Patent Publication Number: US-10785727-B2

Title: Uplink power prioritization for short TTI

Description:
PRIORITY 
     This nonprovisional application is a U.S., National Stage Filing under 35 U.S.C. § 371 of international Patent Application Serial No. PCT/SE2017/050947 filed Sep. 28, 2017 and entitled “Uplink Power Prioritization for Short TTI” which claims priority to U.S. Provisional Patent Application No. 62/402,370 filed Sep. 30, 2016 both of which are hereby incorporated by reference in, their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates, in general, to wireless communications and, more particularly, uplink power prioritization for short transmission time interval. 
     BACKGROUND 
     Latency Reduction with Short Subframes 
     Packet data latency is one of the performance metrics that vendors, operators and also end-users (via speed test applications) regularly measure. Latency measurements are done in all phases of a radio access network system&#39;s lifetime, for example when verifying a new software release or system component, when deploying a system and when the system is in commercial operation. 
     Shorter latency than previous generations of 3rd Generation Partnership Project (3GPP) radio access technologies (RATs) was one performance metric that guided the design of Long Term Evolution (LTE). LTE is also now recognized by the end-users to be a system that provides both faster access to internet and lower data latencies than previous generations of mobile radio technologies. 
     Packet data latency is important not only for the perceived responsiveness of the system; it is also a parameter that indirectly influences the throughput of the system. Hyper Text Transfer Protocol (HTTP)/Transmission Control Protocol (TCP) is the dominating application and transport layer protocol suite used on the internet today. According to HTTP Archive (http://httparchive.org/trends.php), the typical size of HTTP based transactions over the internet are in the range of a few 10 s of Kbyte up to 1 Mbyte. In this size range, the TCP slow start period is a significant part of the total transport period of the packet stream. During TCP slow start, the performance is latency limited. Hence, improved latency can rather easily be shown to improve the average throughput for these types of TCP based data transactions. Radio resource efficiency could be positively impacted by latency reductions. For example, lower packet data latency could increase the number of transmissions possible within a certain delay bound. Hence, higher Block Error Rate (BLER) targets could be used for the data transmissions, freeing up radio resources and potentially improving the capacity of the system. 
     One area to address when it comes to packet latency reductions is the reduction of transport time of data and control signaling, by addressing the length of a transmission time interval (TTI). In LTE Release 8, a TTI corresponds to one subframe of length 1 millisecond (ms). One such 1 ms TTI is constructed by using 14 Orthogonal Frequency Division Multiplexing (OFDM) or Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbols in the case of normal cyclic prefix (CP) and 12 OFDM or SC-FDMA symbols in the case of extended CP. In LTE Release 13, a study item is starting during 2015 with the goal of specifying transmissions with shorter TTIs that are much shorter than the LTE Release 8 TTI. 
     The shorter TTIs can be decided to have any duration in time and comprise resources on a number of OFDM or SC-FDMA symbols within a 1 ms subframe. As one example, the duration of the short TTI (sTTI) may be 0.5 ms (i.e., seven OFDM or SC-FDMA symbols for the case with normal cyclic prefix). As another example, the duration of the short TTI may be 2 symbols. 
     Power Control for PUSCH and sPUSCH 
     Power control for Physical Uplink Shared Channel (PUSCH) is defined in 3GPP TS 36.213 as, for subframe i and serving cell c, 
                   P     PUSCH   ,   c       ⁡     (   i   )       =     min   ⁢     {               10   ⁢           ⁢       log   10     ⁡     (           P   ^       CMAX   ,   c       ⁡     (   i   )       -         P   ^     PUCCH     ⁡     (   i   )         )         ,     ⁢                         10   ⁢           ⁢       log   10     ⁡     (       M     PUSCH   ,   c       ⁡     (   i   )       )         +       P       O   ⁢   _   ⁢   PUSCH     ,   c       ⁡     (   j   )       +                       ⁢           α   c     ⁡     (   j   )       ·     PL   c       +       Δ     TF   ,   c       ⁡     (   i   )       +       f   c     ⁡     (   i   )                 }         ,         
where:
         {circumflex over (P)} CMAX,c (i) is the maximum transmit power in linear scale;   {circumflex over (P)} PUCCH (i) the power of simultaneously transmitted Physical Uplink Control Channel (PUCCH) in linear scale, is equal to zero if no PUCCH is transmitted;   M PUSCH,c (i) is the number of resource blocks (RBs);   P O_PUSCH,c (j) is the target of received power signaled to the user equipment (UE) over Radio Resource Control (RRC);   α c (j)·PL c  is the scaled DL path loss estimate, with 0≤α c (j)≤1 signaled to the UE over RRC;   Δ TF,c (i) is an adjustment factor depending on the number of coded bits that is exactly specified in 3GPP TS 36.213; and   f c (i) is the closed loop power control derived from what δ PUSCH  which is signaled to the UE in the uplink (UL) grant. Two methods exist today in LTE to calculate f c , either accumulation based or not. If accumulation-based calculation is not activated, f c (i) follows directly the value of δ PUSCH  indicated in the UL grant. If accumulation-based calculation is activated, f c (i) is updated according to δ PUSCH  in the UL grant and its previous value f c (i−1) according to f c (i)=f c (i−1)+δ PUSCH,c (i−K PUSCH ), K PUSCH  represents the delay between the UL grant and the UL data transmission (Tx).
 
The power control for sPUSCH has not been defined yet, but is likely to be based on the power control of PUSCH. Similar equation and parameters as listed above can be used.
 
Power Control for PUCCH and sPUCCH
       

     Power control for Physical Uplink Control Channel (PUCCH) is defined in 3GPP TS 36.213 as, for subframe i and serving cell c, 
                 P   PUCCH     ⁡     (   i   )       =     min   ⁢     {                 P     CMAX   ,   c       ⁡     (   i   )       ,     ⁢                         P     0   ⁢     _   ⁢   PUCCH         +     PL   c     +     h   ⁡     (       n   CQI     ,     n   HARQ     ,     n   SR       )       +                       ⁢         Δ     F   ⁢   _   ⁢   PUCCH       ⁡     (   F   )       +       Δ   TxD     ⁡     (     F   ′     )       +     g   ⁡     (   i   )                 }             
for PUCCH format 1/1a/1b/2/2a/2b/3 and
 
                 P   PUCCH     ⁡     (   i   )       =     min   ⁢     {                 P     CMAX   ,   c       ⁡     (   i   )       ,     ⁢                         P     0   ⁢     _   ⁢   PUCCH         +     PL   c     +     10   ⁢       log   10     ⁡     (       M     PUCCH   ,   c       ⁡     (   i   )       )         +                       ⁢         Δ     TF   ,   c       ⁡     (   i   )       +       Δ     F   ⁢   _   ⁢   PUCCH       ⁡     (   F   )       +     g   ⁡     (   i   )                 }             
for PUCCH format 4/5,
 
where:
         P CMAX,c (i) is the maximum transmit power;   P O_PUCCH  is the target of received power;   PL c  is the downlink path loss estimate;   h(n CQI , n HARQ , n SR ) is a PUCCH format dependent value that reflects cases with larger payload;   M PUCCH,c (i) is the number of RBs for PUCCH format 5, equals 1 for all other formats;   Δ F_PUCCH (F) is a relation in dB between PUCCH format F and PUCCH format 1a;   Δ TT,c (i) is an adjustment factor depending on the number of coded bits that is exactly specified in 3GPP TS 36.213;   Δ TxD (F′) depends on the number of antenna ports configured for PUCCH; and   g(i) is the closed loop power control state and is updated using δ PUCCH  signalled in the DL assignment.
 
The power control for sPUCCH has not been defined yet, but is likely to be based on the power control of PUCCH. Similar equations and parameters as listed above can be used.
 
UL Power Prioritization Among UL Physical Channels of 1 ms TTI
       

     For 1 ms UL TTI in LTE, if the UE has parallel transmission of two or more UL physical channels and does not have enough power for parallel transmission of all UL physical channels, the UL power is distributed among the uplink physical channels according to a priority of the 1 ms UL TTIs. However, the priority information for the 1 ms UL TTIs may not provide sufficient information for distributing UL power in some scenarios. For example, the priority of the UL TTIs does not provide information about how to distribute UL power for scenarios in which the parallel transmissions include one or more UL sTTIs. 
     SUMMARY 
     An object of certain embodiments includes improving distribution of UL power for scenarios in which a wireless device has parallel transmission of two or more UL physical channels and does not have enough power for parallel transmission of all UL physical channels. Certain embodiments improve distribution of UL power by providing rules for prioritizing sTTI transmissions. As an example, certain embodiments prioritize sTTI transmissions over TTI transmissions. As another example, certain embodiments prioritize sTTI transmissions comprising control information over sTTI transmissions without control information. 
     According to certain embodiments, a method is disclosed for use in a wireless device. The method comprises determining that the wireless device has scheduled parallel transmissions during a subframe. The parallel transmissions are scheduled on two or more uplink, UL, physical channels, and the parallel transmissions comprise one or more short transmission time interval, sTTI, transmissions. The method further comprises distributing UL power among the parallel transmissions. The UL power is distributed according to at least one of the following prioritization rules: (1) sTTI transmissions comprising control information are prioritized over sTTI transmissions comprising data without any control information; and/or (2) transmissions with shorter transmission time intervals are prioritized over transmissions with longer transmission time intervals. 
     According to certain embodiments, a wireless device comprises memory and processing circuitry. The memory is operable to store instructions, and the processing circuitry is operable to execute the instructions. By executing the instructions, the wireless device is operable to determine that the wireless device has scheduled parallel transmissions during a subframe. The parallel transmissions are scheduled on two or more uplink, UL, physical channels, and the parallel transmissions comprise one or more short transmission time interval, sTTI, transmissions. The wireless device is further operable to distribute UL power among the parallel transmissions. The UL power is distributed according to at least one of the following prioritization rules: (1) sTTI transmissions comprising control information are prioritized over sTTI transmissions comprising data without any control information; and/or (2) transmissions with shorter transmission time intervals are prioritized over transmissions with longer transmission time intervals. 
     According to certain embodiments, a computer program product comprising a non-transitory computer readable medium. The non-transitory computer readable medium stores computer readable program code. The computer readable program code comprises program code for determining that the wireless device has scheduled parallel transmissions during a subframe. The parallel transmissions are scheduled on two or more uplink, UL, physical channels, and the parallel transmissions comprise one or more short transmission time interval, sTTI, transmissions. The computer readable program code further comprises program code for distributing UL power among the parallel transmissions. The UL power is distributed according to at least one of the following prioritization rules: (1) sTTI transmissions comprising control information are prioritized over sTTI transmissions comprising data without any control information; and/or (2) transmissions with shorter transmission time intervals are prioritized over transmissions with longer transmission time intervals. 
     Certain embodiments of the above-described method, wireless device, and/or computer program product may include one or more of the following features:
         In certain embodiments, the method/wireless device/computer program product determines that the wireless device has a limited UL power for the parallel transmissions scheduled during the subframe.   In certain embodiments, the prioritization rules for distributing UL power among the parallel transmissions comprise prioritizing the sTTI transmissions in the following order: (1) sTTI transmissions that use a control channel to transmit control information, (2) sTTI transmissions that use a data channel to transmit control information, and (3) sTTI transmissions that use the data channel to transmit data without any control information.   In certain embodiments the method/wireless device/computer program product uses a common factor to scale the UL power for the sTTI transmissions that use the data channel to transmit data (rather than control information) based on determining that the UL power is not sufficient for the parallel transmissions.   In certain embodiments, the parallel transmissions comprise one or more TTI transmissions, each having a duration of 1 ms (whereas each of the one or more sTTI transmissions has a duration of less than 1 ms). The prioritization rules for distributing the UL power among the parallel transmissions prioritize the one or more sTTI transmissions over the one or more TTI transmissions.   In certain embodiments, the parallel transmissions comprise one or more TTI transmissions configured according to Long Term Evolution, LTE, Release 8. The prioritization rules for distributing the UL power among the parallel transmissions prioritize the one or more sTTI transmissions over the one or more TTI transmissions, each sTTi transmission having a shorter duration than each TTI transmission.   In certain embodiments, distributing the UL power among the parallel transmissions comprises reserving a first amount of UL power for the one or more sTTI transmissions scheduled on the control channel. The first amount of UL power is reserved upon determining that one or more of the sTTI transmissions are scheduled on a control channel. A first amount of remaining UL power is calculated by deducting the reserved first amount of UL power from a total UL power allowed or available to the wireless device. A second amount of UL power is reserved from the first amount of remaining UL power for the one or more sTTI transmissions scheduled on the data channel and including the control information. The second amount of power is reserved upon determining that one or more of the sTTI transmissions are scheduled on a data channel and include the control information. A second amount of remaining UL power is calculated by deducting the reserved second amount of UL power from the calculated first amount of remaining UL power. A third amount of UL power is reserved from the second amount of remaining UL power for the one or more sTTI transmissions scheduled on the data channel and not including the control information. The third amount of UL power is reserved upon determining that one or more of the sTTI transmissions are scheduled on the data channel and do not include the control information.   In certain embodiments, the method/wireless device/computer program product transmits the parallel transmissions according to the determined distribution of UL power.   In certain embodiments, the transmissions with the shorter transmission time intervals are scheduled on a different carrier than the transmissions with the longer transmission time intervals.   In certain embodiments, the prioritization rules for distributing UL power prioritize sTTI transmissions that include control information over sTTI transmissions that do not include control information, and prioritize TTI transmissions that include control information over TTI transmissions that do not include control information. For example, the prioritization rules for distributing UL power may prioritize transmissions in the following order: (1) sTTI transmissions that include control information, (2) sTTI transmissions that do not include control information, (3) TTI transmissions that include control information, (4) TTI transmissions that do not include control information.   In certain embodiments, the one or more sTTI transmissions are scheduled only at the beginning of the subframe. In this case, distributing the UL power for the subframe may comprise distributing a first amount of UL power for the one or more sTTI transmissions, calculating a remaining UL power by deducting the first amount of UL power from a total UL power allowed or available to the wireless device, and distributing the remaining UL power for the TTI transmissions. In the example, the first amount of UL power (the UL power for the one or more sTTI transmission) satisfies the UL power needed for the one or more sTTI transmissions.   In certain embodiments, distributing the UL power for the subframe comprises determining all of the UL transmissions that have been scheduled for the subframe as of a pre-determined time (t 0 ). The pre-determined time is based on an amount of time before the start of the subframe (t start -Δ). A first amount of UL power is distributed for the sTTI transmissions. The first amount of UL power satisfies the UL power needed for the one or more sTTI transmissions that have been scheduled for the subframe as of the pre-determined time (t 0 ) is distributed for the sTTI transmissions. The remaining UL power is calculated by deducting the first amount of UL power from a total UL power allowed or available to the wireless device. The remaining UL power is distributed for the TTI transmissions. In certain embodiments, less UL power is distributed to the TTI transmissions for a portion of the subframe during which the sTTI transmissions have been scheduled, and more UL power is distributed to the TTI for a portion of the subframe during which the sTTI transmissions have not been scheduled.   In certain embodiments, each of the one or more sTTI transmissions is scheduled in the middle of the subframe.   In certain embodiments, it may be determined that at least one of the one or more sTTI transmissions in the subframe did not get scheduled until after the pre-determined time (t 0 ). In that case, the UL power available for the TTI transmissions can be re-distributed during transmission of the sTTI(s) that did not get scheduled until after the pre-determined time (t 0 ).   In certain embodiments, the length of the subframe is 1 ms. In certain embodiments, the one or more sTTI transmissions comprise a first sTTI transmission and a second sTTI transmission. The first and second sTTI transmissions each has a duration less than 1 millisecond, and the first sTTI has a shorter duration than the second sTTI. The prioritization rule for distributing UL power prioritizes the shorter sTTI (first sTTI) over the longer sTTI (second sTTI).       

     Certain embodiments of the present disclosure may provide one or more technical advantages. For example, certain embodiments may advantageously enable a UE to distribute its power with the most appropriate priority in case the UE has not enough power for all UL physical channels. Certain embodiments may prioritize UL power distribution to UL transmissions having an sTTI over UL transmissions having a TTI. An advantage of prioritizing UL power distribution to sTTIs may be to ensure sufficient UL power is allocated to minimize delays for sTTIs (which are typically less delay-tolerant than TTIs). Certain embodiments may prioritize UL power distribution to UL transmissions that include control information over UL transmissions that do not include control information. An advantage of prioritizing UL power distribution to control information may be to ensure sufficient UL power is allocated to minimize delays for control information (which may be important for optimal control). Other advantages may be readily apparent to one having skill in the art. Certain embodiments may have none, some, or all of the recited advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the disclosed embodiments and their features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of an exemplary wireless communications network, in accordance with certain embodiments; 
         FIG. 2  illustrates an example of UL power level on 1 ms TTI carrier with potential parallel UL sTTI transmission in another carrier, in accordance with certain embodiments; 
         FIG. 3  illustrates an example of how to consider potential parallel UL sTTI transmission when setting UL power for 1 ms UL TTI, in accordance with certain embodiments; 
         FIG. 4  illustrates a comparison of power level for 1 ms UL TTI when potential parallel UL sTTI transmissions are considered and when they are not considered, in accordance with certain embodiments; 
         FIG. 5  is a flow diagram of a method in a user equipment, in accordance with certain embodiments; 
         FIG. 6  is a flow diagram of a method in a user equipment, in accordance with certain embodiments; 
         FIG. 7  is a block schematic of an exemplary wireless device, in accordance with certain embodiments; 
         FIG. 8  is a block schematic of an exemplary network node, in accordance with certain embodiments; 
         FIG. 9  is a block schematic of an exemplary radio network controller or core network node, in accordance with certain embodiments; 
         FIG. 10  is a block schematic of an exemplary wireless device, in accordance with certain embodiments; 
         FIG. 11  is a block schematic of an exemplary network node, in accordance with certain embodiments; and 
         FIG. 12  is a flow diagram of a method in a wireless device, in accordance with certain embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     As described above, for 1 ms UL TTI in LTE, if the UE has parallel transmission of two or more UL physical channels and does not have enough power for parallel transmission of all UL physical channels, the UL power is distributed among the uplink physical channels according to priority. For example, UL power may be distributed according to the following priority: (1) PUCCH first; (2) PUSCH with UCI (UL control Information); (3) PUSCH without UCI; (4) PRACH; and (5) SRS. Certain UEs can also support sTTI transmissions (an sTTI transmission has a duration less than 1 ms and is therefore shorter than a 1 ms TTI transmission). However, power control for physical channels on sTTI has not yet been defined. Hence, there is no current solution on how to control power on sPUSCH and sPUCCH, and more specifically how to prioritize power among UL physical channels used for sTTI and also between UL physical channels used for sTTI and 1 ms TTI. 
     The present disclosure contemplates various embodiments that may address these and other deficiencies. In certain embodiments, a methods to support UL power prioritization among UL channels for sTTI are disclosed. According to one example embodiment, UL power is prioritized among sTTI UL channels and between sTTI and 1 ms TTI UL channels. In addition, a method is disclosed to set the power for 1 ms UL TTI considering the sTTI scheduled for the overlapping subframe. The various embodiments described herein may advantageously enable a UE to distribute its power with the most appropriate priority in case the UE has not enough power for all UL physical channels. Other advantages may be readily apparent to one having skill in the art. Certain embodiments may have none, some, or all of the recited advantages. 
       FIG. 1  is a block diagram illustrating an embodiment of a network  100 , in accordance with certain embodiments. Network  100  includes one or more UE(s)  110  (which may be interchangeably referred to as wireless devices  110 ) and one or more network node(s)  115  (which may be interchangeably referred to as eNBs  115 ). UEs  110  may communicate with network nodes  115  over a wireless interface. For example, a UE  110  may transmit wireless signals to one or more of network nodes  115 , and/or receive wireless signals from one or more of network nodes  115 . The wireless signals may contain voice traffic, data traffic, control signals, and/or any other suitable information. In some embodiments, an area of wireless signal coverage associated with a network node  115  may be referred to as a cell  125 . In some embodiments, UEs  110  may have device-to-device (D2D) capability. Thus, UEs  110  may be able to receive signals from and/or transmit signals directly to another UE. 
     In certain embodiments, network nodes  115  may interface with a radio network controller. The radio network controller may control network nodes  115  and may provide certain radio resource management functions, mobility management functions, and/or other suitable functions. In certain embodiments, the functions of the radio network controller may be included in network node  115 . The radio network controller may interface with a core network node. In certain embodiments, the radio network controller may interface with the core network node via an interconnecting network  120 . Interconnecting network  120  may refer to any interconnecting system capable of transmitting audio, video, signals, data, messages, or any combination of the preceding. Interconnecting network  120  may include all or a portion of a public switched telephone network (PSTN), a public or private data network, a local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), a local, regional, or global communication or computer network such as the Internet, a wireline or wireless network, an enterprise intranet, or any other suitable communication link, including combinations thereof. 
     In some embodiments, the core network node may manage the establishment of communication sessions and various other functionalities for UEs  110 . UEs  110  may exchange certain signals with the core network node using the non-access stratum layer. In non-access stratum signaling, signals between UEs  110  and the core network node may be transparently passed through the radio access network. In certain embodiments, network nodes  115  may interface with one or more network nodes over an internode interface, such as, for example, an X2 interface. 
     As described above, example embodiments of network  100  may include one or more wireless devices  110 , and one or more different types of network nodes capable of communicating (directly or indirectly) with wireless devices  110 . 
     In some embodiments, the non-limiting term UE is used. UEs  110  described herein can be any type of wireless device capable of communicating with network nodes  115  or another UE over radio signals. UE  110  may also be a radio communication device, target device, D2D UE, machine-type-communication UE or UE capable of machine to machine communication (M2M), low-cost and/or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), etc. UE  110  may operate under either normal coverage or enhanced coverage with respect to its serving cell. The enhanced coverage may be interchangeably referred to as extended coverage. UE  110  may also operate in a plurality of coverage levels (e.g., normal coverage, enhanced coverage level  1 , enhanced coverage level  2 , enhanced coverage level  3  and so on). In some cases, UE  110  may also operate in out-of-coverage scenarios. 
     Also, in some embodiments generic terminology, “radio network node” (or simply “network node”) is used. It can be any kind of network node, which may comprise a base station (BS), radio base station, Node B, base station (BS), multi-standard radio (MSR) radio node such as MSR BS, evolved Node B (eNB), network controller, radio network controller (RNC), base station controller (BSC), relay node, relay donor node controlling relay, base transceiver station (BTS), access point (AP), radio access point, transmission points, transmission nodes, Remote Radio Unit (RRU), Remote Radio Head (RRH), nodes in distributed antenna system (DAS), Multi-cell/multicast Coordination Entity (MCE), core network node (e.g., MSC, MME, etc.), O&amp;M, OSS, SON, positioning node (e.g., E-SMLC), MDT, or any other suitable network node. 
     The terminology such as network node and UE should be considered non-limiting and does in particular not imply a certain hierarchical relation between the two; in general “eNodeB” could be considered as device  1  and “UE” device  2 , and these two devices communicate with each other over some radio channel. 
     Example embodiments of UE  110 , network nodes  115 , and other network nodes (such as radio network controller or core network node) are described in more detail below with respect to  FIGS. 7-11 . 
     Although  FIG. 1  illustrates a particular arrangement of network  100 , the present disclosure contemplates that the various embodiments described herein may be applied to a variety of networks having any suitable configuration. For example, network  100  may include any suitable number of UEs  110  and network nodes  115 , as well as any additional elements suitable to support communication between UEs or between a UE and another communication device (such as a landline telephone). Furthermore, although certain embodiments may be described as implemented in a Long Term Evolution (LTE) network, the embodiments may be implemented in any appropriate type of telecommunication system supporting any suitable communication standards (including 5G standards) and using any suitable components, and are applicable to any radio access technology (RAT) or multi-RAT systems in which a UE receives and/or transmits signals (e.g., data). For example, the various embodiments described herein may be applicable to LTE, LTE-Advanced, 5G, UMTS, HSPA, GSM, cdma2000, WCDMA, WiMax, UMB, WiFi, another suitable radio access technology, or any suitable combination of one or more radio access technologies. Although certain embodiments may be described in the context of wireless transmissions in the downlink, the present disclosure contemplates that the various embodiments are equally applicable in the uplink. 
     Power Prioritization among UL Physical Channels of Short TTI 
     In certain embodiments, if a UE has parallel transmission of two or more UL physical channels of short TTI and does not have enough power for parallel transmission of all UL physical channels, the UL power is distributed among the uplink physical channels according to the following priority:
         1. sPUCCH first   2. sPUSCH with UCI (UL control Information)   3. sPUSCH without UCI
 
This enables to ensure that control-related information is prioritized over data.
       

     In certain embodiments, a method in a UE is disclosed. According to one example embodiment, the method comprises the following actions:
         1. The UE should first reserve power for sPUCCH if it has a sPUCCH transmission. The power reserved for a potential sPUCCH transmission follows the power control equation. An example is provided for PUCCH format 1/1a/1b/2/2a/2b/3:       

                 P   PUCCH     ⁡     (   i   )       =     min   ⁢     {                 P     CMAX   ,   c       ⁡     (   i   )       ,     ⁢                         P     0   ⁢     _   ⁢   PUCCH         +     PL   c     +     h   ⁡     (       n   CQI     ,     n   HARQ     ,     n   SR       )       +                       ⁢         Δ     F   ⁢   _   ⁢   PUCCH       ⁡     (   F   )       +       Δ   TxD     ⁡     (     F   ′     )       +     g   ⁡     (   i   )                 }             
Another example is provided for PUCCH format 4/5:
 
     
       
         
           
             
               
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              The remaining power is then computed by removing the power reserved for a potential sPUCCH from the total available or allowed Tx power of the UE. 
             2. From the remaining power after action 1, power is then reserved for sPUSCH with UCI in case there is such a transmission in the same sTTI. The power reserved for sPUSCH with UCI follows the power control equation where an example is provided as follows: 
           
         
       
    
     
       
         
           
             
               
                 
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              The remaining power is then computed by removing the power reserved for sPUSCH with UCI from the Tx power of the UE remaining after action 1. 
             3. The remaining power after action 2 is then dedicated to sPUSCH without UCI transmissions. First, the power needed for sPUSCH without UCI transmissions follows the power control equation where an example is provided as follows: 
           
         
       
    
     
       
         
           
             
               
                 
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              If more power is needed than what is left from action 2, the power is scaled with the same factor for all sPUSCH without UCI transmissions so that the remaining power after action 2 is not exceeded. Note that there can be parallel sPUSCH without UCI transmissions in multiple parallel frequency carriers. In that case, there is no reason to prioritize a sPUSCH without UCI transmission on a particular carrier compared to the sPUSCH without UCI transmissions on the other carriers. That&#39;s why the remaining power after action 2 is scaled in the same way among all parallel sPUSCH without UCI transmissions over different carriers.
 
Power Prioritization Between UL Physical Channels of Short TTI and 1 ms TTI
 
           
         
       
    
     A UE can have received UL grants for overlapping or parallel short TTI UL transmission and 1 ms TTI UL transmission. This may happen on the same carrier or, more likely, this may happen on different carriers. In the latter case, a 1 ms TTI UL transmission is scheduled for UE  0  on carrier  0  and a sTTI UL transmission is scheduled in the same subframe for the same UE on carrier  1 . If UE  0  is not power limited, the power for 1 ms UL TTI and the power for UL sTTI is calculated following the example equations described above. One consideration is how the power should be distributed if the UE is power limited. 
     Short TTI are used for time-critical services that would benefit from lower latency compared to 1 ms TTI. The general rule should thus be to prioritize sTTI over 1 ms TTI since that will to the furthest extent make sure that latency critical sTTI transmissions are carried out as soon as possible. 
     According to another example embodiment, if the UE is power limited, the following actions should be followed to distribute its power:
         1. The UE should first calculate the power that is needed for the sTTI UL transmissions. Several UL sTTI transmissions can be conducted in parallel (e.g., sPUCCH and sPUSCH or sPUSCH with UCI and sPUSCH). The prioritization among those UL sTTI channels should follow the method described above with respect to power prioritization among UL physical channels of short TTI. After having distributed the power among sTTI channels, the UE calculates the remaining power.   2. Given the remaining power after action 1, the UE should distribute the power among 1 ms UL TTI channels according to the specified prioritization rules for 1 ms UL TTI physical channels described above.
 
The procedure described just above works well if sTTI transmissions are scheduled only at the beginning of a subframe. In this case, the 1 ms UL TTI transmission on carrier  0  starts at exactly the same time as the UL sTTI transmission on carrier  1 . Because of this, the UE, which then has all information available before transmission starts, can compute the power for sTTI and for 1 ms TTI before starting the transmission and can avoid changing output power during the subframe. This is depicted in  FIG. 2  on subframe n.
       

       FIG. 2  illustrates an example of UL power level on 1 ms TTI carrier with potential parallel UL sTTI transmission in another carrier, in accordance with certain embodiments. Since the considered UE is power-limited, it can be seen that in subframe n−1 where there was only a 1 ms UL TTI transmission and no parallel UL sTTI transmission, the power level used for the 1 ms UL TTI transmission was higher than in subframe n that has parallel UL sTTI transmissions. 
     The situation becomes more complicated when the sTTI transmissions occur in the middle of a subframe as in the example depicted in  FIG. 2  and subframe n+1. In that case, the 1 ms UL TTI started already at the subframe boundary with a given power and this power needs to be adjusted and lowered in the middle of the subframe due to sTTI transmissions. This may not be desirable. 
     According to another example embodiment, a method is disclosed that may advantageously enable the UE to avoid as much as possible large power adjustment in the middle of the subframe for 1 ms UL TTI in that case. Such an embodiment is described below with respect to  FIGS. 3 and 4 . 
       FIG. 3  illustrates an example of how to consider potential parallel UL sTTI transmission when setting UL power for 1 ms UL TTI, in accordance with certain embodiments. In such an embodiment, the UE computes shortly before the subframe start the power needed for potential 1 ms UL TTI and sTTI transmissions. In this example, this happens at t 0 =subframe start−Δ. At this time, the UE should check all UL transmissions scheduled for the subframe n. This includes the 1 ms TTI UL transmissions and short TTI UL transmissions. In this additional embodiment, the UE sets the power for the 1 ms TTI transmissions considering all the short TTI UL transmissions that the UE is aware of at t 0 . So, if the UE is power limited, the reduced power for the 1 ms UL TTI is used from the subframe start and not only when the sTTI are actually transmitted in the middle of the subframe as was the case in  FIG. 2  described above. Since the delay d between the UL grant for short TTI transmission and the actual UL sTTI transmission, not all sTTI transmissions occuring in the following subframe are known to the UE at time t 0 . 
     In  FIG. 3 , the last UL sTTI transmission is not known to the UE at time to. So, this means that there can be a variation of the power used for the 1 ms UL TTI during the subframe but it can be much smaller compared to not applying this embodiment. 
       FIG. 4  illustrates a comparison of power level for 1 ms UL TTI when potential parallel UL sTTI transmissions are considered and when they are not considered, in accordance with certain embodiments.  FIG. 4  compares the power level for 1 ms TTI if the scheduled UL sTTI are considered for the overlapping subframe and when they are not considered. It can be seen from  FIG. 4  that with the additional embodiment, the power of the 1 ms UL TTI is set to a lower value from the subframe start due to the UE power limitation and the consideration of scheduled sTTI in the same subframe. Due to a short delay d not all sTTI of the subframe are known to the UE at the time of setting the power for 1 ms UL TTI, therefore there is a power level change for 1 ms TTI in the middle of the subframe, but it is smaller than without considering the known scheduled sTTIs for the same subframe as shown in  FIG. 4 . 
       FIG. 5  is a flow diagram of a method in a user equipment. The method begins at action  504 , where the UE determines that the UE has parallel transmissions scheduled on two or more UL physical channels, the parallel transmissions comprising sTTI transmissions. At action  508 , the UE distributes UL power among the parallel transmissions scheduled on the two or more UL physical channels such that sTTI transmissions containing control information are prioritized over sTTI transmissions containing data. 
       FIG. 6  is a flow diagram of a method in a user equipment. The method begins at action  604 , where the UE determines, before the start of a first subframe, an amount of power needed for one or more UL transmissions scheduled in the first subframe, the one or more UL transmissions scheduled in the first subframe comprising at least one of an UL transmission having a TTI of 1 ms and an UL transmission having a short TTI. At action  608 , the UE sets a first power level for the UL transmission having the TTI of 1 ms based on the UL transmission having the short TTI scheduled in the first subframe. At action  612 , the UE transmits the one or more UL transmissions having the TTI of 1 ms at the set first power level. 
       FIG. 7  is a block schematic of an exemplary wireless device, in accordance with certain embodiments. Wireless device  110  may refer to any type of wireless device communicating with a node and/or with another wireless device in a cellular or mobile communication system. Examples of wireless device  110  include a mobile phone, a smart phone, a PDA (Personal Digital Assistant), a portable computer (e.g., laptop, tablet), a sensor, a modem, a machine-type-communication (MTC) device/machine-to-machine (M2M) device, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, a D2D capable device, or another device that can provide wireless communication. A wireless device  110  may also be referred to as UE, a station (STA), a device, or a terminal in some embodiments. Wireless device  110  includes transceiver  710 , processing circuitry  720 , and memory  730 . In some embodiments, transceiver  710  facilitates transmitting wireless signals to and receiving wireless signals from network node  115  (e.g., via antenna  740 ), processing circuitry  720  executes instructions to provide some or all of the functionality described above as being provided by wireless device  110 , and memory  730  stores the instructions executed by processing circuitry  720 . 
     Processing circuitry  720  may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of wireless device  110 , such as the functions of wireless device  110  (e.g., UE) described in relation to  FIGS. 1-6 and/or 12 . For example, processing circuitry  720  may perform functions related to distributing UL power among parallel transmissions that include one or more sTTI transmissions. In some embodiments, processing circuitry  720  may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs) and/or other logic. 
     Memory  730  is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by a processor. Examples of memory  730  include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by processing circuitry  720 . 
     Other embodiments of wireless device  110  may include additional components beyond those shown in  FIG. 7  that may be responsible for providing certain aspects of the wireless device&#39;s functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solution described above). As just one example, wireless device  110  may include input devices and circuits, output devices, and one or more synchronization units or circuits, which may be part of the processing circuitry  720 . Input devices include mechanisms for entry of data into wireless device  110 . For example, input devices may include input mechanisms, such as a microphone, input elements, a display, etc. Output devices may include mechanisms for outputting data in audio, video and/or hard copy format. For example, output devices may include a speaker, a display, etc. 
       FIG. 8  is a block schematic of an exemplary network node, in accordance with certain embodiments. Network node  115  may be any type of radio network node or any network node that communicates with a UE and/or with another network node. Examples of network node  115  include an eNodeB, a node B, a base station, a wireless access point (e.g., a Wi-Fi access point), a low power node, a base transceiver station (BTS), relay, donor node controlling relay, transmission points, transmission nodes, remote RF unit (RRU), remote radio head (RRH), multi-standard radio (MSR) radio node such as MSR BS, nodes in distributed antenna system (DAS), O&amp;M, OSS, SON, positioning node (e.g., E-SMLC), MDT, or any other suitable network node. Network nodes  115  may be deployed throughout network  100  as a homogenous deployment, heterogeneous deployment, or mixed deployment. A homogeneous deployment may generally describe a deployment made up of the same (or similar) type of network nodes  115  and/or similar coverage and cell sizes and inter-site distances. A heterogeneous deployment may generally describe deployments using a variety of types of network nodes  115  having different cell sizes, transmit powers, capacities, and inter-site distances. For example, a heterogeneous deployment may include a plurality of low-power nodes placed throughout a macro-cell layout. Mixed deployments may include a mix of homogenous portions and heterogeneous portions. 
     Network node  115  may include one or more of transceiver  810 , processing circuitry  820 , memory  830 , and network interface  840 . In some embodiments, transceiver  810  facilitates transmitting wireless signals to and receiving wireless signals from wireless device  110  (e.g., via antenna  950 ), processing circuitry  820  executes instructions to provide some or all of the functionality described above as being provided by a network node  115 , memory  830  stores the instructions executed by processing circuitry  820 , and network interface  840  communicates signals to backend network components, such as a gateway, switch, router, Internet, Public Switched Telephone Network (PSTN), core network nodes or radio network controllers  130 , etc. 
     Processing circuitry  820  may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of network node  115 , such as those described above in relation to  FIGS. 1-6  above. In some embodiments, processing circuitry  820  may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, and/or other logic. 
     Memory  830  is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by a processor. Examples of memory  830  include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information. 
     In some embodiments, network interface  840  is communicatively coupled to processing circuitry  820  and may refer to any suitable device operable to receive input for network node  115 , send output from network node  115 , perform suitable processing of the input or output or both, communicate to other devices, or any combination of the preceding. Network interface  840  may include appropriate hardware (e.g., port, modem, network interface card, etc.) and software, including protocol conversion and data processing capabilities, to communicate through a network. 
     Other embodiments of network node  115  may include additional components beyond those shown in  FIG. 8  that may be responsible for providing certain aspects of the radio network node&#39;s functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above). The various different types of network nodes may include components having the same physical hardware but configured (e.g., via programming) to support different radio access technologies, or may represent partly or entirely different physical components. 
       FIG. 9  is a block schematic of an exemplary radio network controller or core network node  130 , in accordance with certain embodiments. Examples of network nodes can include a mobile switching center (MSC), a serving GPRS support node (SGSN), a mobility management entity (MME), a radio network controller (RNC), a base station controller (BSC), and so on. The radio network controller or core network node  130  includes processing circuitry  920 , memory  930 , and network interface  940 . In some embodiments, processing circuitry  920  executes instructions to provide some or all of the functionality described above as being provided by the network node, memory  930  stores the instructions executed by processing circuitry  920 , and network interface  940  communicates signals to any suitable node, such as a gateway, switch, router, Internet, Public Switched Telephone Network (PSTN), network nodes  115 , radio network controllers or core network nodes  130 , etc. 
     Processing circuitry  920  may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of the radio network controller or core network node  130 . In some embodiments, processing circuitry  920  may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, and/or other logic. 
     Memory  930  is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by a processor. Examples of memory  930  include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information. 
     In some embodiments, network interface  940  is communicatively coupled to processing circuitry  920  and may refer to any suitable device operable to receive input for the network node, send output from the network node, perform suitable processing of the input or output or both, communicate to other devices, or any combination of the preceding. Network interface  940  may include appropriate hardware (e.g., port, modem, network interface card, etc.) and software, including protocol conversion and data processing capabilities, to communicate through a network. 
     Other embodiments of the network node may include additional components beyond those shown in  FIG. 9  that may be responsible for providing certain aspects of the network node&#39;s functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solution described above). 
       FIG. 10  is a block schematic of an exemplary wireless device, in accordance with certain embodiments. Wireless device  110  may include one or more modules. For example, wireless device  110  may include a determining module  1010 , a communication module  1020 , a receiving module  1030 , an input module  1040 , a display module  1050 , and any other suitable modules. Wireless device  110  may perform the methods for uplink power prioritization for short TTI described with respect to  FIGS. 1-6 and/or 12 . 
     Determining module  1010  may perform the processing functions of wireless device  110 . For example, determining module  1010  may determine that the UE has parallel transmissions scheduled on two or more UL physical channels, the parallel transmissions comprising sTTI transmissions. As another example, determining module  1010  may distribute UL power among the parallel transmissions scheduled on the two or more UL physical channels such that sTTI transmissions containing control information are prioritized over sTTI transmissions containing data. As still another example, determining module  1010  may determine, before the start of a first subframe, an amount of power needed for one or more UL transmissions scheduled in the first subframe, the one or more UL transmissions scheduled in the first subframe comprising at least one of an UL transmission having a TTI of 1 ms and an UL transmission having a short TTI. As yet another example, determining module  1010  may set a first power level for the UL transmission having the TTI of 1 ms based on the UL transmission having the short TTI scheduled in the first subframe. Determining module  1010  may include or be included in one or more processors, such as processing circuitry  720  described above in relation to  FIG. 7 . Determining module  1010  may include analog and/or digital circuitry configured to perform any of the functions of determining module  1010  and/or processing circuitry  720  described above. The functions of determining module  1010  described above may, in certain embodiments, be performed in one or more distinct modules. 
     Communication module  1020  may perform the transmission functions of wireless device  110 . As one example, communication module  1020  may transmit the one or more UL transmissions having the TTI of 1 ms at the set first power level. Communication module  1020  may transmit messages to one or more of network nodes  115  of network  100 . Communication module  1020  may include a transmitter and/or a transceiver, such as transceiver  710  described above in relation to  FIG. 7 . Communication module  1020  may include circuitry configured to wirelessly transmit messages and/or signals. In particular embodiments, communication module  1020  may receive messages and/or signals for transmission from determining module  1010 . In certain embodiments, the functions of communication module  1020  described above may be performed in one or more distinct modules. 
     Receiving module  1030  may perform the receiving functions of wireless device  110 . Receiving module  1030  may include a receiver and/or a transceiver, such as transceiver  710  described above in relation to  FIG. 7 . Receiving module  1030  may include circuitry configured to wirelessly receive messages and/or signals. In particular embodiments, receiving module  1030  may communicate received messages and/or signals to determining module  1010 . 
     Input module  1040  may receive user input intended for wireless device  110 . For example, the input module may receive key presses, button presses, touches, swipes, audio signals, video signals, and/or any other appropriate signals. The input module may include one or more keys, buttons, levers, switches, touchscreens, microphones, and/or cameras. The input module may communicate received signals to determining module  1010 . 
     Display module  1050  may present signals on a display of wireless device  110 . Display module  1050  may include the display and/or any appropriate circuitry and hardware configured to present signals on the display. Display module  1050  may receive signals to present on the display from determining module  1010 . 
     Determining module  1010 , communication module  1020 , receiving module  1030 , input module  1040 , and display module  1050  may include any suitable configuration of hardware and/or software. Wireless device  110  may include additional modules beyond those shown in  FIG. 10  that may be responsible for providing any suitable functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the various solutions described herein). 
       FIG. 11  is a block schematic of an exemplary network node  115 , in accordance with certain embodiments. Network node  115  may include one or more modules. For example, network node  115  may include determining module  1110 , communication module  1120 , receiving module  1130 , and any other suitable modules. In some embodiments, one or more of determining module  1110 , communication module  1120 , receiving module  1130 , or any other suitable module may be implemented using one or more processors, such as processing circuitry  820  described above in relation to  FIG. 8 . In certain embodiments, the functions of two or more of the various modules may be combined into a single module. Network node  115  may perform the methods for effective MIB acquisition for MTC devices described above with respect to  FIGS. 1-6 . 
     Determining module  1110  may perform the processing functions of network node  115 . Determining module  1110  may include or be included in one or more processors, such as processing circuitry  820  described above in relation to  FIG. 8 . Determining module  1110  may include analog and/or digital circuitry configured to perform any of the functions of determining module  1110  and/or processing circuitry  820  described above. The functions of determining module  1110  may, in certain embodiments, be performed in one or more distinct modules. For example, in certain embodiments some of the functionality of determining module  1110  may be performed by an allocation module. 
     Communication module  1120  may perform the transmission functions of network node  115 . Communication module  1120  may transmit messages to one or more of wireless devices  110 . Communication module  1120  may include a transmitter and/or a transceiver, such as transceiver  810  described above in relation to  FIG. 8 . Communication module  1120  may include circuitry configured to wirelessly transmit messages and/or signals. In particular embodiments, communication module  1120  may receive messages and/or signals for transmission from determining module  1110  or any other module. 
     Receiving module  1130  may perform the receiving functions of network node  115 . Receiving module  1130  may receive any suitable information from a wireless device. Receiving module  1130  may include a receiver and/or a transceiver, such as transceiver  810  described above in relation to  FIG. 8 . Receiving module  1130  may include circuitry configured to wirelessly receive messages and/or signals. In particular embodiments, receiving module  1130  may communicate received messages and/or signals to determining module  1110  or any other suitable module. 
     Determining module  1110 , communication module  1120 , and receiving module  1130  may include any suitable configuration of hardware and/or software. Network node  115  may include additional modules beyond those shown in  FIG. 11  that may be responsible for providing any suitable functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the various solutions described herein). 
       FIG. 12  is a flow diagram of a method for use in a wireless device  110 , in accordance with certain embodiments. At action  1204 , the method determines that the wireless device  110  has scheduled parallel transmissions during a subframe (such as a 1 ms subframe described in LTE Release 8). The parallel transmissions are scheduled on two or more uplink, UL, physical channels, and the parallel transmissions comprise one or more sTTI transmissions.  FIGS. 2, 3, and 4  illustrate examples in which the wireless device  110  has scheduled parallel transmissions on a first UL physical channel (e.g., the channel on carrier  0 ) and a second UL physical channel (e.g., the channel on carrier  1 ), and the parallel transmissions in subframe (n) include sTTI transmissions. The embodiments in  FIGS. 2-4  show transmissions with the shorter transmission time intervals scheduled on a different carrier (carrier  1 ) than the transmissions with the longer transmission time intervals (carrier  0 ). 
     At action  1208 , the method determines whether the wireless device  110  has a limited amount of UL power for the parallel transmissions scheduled during the subframe. In response to determining that wireless device  110  is not power-limited during the subframe, the method may perform UL power allocation without having to prioritize the allocation of UL power among the parallel transmissions. Alternatively, in response to determining that wireless device  110  is power-limited during the subframe, the method proceeds to action  1212  to distribute UL power according to prioritization rules for parallel transmission scenarios that include sTTI transmissions. 
     At action  1212 , the method distributes UL power among the parallel transmissions. The UL power is distributed according to one or more prioritization rules. In certain embodiments, one of the prioritization rules may prioritize sTTI transmissions comprising control information over sTTI transmissions comprising data without any control information. Examples of methods that prioritize sTTI transmissions comprising control information over sTTI transmissions comprising data without any control information are discussed above with respect to power prioritization among UL physical channels of short TTI and  FIG. 5 . In certain embodiments, the prioritization rules for distributing UL power among the parallel transmissions comprise prioritizing the sTTI transmissions in the following order: (1) sTTI transmissions that use a control channel to transmit control information (such as sPUCCH), (2) sTTI transmissions that use a data channel to transmit control information (such as sPUSCH with UCI), and (3) sTTI transmissions that use the data channel to transmit data without any control information (such as sPUSCH without UCI). 
     In certain embodiments, one of the prioritization rules may prioritize transmissions with shorter transmission time intervals over transmissions with longer transmission time intervals. Examples of methods that prioritize transmissions with shorter transmission time intervals over transmissions with longer transmission time intervals are discussed above with respect to power prioritization between UL physical channels of short TTI and 1 ms TTI and  FIG. 6 , and certain examples can be summarized as follows:
         In certain embodiments, the parallel transmissions comprise both TTI and sTTI transmissions. Each TTI transmission has a duration of 1 ms, and each sTTI transmission has a duration of less than 1 ms. The prioritization rules for distributing the UL power among the parallel transmissions prioritize the sTTI transmission(s) over the TTI transmission(s).   In certain embodiments, each TTI transmission can be configured according to Long Term Evolution, LTE, Release 8 (e.g., 14 symbols in the case of normal CP or 12 symbols in the case of extended CP), each sTTi transmission can have a shorter duration than each TTI transmission (e.g., 2 symbols, 7 symbols, or other suitable value less than TTI), and the prioritization rules for distributing the UL power among the parallel transmissions prioritize the one or more sTTI transmissions over the one or more TTI transmissions.   In certain embodiments, the parallel transmissions comprise sTTI transmissions having different durations, such as a first sTTI transmission comprising 2 symbols and a second sTTI transmission comprising 7 symbols. Thus, the first sTTI has a shorter duration than the second sTTI. The prioritization rule for distributing UL power prioritizes the shorter sTTI (first sTTI having 2 symbols) over the longer sTTI (second sTTI having 7 symbols).       

     In certain embodiments, the prioritization rules can combine rules that prioritize distribution of UL power based on content of the transmission (e.g., prioritizing transmissions with control information over transmissions without control information) with rules that prioritize distribution of UL power based on duration of the transmission (e.g., prioritizing shorter transmissions over longer transmissions). For example, the prioritization rules for distributing UL power may prioritize transmissions in the following order: (1) sTTI transmissions that include control information, (2) sTTI transmissions that do not include control information, (3) TTI transmissions that include control information, (4) TTI transmissions that do not include control information. 
     At action  1216 , the method transmits the parallel transmissions according to the distribution of UL power determined in action  1212 . The method then ends. 
     The prioritization rules for distributing UL power discussed with respect to  FIG. 12  can calculate the UL power in any suitable manner. For example, as discussed above, one of the prioritization rules prioritizes transmissions in the following order: (1) sTTI transmissions that use a control channel to transmit control information (such as sPUCCH), (2) sTTI transmissions that use a data channel to transmit control information (such as sPUSCH with UCI), and (3) sTTI transmissions that use the data channel to transmit data without any control information (such as sPUSCH without UCI). In certain embodiments, calculating the UL power based on this rule may comprise the following actions:
         Reserve a first amount of UL power for the one or more sTTI transmissions scheduled on the control channel.   Calculate a first amount of remaining UL power by deducting the reserved first amount of UL power from a total UL power allowed or available to the wireless device.   Reserve a second amount of UL power from the first amount of remaining UL power, the second amount of UL power reserved for the one or more sTTI transmissions scheduled on the data channel and including the control information.   Calculate a second amount of remaining UL power by deducting the reserved second amount of UL power from the calculated first amount of remaining UL power.   Reserve a third amount of UL power from the second amount of remaining UL power, the third amount of UL power reserved for the one or more sTTI transmissions scheduled on the data channel and not including the control information.
 
Additionally, certain embodiments use a common factor to scale the UL power for the sTTI transmissions that use the data channel to transmit data (such as the sPUSCH without UCI) based on determining that the UL power is not sufficient for the parallel transmissions.
       

     As another example, one of the prioritization rules discussed above prioritizes sTTI transmissions over TTI transmissions. In certain embodiments, calculating the UL power based on this rule may comprise determining that the one or more sTTI transmissions are scheduled only at the beginning of the subframe. In this case, distributing the UL power for the subframe may comprise distributing a first amount of UL power for the one or more sTTI transmissions, calculating a remaining UL power by deducting the first amount of UL power from a total UL power allowed or available to the wireless device, and distributing the remaining UL power for the TTI transmissions. In the example, the first amount of UL power (the UL power for the one or more sTTI transmission) satisfies the UL power needed for the one or more sTTI transmissions.  FIG. 2  illustrates an example of distributing UL power to sTTI transmissions when the sTTI subframes are scheduled only at the beginning of the subframe (see subframe n of  FIG. 2 ). 
     In certain embodiments, each of the one or more sTTI transmissions is scheduled in the middle of the subframe. As discussed above with respect to  FIGS. 3-4 , in certain embodiments, distributing the UL power for the subframe comprises determining all of the UL transmissions that have been scheduled for the subframe as of a pre-determined time (t 0 ). The pre-determined time is based on an amount of time before the start of the subframe (t start -Δ). A first amount of UL power is distributed for the sTTI transmissions. The first amount of UL power satisfies the UL power needed for the one or more sTTI transmissions that have been scheduled for the subframe as of the pre-determined time (t 0 ) is distributed for the sTTI transmissions. The remaining UL power is calculated by deducting the first amount of UL power from a total UL power allowed or available to the wireless device. The remaining UL power is distributed for the TTI transmissions. 
     In certain embodiments, it may be determined that at least one of the one or more sTTI transmissions in the subframe did not get scheduled until after the pre-determined time (t 0 ). In that case, the UL power available for the TTI transmissions can be re-distributed during transmission of the sTTI(s) that did not get scheduled until after the pre-determined time (t 0 ). An example is shown in  FIG. 4 , scenario B, wherein during the time that the fourth sTTI is transmitted on carrier  1 , the UL power for the TTI on carrier  0  is reduced (in scenario B, UL power calculation for 1 ms TTI considers future scheduled sTTI). 
     In certain embodiments, less UL power is distributed to the TTI transmissions for a portion of the subframe during which the sTTI transmissions have been scheduled, and more UL power is distributed to the TTI for a portion of the subframe during which the sTTI transmissions have not been scheduled. Examples are shown in  FIG. 2  (carrier  0 , subframe n+1) and  FIG. 4  (carrier  0 , subframe n). 
     Summary of Example Embodiments 
     According to one example embodiment, a method in a user equipment is disclosed. The method comprises determining that the UE has parallel transmissions scheduled on two or more uplink (UL) physical channels, the parallel transmissions comprising short transmission time interval (sTTI) transmissions. The method comprises distributing UL power among the parallel transmissions scheduled on the two or more UL physical channels such that sTTI transmissions containing control information are prioritized over sTTI transmissions containing data. In certain embodiments, one or more of the following may apply:
         the method may comprise determining that the UE has limited UL power for the parallel transmissions scheduled on the two or more UL physical channels;   distributing UL power among the parallel transmissions scheduled on the two or more UL physical channels such that sTTI transmissions containing control information are prioritized over sTTI transmissions containing data may comprise:
           determining whether the UE has one or more UL transmissions scheduled on a control channel;   upon determining that the UE has one or more UL transmissions scheduled on a control channel, reserving a first amount of UL power for the one or more UL transmissions scheduled on the control channel;   calculating a first amount of remaining UL power by deducting the reserved first amount of UL power from a total available or total allowed UL power of the UE;   determining whether the UE has one or more UL transmissions scheduled on a data channel that include UL control information;   upon determining that the UE has one or more UL transmissions scheduled on a data channel that include UL control information, reserving a second amount of UL power from the first amount of remaining UL power for the one or more UL transmissions scheduled on the data channel that include UL control information;   calculating a second amount of remaining UL power by deducting the reserved second amount of UL power from the calculated first amount of remaining UL power;   determining whether the UE has one or more UL transmissions scheduled on a data channel that do not include UL control information; and   upon determining that the UE has one or more UL transmissions scheduled on the data channel that do not include UL control information, dedicating the second amount of remaining power to the one or more UL transmissions scheduled on the data channel that do not include UL control information;   
           the method may comprise:
           determining that the UL power as distributed is not sufficient for the parallel transmissions scheduled on the two or more UL physical channels; and   scaling the distributed power for the parallel transmissions using a common factor; and   
           the parallel transmissions may further comprise one or more 1 ms TTI UL transmissions, and the method may comprise:
           calculating an amount of UL power remaining after distributing UL power among the parallel transmissions scheduled on the two or more UL physical channels such that sTTI transmissions containing control information are prioritized over sTTI transmissions containing data; and   distributing the amount of UL power remaining such that 1 ms TTI transmissions containing control information are prioritized over 1 ms TTI transmissions that do not contain control information.   
               

     According to another example embodiment, a user equipment is disclosed. The user equipment comprises one or more processors. The one or more processors are configured to determine that the UE has parallel transmissions scheduled on two or more uplink (UL) physical channels, the parallel transmissions comprising short transmission time interval (sTTI) transmissions. The one or more processors are configured to distribute UL power among the parallel transmissions scheduled on the two or more UL physical channels such that sTTI transmissions containing control information are prioritized over sTTI transmissions containing data. 
     According to another example embodiment, a method in a user equipment is disclosed. The method comprises determining, before the start of a first subframe, an amount of power needed for one or more uplink (UL) transmissions scheduled in the first subframe, the one or more UL transmissions scheduled in the first subframe comprising at least one of an UL transmission having a transmission time interval (TTI) of 1 ms and an UL transmission having a short TTI. The method comprises setting a first power level for the UL transmission having the TTI of 1 ms based on the UL transmission having the short TTI scheduled in the first subframe. The method comprises transmitting the one or more UL transmissions having the TTI of 1 ms at the set first power level. In certain embodiments, one or more of the following may apply:
         the method may comprise determining all UL transmissions scheduled in the first subframe; and   the method may comprise determining that the UE has limited UL power for the parallel transmissions scheduled on the two or more UL physical channels.       

     According to another example embodiment, a user equipment is disclosed. The user equipment comprises one or more processors. The one or more processors are configured to determine, before the start of a first subframe, an amount of power needed for one or more uplink (UL) transmissions scheduled in the first subframe, the one or more UL transmissions scheduled in the first subframe comprising at least one of an UL transmission having a transmission time interval (TTI) of 1 ms and an UL transmission having a short TTI. The one or more processors are configured to set a first power level for the UL transmission having the TTI of 1 ms based on the UL transmission having the short TTI scheduled in the first subframe. The one or more processors are configured to transmit the one or more UL transmissions having the TTI of 1 ms at the set first power level. 
     Certain embodiments of the present disclosure may provide one or more technical advantages. For example, certain embodiments may advantageously enable a UE to distribute its power with the most appropriate priority in case the UE has not enough power for all UL physical channels. Other advantages may be readily apparent to one having skill in the art. Certain embodiments may have none, some, or all of the recited advantages. 
     Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
     Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other actions. Additionally, actions may be performed in any suitable order. 
     Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure, as defined by the following claims. 
     Abbreviations used in the Preceding Description include: 
     AP Access Point 
     BLER Block Error Rate 
     BS Base Station 
     BSC Base Station Controller 
     BTS Base Transceiver Station 
     CDM Code Division Multiplexing 
     CPE Customer Premises Equipment 
     D2D Device-to-device 
     DAS Distributed Antenna System 
     DCI Downlink Control Information 
     DFT Discrete Fourier Transform 
     DL Downlink 
     eNB evolved Node B 
     ePDCCH Enhanced Physical Downlink Control Channel 
     FDD Frequency Division Duplex 
     LAN Local Area Network 
     LEE Laptop Embedded Equipment 
     LME Laptop Mounted Equipment 
     LTE Long Term Evolution 
     M2M Machine-to-Machine 
     MAC Medium Access Control 
     MAN Metropolitan Area Network 
     MCE Multi-cell/multicast Coordination Entity 
     MCS Modulation and Coding scheme 
     MSR Multi-standard Radio 
     NAS Non-Access Stratum 
     OFDM Orthogonal Frequency Division Multiplexing 
     OFDMA Orthogonal Frequency Division Multiple Access 
     PDCCH Physical Downlink Control Channel 
     PDSCH Physical Downlink Shared Channel 
     PRB Physical Resource Block 
     PSTN Public Switched Telephone Network 
     PUSCH Physical Uplink Shared Channel 
     PUCCH Physical Uplink Control Channel 
     RB Resource Block 
     RE Resource Element 
     RNC Radio Network Controller 
     RRC Radio Resource Control 
     RRH Remote Radio Head 
     RRU Remote Radio Unit 
     SC-FDMA Single Carrier-Frequency Division Multiple Access 
     sPDCCH Short Physical Downlink Control Channel 
     sPDSCH Short Physical Downlink Shared Channel 
     sPUSCH Short Physical Uplink Shared Channel 
     sTTI Short Transmission Time Interval 
     TDD Time Division Duplex 
     TFRE Time Frequency Resource Element 
     TTI Transmission Time Interval 
     UCI Uplink Control Information 
     UE User Equipment 
     UL Uplink 
     WAN Wide Area Network