  202  has shown at  412  and  416 , respectively, for the duration of the persistent resource allocation grant. 
     Thus, following a dynamic resource allocation grant  226 , mobile device  202  operates in a mode wherein additional power control instructions are not expected from base station  204 . Following a persistent resource allocation grant  402 , mobile device  202  operates in a mode wherein additional power control instructions are expected from base station  204  for the duration of the persistent resource allocation. 
       FIG. 5  shows a high-level flowchart of processes that can be executed by mobile device  106  in  FIG. 1 , or other systems with appropriate functionality, in accordance with one more embodiments. As shown, the process begins at  502 , and thereafter continues at  504  wherein the process sends an asynchronous RACH to the base station. The asynchronous RACH message (such as asynchronous RACH message  208 ,  210  in  FIG. 2 .) can be sent from an idle mobile device (e.g. mobile device  106 ) to the base station (e.g. base station  102 ) to alert the base station that the mobile device has a message for the base station. 
     Next, the process receives a RACH response from the base station, as illustrated at  506 . The RACH response acknowledges the transmission from the mobile device, and can further instruct the mobile device to adjust its transmission timing and its transmit power, and to respond with a synchronous RACH at a particular time slot and on a particular frequency (e.g., a set of frequencies or resource block). 
     After receiving the RACH response, the mobile device determines a mobile device power limitation, as depicted at  508 . In one embodiment, this step can be implemented by determining the power headroom of the mobile device, wherein the power headroom is the difference between the power the mobile device was instructed to use in the RACH response and the maximum power of the mobile device. 
     Once the mobile device power limitation has been determined, the process determines a mobile device resource utilization limitation based on the power limitation, as illustrated at  510 . In one embodiment, this step can be implemented by determining a maximum number of resource blocks that can be used by the mobile device in an uplink transmission based on the power headroom. For example, in one embodiment, if the mobile device has currently been instructed to transmit at 21 dBm, and the maximum power for the mobile device is 24 dBm, which makes the power headroom 3 dB, and the maximum number of resource blocks that can be used by the mobile device would be 2, since adding a second resource block requires twice the power, which is an additional 3 dB increase in power. 
     Next, the process determines whether the mobile device resource utilization limitation exceeds a reporting threshold, as depicted at  512 . The reporting threshold can be set to a level that prevents mobile devices that are not limited by their power headroom from reporting the mobile device power limitation. Mobile devices that are not limited by their power headroom can save the bandwidth needed to report the resource utilization limitation because the scheduler in the base station (or base station controller) does not need to be concerned with limiting scheduled resources to a mobile device that is not limited by power headroom. Conversely, if a mobile device is limited by its power headroom, the scheduler needs to know, preferably in advance of scheduling, so that it will not schedule a resource allocation that will exceed the mobile device&#39;s transmit power capability. 
     If the resource utilization limitation exceeds the reporting threshold, the process passes to  514  wherein the process sends a synch RACH (such as sync RACH  214  shown in  FIG. 4 ) to the base station, where in the synch RACH includes a resource allocation request and the resource utilization limitation. The resource allocation request can include a request for a file transfer, a request for a voice call, a request for a video or music file, or the like. The resource utilization limitation can include a maximum number of resource blocks, a maximum level of modulation and coding, or other similar resource limits that depend upon the mobile device transmit power. Note that in another embodiment the resource utilization limitation parameter can be transmitted on a dedicated message, and does not have to be piggy-backed on the sync RACH message. 
     If the resource utilization limitation does not exceed the reporting threshold, the process passes to  516  wherein the mobile device sends a synch RACH to the base station that includes a resource allocation request, but no resource utilization limitation. 
     After the synch RACH message is sent to the base station, the process can receive a channel sounding command, as illustrated at  518 . In response to the channel sounding command, the process sends a channel sounding data sequence, as depicted  520 . The channel sounding data sequence is a known data sequence, which is transmitted at a known transmit power on preselected frequencies across the bandwidth of the communication system. Channel sounding gives the base station and/or the base station controller data that represents the quality of the channel on the various frequencies across the spectrum. This information is useful in scheduling uplink transmissions from the mobile devices because the scheduler prefers to grant resources to mobile devices that are presently capable of using those resources with desirable channel conditions. In embodiments where channel sounding is not used in the system, base station  204  can infer the CINR from long term tracking of the channel through the reference symbols of the data channel. 
     After sending the channel sounding sequence, the process receives a dynamic or a persistent resource allocation grant, and determines whether the grant was dynamic or persistent at  522 . If the grant was dynamic, the process receives instructions for a dynamic uplink transmission, including a power control instruction for use during the duration of the dynamic resource grant, as depicted at  524 . The process then transmits on the uplink according to the dynamic resource allocation grant as shown at  526 , and uses the power control instruction to set the transmit power for the duration of the grant. At the end of data transmission according to the dynamic resource allocation grant, the process ends as depicted at  536 . 
     Alternatively, if the grant was persistent, the process receives instructions for a persistent uplink transmission, including an initial power control instruction to begin the persistent resource grant transmission, as illustrated at  528 . The process then transmits on the uplink according to the persistent resource allocation grant, and uses the initial power control instruction to start the persistent grant transmission, as shown at  530 . After a period of time, the process receives an additional power control instruction, as depicted at  532 . 
     Next, the process determines whether the persistent grant has expired, as illustrated at  534 . If the persistent grant has not expired, the process continues to send more data at  530 , and periodically receives updated power control instructions at  532 . 
     If the persistent grant has expired, the process of transmitting on the allocated uplink resource according to the persistent resource grant ends, as shown at  536 . 
       FIG. 6  shows a high-level flowchart of processes that can be executed by mobile device  106  in  FIG. 1 , or other systems with appropriate functionality, in accordance with one or more embodiments. As illustrated, the process begins at  602 , and thereafter continues at  604  wherein the process receives a cell-wide power control parameter. The cell-wide power control parameter is a parameter that is sent to all mobile devices in the cell by the serving base station. The parameter can be sent by a broadcast channel. In one embodiment, the cell-wide power control parameter is a cell target signal to interference-plus-noise ratio (SINR) received at the base station (e.g., base station  102 ). In another embodiment, the cell-wide power control parameter can be a fractional power control exponent, which is shown as symbol “.a.” in Equation 1 above. 
     After receiving the cell-wide power control parameter, the process determines an implicit mobile-specific power control parameter that is related to a target receive power at a serving base station, as illustrated at  606 . An implicit mobile-specific power control parameter is a parameter related to uplink power control that is specific to the mobile device (i.e., a parameter that is not broadcast) and that is implied by other messages or commands sent to the mobile device, or measurements made by the mobile device, which makes the implicit parameter one that does not require additional message traffic from the base station. In one embodiment, the implicit mobile-specific power control parameter can be a modulation and coding level previously used by the mobile device. The modulation and coding level is sent to the mobile device by the base station, and it implicitly indicates the uplink channel characteristics between the mobile device and the base station. In one embodiment, the modulation and coding level previously used by the mobile device can be an average modulation and coding level averaged over a time window. 
     In another embodiment, the implicit mobile-specific power control parameter can be a downlink SINR level (or an averaged downlink SINR level) measured by the mobile device. In a time domain duplex (TDD) communication system, by the reciprocity principle, the downlink SINR implicitly indicates the uplink channel characteristics. In a frequency domain duplex (FDD) communication system, the uplink and downlink channel fast fading components may be uncorrelated even though the pathloss and shadowing components are identical. Averaging the downlink SINR over time and frequency will average out the fading components and provide a good implicit estimate of the uplink channel characteristics. 
     In some embodiments, the mobile device can also receive a mobile-specific power control parameter, in addition to the cell-wide power control parameter and the implicit mobile-specific power control parameter. The mobile-specific power control parameter can be received in a message from the base station that is directed specifically to the mobile device. In the case where the mobile device receives a cell-wide power control parameter and a mobile-specific powerful parameter, the implicit mobile-specific power control parameter can be a correlation between the mobile-specific power control parameter and a modulation and coding level assigned by the serving base station. Thus, the implicit mobile-specific power control parameter can vary between the case where the mobile-specific power control parameter correlates directly with the modulation and coding scheme and in the case where the mobile-specific power control parameter correlates in directly with the modulation and decoding scheme. As an example, a direct correlation between the power control parameter and the modulation and coding scheme is where the mobile device receives a relatively high power in combination with a relatively high modulation and coding level (i.e., a modulation and coding level that requires a higher power), and similarly the case where the mobile device receives a relatively low power in combination with a relatively low modulation and coding level. An example of an indirect correlation between the power control parameter and the modulation and coding scheme is where the mobile device receives a relatively high power in combination with a relatively low modulation and coding scheme, and vice versa. Thus, this implicit mobile-specific correlation factor varies between expected power levels and modulation and coding schemes, and unexpected combinations of power level and modulation and coding schemes. 
     Next, the process calculates the mobile device uplink transmit power using the cell-wide power control parameter and the implicit mobile-specific power control parameter, as depicted at  608 . In this step, the implicit mobile-specific power control parameter is used to adjust a transmitter power indicated by the cell-wide power control parameter, or to adjust a transmit power indicated by the cell-wide power control parameter in combination with a mobile-specific power control parameter. In one embodiment, this adjustment can be a percentage of the transmit power indicated by calculations using cell-wide parameters, or by calculations using cell-wide parameters in combination with mobile-specific parameters. 
     As an example, assume that the base station broadcasts a cell-wide target SINR that maps to an average MCS level of 16 QAM (i.e., 16 point constellation, quadrature amplitude modulation) (SINR 16 ) with coding rate 1/2. The mobile device will first calculate its transmit power to ensure that its signal is received at the base station with the cell-wide target SINR 16 . Then, the mobile device can autonomously calculate a correction factor based upon an implicit mobile-specific power control parameter, such as a history of uplink MCS allocated to the mobile device. If the mobile device observes that its average MCS level allocated over time and frequency is 4 QAM rate 1/2, which maps to an average SINR received at the base station of SINR 4 , a correction factor of SINR 16 -SINR 4  can be autonomously applied by the mobile device to bring it in line with the expected received SINR 16  at the base station. Thus, the difference between the target SINR and the implied SINR determines the addition (if the measured MCS implies a lower SINR at the base station) or subtraction (if the measured MCS implies a higher SINR at the base station) of an autonomous correction factor. 
     In one embodiment, the difference (i.e., the correction factor) can be applied directly to the transmit power at one time. In another embodiment the correction factor can be incrementally applied over a period, either by applying a number of fixed incremental corrections (e.g., change by 1 dB), or by applying a percentage of the correction factor over a fixed number of corrections (e.g., change by 20% of the correction factor over 5 changes). The correction factor can be periodically recalculated, even before a previous correction factor is completely applied. 
     Furthermore, the mobile device can make continuous measurements on the downlink SINR levels and average the measurements over time and frequency to estimate a long term downlink received SINR. This estimated long term SINR can then be compared to the uplink SINR the mobile device expects based on the autonomously corrected transmit power as calculated in the example above. A delta correction factor can be calculated and applied based on the difference, and the delta correction factor can then be used in the calculation of the autonomous correction factor to increase its accuracy. The delta correction factor can be used to compensate for inaccuracies in transmit power, which are due to a difference in a set transmit power and an actual transmit power in the mobile device. 
     After calculating the mobile device uplink transmit power, the mobile device transmits data using the transmit power, as illustrated at  610 . The data is transmitted on the time and frequency indicated by a resource allocation grant. After transmitting the data using the calculated transmit power, the process ends at  612 . 
     If the mobile device has been granted a resource allocation that cannot be fulfilled in the transmission at  612  because of power limitations in the mobile device (e.g., a combination of transmit power and MCS cannot be achieved because the combination exceeds the maximum power of the mobile device), the mobile device has several options: (1) the mobile device can transmit using a lower power; (2) the mobile device can transmit using a lower MCS level; (3) the mobile device can transmit on a reduced number of resource blocks; (4) the mobile device can repeat the request for resource allocation (e.g., repeat the synch RACH message  214 ), wherein the repeated request includes an indication of the resource utilization limitation (e.g.,  308 ), which limitation caused the previous grant to exceed the mobile device power limitation. 
     Although the invention is described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. For example, while the techniques and apparatus for controlling a transmit power in a mobile device may vary widely, one or more embodiments can be used in a system operating according to the 3GPP LTE standard. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element of any or all the claims. 
     Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements.

Metadata:
Filing Date: 20190528
Publication Date: 20210907
Grant Date: 20210907
Priority Date: 20070319
Inventors: OTERI, OGHENEKOME
MCCOY, JAMES
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W74/0833", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/365", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/0473", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/242", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/241", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/365", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/18", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/365", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/247", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/241", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/247", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/262", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/262", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/241", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/247", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/18", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W52/146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/241", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/365", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/262", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/262", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/23", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 39766322