US20210160789A1

US20210160789A1 - Systems And Methods Of Performing Power Control Of A Physical Channel In A Communication System

Info

Publication number: US20210160789A1
Application number: US17/169,071
Authority: US
Inventors: Gustav Almquist; Mattias Andersson; Laetitia Falconetti; Daniel Chen Larsson
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2016-09-30
Filing date: 2021-02-05
Publication date: 2021-05-27
Also published as: JP2019533936A; CN114554578A; PL3520504T3; ES2946976T3; MA45364B1; BR112019006306A2; EP3520504B1; US20190215775A1; JP7174018B2; US10506528B2; RU2713728C1; CN110050488B; KR102247421B1; MA45364A1; WO2018060172A1; CN110050488A; JP2020205589A; EP3520504A1; JP6740469B2; KR20190040065A

Abstract

Systems and methods for performing power control of a physical channel in a communication system are provided. In one exemplary embodiment, a method in a wireless device of performing power control of a physical channel in a wireless communication system may include determining a transmission power for a transmission on the physical channel according to a power control loop. Further, the loop may specify the transmission power based on at least one parameter. Also, a value of the at least one parameter may be dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel.

Description

RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 16/328,808 filed Feb. 27, 2019, which is a national stage application of PCT/EP2017/074318 filed Sep. 26, 2017, and claims benefit of U.S. Provisional Application No. 62/402,819 filed Sep. 30, 2016, the disclosures of each of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to the field of communications, and in particular to performing power control of a physical channel in a communication system.

BACKGROUND

Packet data latency is one of the performance metrics that vendors, operators and end-users (e.g., via speed test applications) regularly measure. Latency measurements are performed in all phases of the lifetime of a radio access network system such as when verifying a new software release or system component, when deploying a system and when the system is in commercial operation.
One performance metric that guided the design of Long Term Evolution (LTE) was to provide shorter latencies than previous generations of 3GPP radio access technologies (RATs). By doing so, LTE is recognized by end users as providing faster access to the Internet and shorter data latencies than these previous generations. Packet data latency is important not only for the perceived responsiveness of the system but also indirectly influences the throughput of the system. HTTP/TCP is the dominating application and transport layer protocol used on the Internet. According to HTTP Archive (http://httparchive.org/trends.php), the typical size of HTTP based transactions over the Internet range from tens of kilobytes to one megabyte. In this 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 limited by latency. Hence, the average throughput can be improved by reducing the latency for this type of TCP based data transactions.
Furthermore, radio resource efficiency can be improved by reducing latency. For instance, lower packet data latency could increase the number of transmissions that are possible within a certain delay bound. Hence, higher Block Error Rate (BLER) targets could be used for data transmissions, resulting in freeing up radio resources to improve the capacity of the system.
Another area to reduce packet latency is to reduce the transport time of data and the associated control signaling. For instance, in LTE Release 8, a transmission time interval (TTI) corresponds to one subframe of length (i.e., 1 millisecond). One such TTI is constructed using fourteen orthogonal frequency division multiplexing (OFDM) or single-carrier, frequency-division multiple access (SC-FDMA) symbols in the case of normal cyclic prefix (CP) and twelve OFDM or SC-FDMA symbols in the case of extended CP. For LTE Release 13, shorter Ills (i.e., shorter than the LTE release 8 TTI) are being investigated. These shorter Ills may be any duration in time and may include resources on a number of OFDM or SC-FDMA symbols that are within the LTE Release 8 TTI (i.e., 1 millisecond). For instance, the duration of a short TTI may be 0.5 milliseconds (i.e., 7 OFDM or SC-FDMA symbols for normal CP) or may be 2 symbols. Accordingly, there is a need for improved techniques to perform power control of a physical channel in a communication system such as for a transmission on a physical channel having a short TTI. In addition, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and embodiments, taken in conjunction with the accompanying figures and the foregoing technical field and background.
The Background section of this document is provided to place embodiments of the present disclosure in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.

SUMMARY

The following presents a simplified summary of the disclosure in order to provide a basic understanding to those of skill in the art. This summary is not an extensive overview of the disclosure and is not intended to identify key/critical elements of embodiments of the disclosure or to delineate the scope of the disclosure. The sole purpose of this summary is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.
Briefly described, embodiments of the present disclosure relate to performing power control of a physical channel in a communication system. According to one aspect, a method in a wireless device of performing power control of a physical channel in a wireless communication system may include determining a transmission power for a transmission on the physical channel according to a power control loop, wherein the loop specifies the transmission power based on at least one parameter. Further, a value of the at least one parameter may be dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel.
According to another aspect, each TTI length usable on the physical channel may be based on a different value for the at least one parameter.
According to another aspect, the value of the at least one parameter may further depend on which of different transmission formats defined as usable on the physical channel is selected for the transmission on the physical channel.
According to another aspect, each transmission format usable on the physical channel may be based on a different value for the at least one parameter.
According to another aspect, the at least one parameter has a different value for each TTI length usable on the physical channel.
According to another aspect, the at least one parameter has a different value for each transmission format usable on the physical channel.
According to another aspect, the value of the at least one parameter may be based on a power adjustment for the transmission on the physical channel having the selected TTI length.
According to another aspect, the value of the at least one parameter may be based on a ratio of a power adjustment for the transmission on the physical channel having the selected TTI length and a power adjustment for the transmission on the physical channel having a predetermined TTI length.
According to another aspect, the value of the at least one parameter may be based on a number of symbols in the transmission on the physical channel having the selected TTI length.
According to another aspect, the value of the at least one parameter may be based on a ratio of a number of symbols in a transmission on the physical channel having the selected TTI length and a number of symbols in a transmission on the physical channel having a predetermined TTI length.
According to another aspect, the ratio may be represented as follows:
$1 0 \log_{1 0} (\frac{{TTIsymbols}_{selected}}{{TTIsymbols}_{predetermined}}),$

- wherein TTIsymbols_selectedis the selected number of TTI symbols, and TTIsymbols_{predetermined}is the predetermined number of TTI symbols.

According to another aspect, the ratio is further represented as follows:
$a 1 0 \log_{1 0} (\frac{{TTIpilotsymbols}_{selected}}{{TTIpilotsymbols}_{predetermined}}) + b 10 \log_{1 0} (\frac{{TTIcontrolsymbols}_{selected}}{{TTIcontrolsymbols}_{predetermined}})$

- wherein the selected number of TTI symbols corresponds to a selected number of pilot symbols (TTIpilotsymbols_selected) and a selected number of control symbols (TTIcontrolsymbols_selected), and the predetermined number of TTI symbols corresponds to a predetermined number of pilot symbols (TTIpilotsymbols_{predetermined}) and a predetermined number of control symbols (TTIcontrolsymbols_{predetermined}).

According to another aspect, the predetermined number of pilot symbols is six (6) and the predetermined number of control symbols is eight (8).
According to another aspect, the predetermined number of TTI symbols is fourteen (14).
According to another aspect, the value of the at least one parameter is based on a ratio of the selected TTI length and a predetermined TTI length.
According to another aspect, the ratio is represented as follows:
$1 0 \log_{1 0} (\frac{{TTIlength}_{selected}}{{TTIlength}_{predetermined}}),$

- wherein TTIlength_selectedis the selected TTI length, and TTIlength_{predetermined}is the predetermined TTI length.

According to another aspect, the ratio is further represented as follows:
$a 1 0 \log_{1 0} (\frac{{TTIpilotlength}_{selected}}{{TTIpilotlength}_{predetermined}}) + b 10 \log_{1 0} (\frac{{TTIcontrollength}_{selected}}{{TTIcontrollength}_{predetermined}}),$

- wherein the selected TTI length corresponds to a selected pilot symbols length (TTIpilotlength_selected) and a selected control symbols length (TTIcontrollength_selected). Further, the predetermined TTI length corresponds to a predetermined pilot symbols length (TTIpilotlength_{predetermined}) and a predetermined control symbols length (TTIcontrollength_{predetermined}). Also, a and bare constants.

According to another aspect, the predetermined TTI length is one millisecond.
According to another aspect, the value of the at least one parameter is based on a predetermined received power for the physical channel having the selected TTI length.
According to another aspect, the value of the at least one parameter is based on an adjustment that depends on whether frequency hopping is used for the transmission on the physical layer having the selected TTI length.
According to another aspect, the physical channel is a control channel.
According to another aspect, the physical channel is an uplink channel.
According to another aspect, a wireless device for performing power control of physical channels in a wireless communication system may be configured to determine a transmission power for a transmission on the physical channel according to a power control loop. The loop may specify the transmission power based on at least one parameter. Further, a value of the at least one parameter may be dependent on which of different TTI lengths defined as usable on the physical channel is selected for the transmission on the physical channel.
According to another aspect, a wireless device for performing power control of physical channels in a wireless communication system may include a processor and a memory. Further, the memory contains instructions executable by the processor whereby the wireless device may be configured to determine a transmission power for a transmission on the physical channel according to a power control loop. The loop may specify the transmission power based on at least one parameter. Also, a value of the at least one parameter being dependent on which of different TTI lengths defined as usable on the physical channel is selected for the transmission on the physical channel.
According to another aspect, a wireless device for performing power control of physical channels in a wireless communication system, comprises a processor and a memory. The memory containing instructions executable by the processor whereby the wireless device is configured to determine a transmission power for a transmission on the physical channel according to a power control loop, wherein the loop specifies the transmission power based on at least one parameter, with a value of the at least one parameter being dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel.
According to another aspect, the value of the at least one parameter further depends on which of different transmission formats defined as usable on the physical channel is selected for the transmission on the physical channel.
According to another aspect, the value of the at least one parameter is based on a number of symbols in the transmission on the physical channel having the selected TTI length.
According to another aspect, a method in a wireless device for performing power control of physical channels in a wireless communication system, comprises receiving, by the wireless device, from a network node an indication of a value of at least one parameter which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel. A transmission power for a transmission on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.
According to another aspect, a method in a network node for performing power control of physical channels in a wireless communication system, comprising: transmitting, by the network node, to a wireless device an indication of a value of at least one parameter which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel. A transmission power for a transmission by the wireless device on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.
According to another aspect, a network node for performing power control of physical channels in a wireless communication system, the network node configured to:
transmit, to a wireless device, an indication of a value of at least one parameter which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel. A transmission power for a transmission by the wireless device on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.
According to another aspect, a network node for performing power control of physical channels in a wireless communication system comprises a processor and a memory, the memory containing instructions executable by the processor whereby the network node is configured to transmit, to a wireless device, a value of at least one parameter which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel, wherein a transmission power for a transmission by the wireless device on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.
According to another aspect, a computer program product may be stored in a non-transitory computer readable medium for controlling a wireless device in a communication system. Further, the computer program product includes software instructions which, when run on the wireless device, may cause the wireless device to determine a transmission power for a transmission on the physical channel according to a power control loop. The loop may specify the transmission power based on at least one parameter. Also, a value of the at least one parameter may be dependent on which of different TTI lengths defined as usable on the physical channel is selected for the transmission on the physical channel. In addition, a carrier may contain the computer program. The carrier may be one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure are shown. However, this disclosure should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout.

FIG. 1 illustrates one embodiment of a system for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 2 illustrates one embodiment of a wireless device for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 3 illustrates another embodiment of a wireless device for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 4 illustrates another embodiment of a wireless device for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 5 illustrates one embodiment of method for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 6 illustrates another embodiment of a wireless device for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 7 illustrates another embodiment of method by a wireless device for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 8 illustrates one embodiment of a network node for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 9 illustrates another embodiment of a network node for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 10 illustrates another embodiment of a network node for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 11 illustrates one embodiment of method by a network node for performing power control of a physical channel in accordance with various aspects as described herein.

FIG. 12 illustrates an example where uplink sills are scheduled and closed loop power control (f_c(i)) is updated before the one millisecond uplink transmission is performed.

FIG. 13 illustrates a 20 usec. transient period between messages for sTTI.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an exemplary embodiment thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be readily apparent to one of ordinary skill in the art that the present disclosure may be practiced without limitation to these specific details. In this description, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure.
This disclosure includes describing systems and methods for performing power control of a physical channel in a communication system. For example, FIG. 1 illustrates one embodiment of a system 100 for performing power control of a physical channel in accordance with various aspects as described herein. In FIG. 1, the system 100 may include a network node 101 with coverage area 103, and a wireless device 105. Each of the network node 101 and the wireless device 105 may send different signals to the other. In one example, the network node 101 may transmit the signal 107 to the wireless device 105. In another example, the wireless device 105 may transmit the signal 107 to the network node 101. The signal 107 may include a series of transmissions 123 a-d on a physical channel 121. Further, these transmissions may have a certain transmission time interval (TTI) length 125. The wireless device 105 may determine a transmission power for each transmission on the physical channel 121 having the certain TTI length 125 according to a power control loop. The power control loop may specify the transmission power based on at least one parameter 111. Further, a value of the at least one parameter 111 may be dependent on which of different TTI lengths defined as usable on the physical channel 121 is selected for the transmission 123 a-d. A TTI length may be defined as usable if the wireless device is able to transmit at that TTI, e.g. according to a configuration or capability of the wireless device. Examples may of the disclosure may be defined without reference to TTI lengths being defined as usable.
The signal 107 may include a series of transmissions 123 a-d on a physical channel 121 (e.g., sPUCCH) and a series of transmission 123 a-d on the physical channel 121 (e.g., PUCCH) having a different TTI. An sPUCCH may be referred to as a short or shortened PUCCH, a slot PUCCH for 0.5 ms PUCCH, a subslot PUCCH for 1 ms/6 PUCCH, or the like. In one definition, an sPUCCH may refer to a PUCCH having a transmission time interval (TTI) that is less than a TTI of a normal PUCCH (e.g., LTE Release 8 PUCCH). For instance, a normal PUCCH has a TTI of one millisecond and an sPUCCH has a TTI of 0.5 milliseconds. In another definition, an sPUCCH may have a TTI that is less than one millisecond or less than 0.5 milliseconds. The transmitted signal 107 from the wireless device may be considered as an uplink channel and/or a control channel (e.g. PUCCH or sPUCCH).
Aspects of the disclosure may provide a method in a wireless device of performing power control of a physical channel in a wireless communication system. The wireless device 105 may determine a transmission power for a transmission on the physical channel (e.g. PUCCH or sPUCCH according to a power control loop. The loop specifies the transmission power based on at least one parameter. A value of the at least one parameter is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel. The value of the parameter may be dependent on the TTI length (e.g. 1 ms or a short TTI length of less than 1 ms) of the transmission and/or a format of the transmission. The value of the parameter may be determined by the wireless device e.g. based on configuration information received from the network node, and/or an indication of the value or information allowing a determination of the value of the parameter which is signalled to the wireless device. Any option for communicating a value of the parameter may be referred to as transmitting/receiving an indication of the value.
One such 1 ms TTI is constructed by using 14 OFDM or SC-FDMA symbols in the case of normal cyclic prefix and 12 OFDM or SC-FDMA symbols in the case of extended cyclic prefix. The shorter His may 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 may be 0.5 ms, i.e. seven OFDM or SC-FDMA symbols, e.g. for the case with normal cyclic prefix. As another example, the duration of the short TTI may be 2 symbols, 3 symbols, etc, or a combination of different short TTI lengths.
In one definition, a power control loop allows a wireless device to set its transmit output power to a certain value. A power control loop includes at least one of a closed power control loop and an open power control loop. An open power control loop allows a wireless device to set its transmit output power to a certain value when the wireless device is accessing a wireless communications network. A closed power control loop allows a wireless device to set its transmit output power to a certain value based on a transmit power control command received from a network node.
In FIG. 1, the network node 101 may be configured to support one or more communication systems such as LTE, UMTS, GSM, NB-IoT, the like, or any combination thereof. Further, the network node 101 may be a base station, an access point, or the like. The network node 101 may serve wireless device 105. The wireless device 105 may be configured to support one or more communication systems such as LTE, UMTS, GSM, NB-IoT, the like, or any combination thereof.
FIG. 2 illustrates one embodiment of a wireless device 200 for performing power control of a physical channel in accordance with various aspects as described herein. In FIG. 2, the wireless device 200 may include a transmission power determination circuit 201. The transmission power determination circuit 201 may be configured to determine a transmission power for a transmission on the physical channel according to a power control loop. The loop may specify the transmission power based on at least one parameter. Further, a value of the at least one parameter may be dependent on which of different TTI lengths defined as usable on the physical channel is selected for the transmission on the physical channel.
In some aspects, the wireless device comprises a receiver circuit configured to receive, from a network node such as one that is serving the wireless device 200, configuration information to allow determination of a value of the at least one parameter for one or more power control loops for the physical channel. The value may be dependent on the TTI, i.e. different for different transmission time interval lengths. In some aspects, the wireless device comprises a transmitter circuit configured to transmit, to the network node, on the physical channel using the determined transmission power for the power control loop.
FIG. 3 illustrates another embodiment of a wireless device 300 for performing power control of a physical channel in accordance with various aspects as described herein. In FIG. 3, the wireless device 300 may include processing circuit(s) 301, communications circuit(s) 305, antenna(s) 307, the like, or any combination thereof. The communication circuit(s) 305 may be configured to transmit or receive information to or from one or more network nodes or wireless devices via any communication technology. This communication may occur using the one or more antennas 307 that are either internal or external to the wireless device 300. The processing circuit(s) 301 may be configured to perform processing as described herein (e.g., the method of FIG. 5 or 7) such as by executing program instructions stored in memory 303. The processing circuit(s) 301 in this regard may implement certain functional means, units, or modules.
FIG. 4 illustrates another embodiment of a wireless device 400 for performing power control of a physical channel in accordance with various aspects as described herein. In FIG. 4, the wireless device 400 may implement various functional means, units, or modules (e.g., via the processing circuit(s) 301 in FIG. 3 or via software code). These functional means, units, or modules (e.g., for implementing the method of FIG. 5 or 7) may include a transmission power determining module 403 for determining a transmission power for a transmission on the physical channel according to a power control loop. The loop may specify the transmission power based on at least one parameter. Further, a value of the at least one parameter may be dependent on which of different TTI lengths defined as usable on the physical channel is selected for the transmission on the physical channel.
In some aspects, the wireless device 400 comprises functional means, units, or modules (e.g., for implementing the methods of FIGS. 5 and 7), including a receiving module or unit 401 for receiving, from a network node, configuration information or signalling to determine a value of at least one parameter for one or more loops for respective physical channels having different transmission time interval lengths. In addition, these functional means, units, or modules may include a transmitting module or unit for transmitting, to the network node, on the physical channel the determined transmission power for the power control loop.
FIG. 5 illustrates one embodiment of method 500 for performing power control of a physical channel in accordance with various aspects as described herein. In FIG. 5, the method 500 may start at, for instance, block 501 where it may determine a transmission power for a transmission on the physical channel according to a power control loop. Further, the loop may specify the transmission power based on at least one parameter. Also, a value of the at least one parameter being dependent on which of different TTI lengths defined as usable on the physical channel is selected for the transmission on the physical channel. In a further aspect, the method 500 may include transmitting, by the wireless device, to the network node, on the physical channel using the determined transmission power.
FIG. 6 illustrates another embodiment of a wireless device 600 for performing power control of a physical channel in accordance with various aspects as described herein. In some instances, the wireless device 600 may be referred as a network node, a base station (BS), an access point (AP), a user equipment (UE), a mobile station (MS), a terminal, a cellular phone, a cellular handset, a personal digital assistant (PDA), a smartphone, a wireless phone, an organizer, a handheld computer, a desktop computer, a laptop computer, a tablet computer, a set-top box, a television, an appliance, a game device, a medical device, a display device, a metering device, or some other like terminology. In other instances, the wireless device 600 may be a set of hardware components. In FIG. 6, the wireless device 600 may be configured to include a processor 601 that is operatively coupled to an input/output interface 605, a radio frequency (RF) interface 609, a network connection interface 611, a memory 615 including a random access memory (RAM) 617, a read only memory (ROM) 619, a storage medium 621 or the like, a communication subsystem 631, a power source 633, another component, or any combination thereof. The storage medium 621 may include an operating system 623, an application program 625, data 627, or the like. Specific devices may utilize all of the components shown in FIG. 6, or only a subset of the components, and levels of integration may vary from device to device. Further, specific devices may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc. For instance, a computing device may be configured to include a processor and a memory.
In FIG. 6, the processor 601 may be configured to process computer instructions and data. The processor 601 may be configured as any sequential state machine operative to execute machine instructions stored as machine-readable computer programs in the memory, such as one or more hardware-implemented state machines (e.g., in discrete logic, FPGA, ASIC, etc.); programmable logic together with appropriate firmware; one or more stored-program, general-purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processor 601 may include two computer processors. In one definition, data is information in a form suitable for use by a computer. It is important to note that a person having ordinary skill in the art will recognize that the subject matter of this disclosure may be implemented using various operating systems or combinations of operating systems.
In the current embodiment, the input/output interface 605 may be configured to provide a communication interface to an input device, output device, or input and output device. The wireless device 600 may be configured to use an output device via the input/output interface 605. A person of ordinary skill will recognize that an output device may use the same type of interface port as an input device. For example, a USB port may be used to provide input to and output from the wireless device 600. The output device may be a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. The wireless device 600 may be configured to use an input device via the input/output interface 605 to allow a user to capture information into the wireless device 600. The input device may include a mouse, a trackball, a directional pad, a trackpad, a presence-sensitive input device, a display such as a presence-sensitive display, a scroll wheel, a digital camera, a digital video camera, a web camera, a microphone, a sensor, a smartcard, and the like. The presence-sensitive input device may include a digital camera, a digital video camera, a web camera, a microphone, a sensor, or the like to sense input from a user. The presence-sensitive input device may be combined with the display to form a presence-sensitive display. Further, the presence-sensitive input device may be coupled to the processor. The sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, another like sensor, or any combination thereof. For example, the input device may be an accelerometer, a magnetometer, a digital camera, a microphone, and an optical sensor.
In FIG. 6, the RF interface 609 may be configured to provide a communication interface to RF components such as a transmitter, a receiver, and an antenna. The network connection interface 611 may be configured to provide a communication interface to a network 643 a. The network 643 a may encompass wired and wireless communication networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, the network 643 a may be a Wi-Fi network. The network connection interface 611 may be configured to include a receiver and a transmitter interface used to communicate with one or more other nodes over a communication network according to one or more communication protocols known in the art or that may be developed, such as Ethernet, TCP/IP, SONET, ATM, or the like. The network connection interface 611 may implement receiver and transmitter functionality appropriate to the communication network links (e.g., optical, electrical, and the like). The transmitter and receiver functions may share circuit components, software or firmware, or alternatively may be implemented separately.
In this embodiment, the RAM 617 may be configured to interface via the bus 602 to the processor 601 to provide storage or caching of data or computer instructions during the execution of software programs such as the operating system, application programs, and device drivers. In one example, the wireless device 600 may include at least one hundred and twenty-eight megabytes (128 Mbytes) of RAM. The ROM 619 may be configured to provide computer instructions or data to the processor 601. For example, the ROM 619 may be configured to be invariant low-level system code or data for basic system functions such as basic input and output (I/O), startup, or reception of keystrokes from a keyboard that are stored in a non-volatile memory. The storage medium 621 may be configured to include memory such as RAM, ROM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, flash drives. In one example, the storage medium 621 may be configured to include an operating system 623, an application program 625 such as a web browser application, a widget or gadget engine or another application, and a data file 627.
In FIG. 6, the processor 601 may be configured to communicate with a network 643 b using the communication subsystem 631. The network 643 a and the network 643 b may be the same network or networks or different network or networks. The communication subsystem 631 may be configured to include one or more transceivers used to communicate with the network 643 b. For example, the communication subsystem 631 may be configured to include one or more transceivers used to communicate with one or more remote transceivers of another wireless device such as a base station of a radio access network (RAN) according to one or more communication protocols known in the art or that may be developed, such as IEEE 802.xx, CDMA, WCDMA, GSM, LTE, UTRAN, WiMax, or the like.
In another example, the communication subsystem 631 may be configured to include one or more transceivers used to communicate with one or more remote transceivers of another wireless device such as user equipment according to one or more communication protocols known in the art or that may be developed, such as IEEE 802.xx, CDMA, WCDMA, GSM, LTE, UTRAN, WiMax, or the like. Each transceiver may include a transmitter 633 or a receiver 635 to implement transmitter or receiver functionality, respectively, appropriate to the RAN links (e.g., frequency allocations and the like). Further, the transmitter 633 and the receiver 635 of each transceiver may share circuit components, software or firmware, or alternatively may be implemented separately.
In the current embodiment, the communication functions of the communication subsystem 631 may include data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. For example, the communication subsystem 631 may include cellular communication, Wi-Fi communication, Bluetooth communication, and GPS communication. The network 643 b may encompass wired and wireless communication networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, the network 643 b may be a cellular network, a Wi-Fi network, and a near-field network. The power source 613 may be configured to provide an alternating current (AC) or direct current (DC) power to components of the wireless device 600.
In FIG. 6, the storage medium 621 may be configured to include a number of physical drive units, such as a redundant array of independent disks (RAID), a floppy disk drive, a flash memory, a USB flash drive, an external hard disk drive, thumb drive, pen drive, key drive, a high-density digital versatile disc (HD-DVD) optical disc drive, an internal hard disk drive, a Blu-Ray optical disc drive, a holographic digital data storage (HDDS) optical disc drive, an external mini-dual in-line memory module (DIMM) synchronous dynamic random access memory (SDRAM), an external micro-DIMM SDRAM, a smartcard memory such as a subscriber identity module or a removable user identity (SIM/RUIM) module, other memory, or any combination thereof. The storage medium 621 may allow the wireless device 600 to access computer-executable instructions, application programs or the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied in storage medium 621, which may comprise a computer-readable medium.
The functionality of the methods described herein may be implemented in one of the components of the wireless device 600 or partitioned across multiple components of the wireless device 600. Further, the functionality of the methods described herein may be implemented in any combination of hardware, software or firmware. In one example, the communication subsystem 631 may be configured to include any of the components described herein. Further, the processor 601 may be configured to communicate with any of such components over the bus 602. In another example, any of such components may be represented by program instructions stored in memory that when executed by the processor 601 performs the corresponding functions described herein. In another example, the functionality of any of such components may be partitioned between the processor 601 and the communication subsystem 631. In another example, the non-computative-intensive functions of any of such components may be implemented in software or firmware and the computative-intensive functions may be implemented in hardware.
FIG. 7 illustrates another embodiment of method 700 by a wireless device for performing power control of physical channels in accordance with various aspects as described herein. In FIG. 7, the method 700 may start, for instance, at block 701, where it includes receiving from a network node, a value of at least one parameter which is dependent on which of different transmission time interval lengths defined as usable on the physical channel is selected for the transmission on the physical channel. At block 703, the method 700 may include determining the transmission power for the physical channel based on the parameter. A transmission power for a transmission on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter. At block 705, the method 700 may include transmitting, to the network node, on the physical channel using the determined transmission power for the power control loop.
FIG. 8 illustrates one embodiment of a network node 800 for performing power control of physical channels (e.g. an uplink control channel) in accordance with various aspects as described herein. In FIG. 8, the network node 800 may include a receiver circuit 801, a determination circuit 803, a transmitter circuit 805, the like, or any combination thereof. The determination circuit 803 may be configured to determine a value of at least one parameter which is dependent on which of different transmission time interval lengths defined as usable on the physical channel is selected for the transmission on the physical channel. A transmission power for a transmission by the wireless device on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.
The transmitter circuit 805 is configured to transmit, to the wireless device, the value or an indication of the value or a configuration which provides the value, of the at least one parameter that corresponds to the transmission powers for the transmissions by the wireless device on the physical channel having the different transmission time interval lengths.
The receiver circuit 801 may be configured to receive, by the network node, transmissions by the wireless device on the physical channel with each transmission having a transmission power based on the one or more parameters according to the corresponding power control loop.
FIG. 9 illustrates another embodiment of a network node 900 for performing power control of physical channels in accordance with various aspects as described herein. In FIG. 9, the network node 900 may include processing circuit(s) 901, communications circuit(s) 905, antenna(s) 907, the like, or any combination thereof. The communication circuit(s) 905 may be configured to transmit or receive information to or from one or more network nodes or one or more wireless devices via any communication technology. This communication may occur using the one or more antennas 907 that are either internal or external to the network node 900. The processing circuit(s) 901 may be configured to perform processing as described herein (e.g., the method of FIG. 11) such as by executing program instructions stored in memory 903. The processing circuit(s) 901 in this regard may implement certain functional means, units, or modules.
FIG. 10 illustrates another embodiment of a network node 1000 for performing power control of physical channels in accordance with various aspects as described herein. In FIG. 10, the network node 1000 may implement various functional means, units, or modules (e.g., via the processing circuit(s) 901 in FIG. 9 or via software code). These functional means, units, or modules (e.g., for implementing the method of FIG. 11) may include a determining module or unit 1001 for determining a value of at least one parameter based on one or more received transmissions, from the wireless device, on the physical channel as described according to any example. Further, these functional means, units, or modules include a transmitting module or unit 1003 for transmitting, to the wireless device, the value of the at least one parameter that corresponds to the transmission powers for the transmissions by the wireless device on the physical channels having the different transmission time interval lengths according to respective power control loops. In addition, these functional means, units, or modules may include a receiving module or unit 1005 for receiving, from the wireless device, transmissions on each of the physical channels with each transmission having a transmission power based on the one or more parameters according to the corresponding power control loop.
FIG. 11 illustrates one embodiment of method 1100 performed by a network node for performing power control of physical channels in accordance with various aspects as described herein. In FIG. 11, the method 1100 may start, for instance, at block 1101 where it may include, in a network node in a wireless communication system, determining a value of at least one parameter which is dependent on which of different transmission time interval lengths defined as usable on the physical channel is selected for the transmission on the physical channel. A transmission power for a transmission by the wireless device on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.
At block 1103, the method 1100 includes transmitting, to the wireless device, the value or an indication of the value or a configuration which provides the value of the at least one parameter that corresponds to the transmission powers for the transmissions by the wireless device on the physical channels having the different transmission time interval lengths according to respective power control loops. At block 1105, the method 1100 may include receiving, from the wireless device, transmissions on the physical channel with the transmission having a transmission power based on the one or more parameters according to the power control loop including the determined parameter.
For purposes of illustration and explanation only, embodiments of the present disclosure may be described herein in the context of operating in or in association with a RAN that communicates over radio communication channels with wireless devices, also interchangeably referred to as mobile terminals, wireless terminals, UEs and the like, using a particular radio access technology. More specifically, embodiments may be described in the context of the development of specifications for NB-IoT, particularly as it relates to the development of specifications for NB-IoT operation in spectrum or using equipment currently used by E-UTRAN, sometimes referred to as the Evolved UMTS Terrestrial Radio Access Network and widely known as the LTE system. However, it will be appreciated that the techniques may be applied to other wireless networks, as well as to successors of the E-UTRAN. Thus, references herein to signals using terminology from the 3GPP standards for LTE should be understood to apply more generally to signals having similar characteristics or purposes, in other networks. For example, a physical resource block (PRB) herein comprises any physical or virtual transmission resource or group of such transmission resources; that is, a physical resource block as used herein is not limited to a physical resource block as defined in 3GPP standards.
A wireless device, as described herein, may be any type of wireless device capable of communicating with a network node or another wireless device (such as a user equipment, UE) over radio signals. In the context of the present disclosure, it should be understood that a wireless device may refer to a machine-to-machine (M2M) device, a machine-type communications (MTC) device, or an NB-IoT device. The wireless device may also be a UE, however it should be noted that the UE does not necessarily have a “user” in the sense of an individual person owning or operating the device. A wireless device may also be referred to as a radio device, a radio communication device, a wireless terminal, or simply a terminal unless the context indicates otherwise, the use of any of these terms is intended to include device-to-device UEs or devices, machine-type devices or devices capable of machine-to-machine communication, sensors equipped with a wireless device, wireless-enabled table computers, mobile terminals, smart phones, laptop-embedded equipped (LEE), laptop-mounted equipment (LME), USB dongles, wireless customer-premises equipment (CPE), etc. In the discussion that follows, the terms machine-to-machine (M2M) device, machine-type communication (MTC) device, wireless sensor, and sensor may also be used. It should be understood that these devices may be UEs, but are generally configured to transmit or receive data without direct human interaction.
In an IOT scenario, a wireless device as described herein may be, or may be comprised in, a machine or device that performs monitoring or measurements, and transmits the results of such monitoring measurements to another device or a network. Particular examples of such machines are power meters, industrial machinery, or home or personal appliances, e.g. refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a wireless device as described herein may be comprised in a vehicle and may perform monitoring or reporting of the vehicle's operational status or other functions associated with the vehicle.
PUCCH can be used to carry different types of information: e.g. HARQ feedback, scheduling requests (SR), CQI feedback. Different PUCCH formats with different maximum payloads are defined to be able to carry the different information types.
PUCCH format 1/1a/1b is suitable for transmitting HARQ feedback and scheduling requests (SR).
PUCCH format 2 is dedicated to the transmission of CQI reports. PUCCH format 3 supports the HARQ feedback for multiple carrier components when carrier aggregation is configured for a UE. It can be expected that different formats with different maximum payloads will be supported for sPUCCH.
Power control for PUCCH is defined in 3GPP TS 36.213 as, for subframe i and serving cell c,
$P_{PUCCH} (i) = \min {\begin{matrix} P_{CMAX, c} (i), \\ \begin{matrix} P_{0_{-} PUCCH} + P L_{c} + h (n_{CQI}, n_{HARQ}, n_{SR}) + \\ Δ_{F_PUCCH} (F) + Δ_{TxD} (F^{'}) + g (i) \end{matrix} \end{matrix}}$ $for PUCCH format 1 / 1 a / 1 b / 2 / 2 a / 2 b / 3 and$ $P_{PUCCH} (i) = \min {\begin{matrix} P_{CMAX, c} (i), \\ \begin{matrix} P_{0_{-} PUCCH} + P L_{c} + 10 \log_{10} (M_{PUCCH, c} (i)) + \\ Δ_{TF, c} (i) + Δ_{F_PUCCH} (F) + g (i) \end{matrix} \end{matrix}}$ $for PUCCH format 4 / 5,$
where

- P_CMAX,c(i) is the maximum transmit power.
- P_{O_PUCCH}is the target of received power.
- PL_cis 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 resource blocks 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_TF,c(i) is an adjustment factor depending on number of coded bits that is exactly specified in 3GPP TS36.213.
- Δ_TxD(F) depends on the number of antenna ports configured for PUCCH.
- g(i) is the closed loop power control state and is updated using δ_PUCCHsignalled in the downlink assignment.

Apparatus and method to support power control of an uplink control channel, in particular, sPUCCH transmissions are described below. These provide for power control to be achieved in a simple and efficient manner.
sPUCCH is the short TTI equivalent of PUCCH. In some examples, there will be at least one format of sPUCCH defined for each supported UL TTI length. Example UL TTI lengths are 2, 4 and 7 SC-FDMA symbols, although the TTI may contain other numbers of symbols. The formats selected for sPUCCH may be based on existing formats of PUCCH. Link level simulations performed highlight that independently of the selected sPUCCH format(s), a larger SNR is required for sPUCCH compared to PUCCH in order to reach similar performance e.g. in terms of ACK missed detection probability, NACK-to-ACK error probability and/or DTX-to-ACK probability. The shorter the sPUCCH length, the larger is the performance gap relative to PUCCH. The sPUCCH power control addresses this performance gap for UEs that are not power-limited. References to PUCCH or sPUCCH may alternatively be referred to as an uplink control channel.
The above closed loop power control equations may be applied to sPUCCH, with the modifications described below. The closed loop power control state, g(i), for PUCCH is derived from the Transmit Power Control, TPC, information δ_PUCCHsignalled to the wireless device 300;400, e.g. in the downlink assignment for 1 ms TTI. For fast closed loop power control of sPUCCH, δ_PUCCHmay also be signalled for sPUCCH in the downlink assignment for sTTI. The power control of transmissions according to the examples described may be carried out by a wireless device 105, 200, 300, 400, 600 according to any example. An indication of the value of one or parameter (which may be by providing configuration information) may be transmitted to the wireless device from a network node according to any example of network node 800;900;1000. The performance difference may be captured in Δ_{F_PUCCH}(F) that is signaled from higher layers. The performance difference is format-dependent and also TTI length dependent, and so in some examples, a complementary parameter is used. In addition to what is described below, h(n_CQI, n_HARQ, n_SR) and Δ_TF,c(i) are defined for sTTI formats and TTI lengths. The reference format for sPUCCH is proposed to be PUCCH format 1a. In the following, several options for sPUCCH power control are considered.
In some aspects, a method or wireless device are provided for determining a transmission power for a transmission on the physical channel according to a power control loop, wherein the loop specifies the transmission power based on at least one parameter. A value of the at least one parameter is dependent on which of different transmission time interval (TTI) lengths defined as usable (e.g. a short TTI) on the physical channel is selected for the transmission on the physical channel. In some examples, the at least one parameter has a different value for each TTI length usable on the physical channel. In some examples, the value of the at least one parameter further depends on which of different transmission formats defined as usable on the physical channel is selected for the transmission on the physical channel. In some examples, the at least one parameter has a different value for each transmission format usable on the physical channel.
In a first embodiment, a power control parameter Δ_{T_PUCCH}(F) is defined for the different formats and TTI lengths of sPUCCH. If the sPUCCH formats are defined as standalone formats and added to the current list of PUCCH formats existing today, then this provides an effective control of the desired transmission power of sPUCCH. The different TTI lengths of the sPUCCHs may be considered as part of the format. A new Δ_{T_PUCCH}(F) may be defined for each new format, i.e. for each new variant of selected legacy format types and TTI length.
In some example sTTI formats, frequency hopping is not used. In order to alleviate the loss of frequency diversity, a constant term can be added to the formats without frequency hopping.
In a further embodiment, a power control parameter Δ_{T_PUCCH}(F) is defined for the different formats of sPUCCH. A further, new, power control parameter depending on the TTI length is introduced and added to the other parameters in the power control formulas. In this example, the new sPUCCH formats may be defined as based on the legacy formats, but with different TTI lengths. This example may provide for more transparency for the case described above without frequency hopping.
In some aspects, a new value of the parameter Δ_{T_PUCCH}(F) would then be defined for each format type, e.g. each new variant of selected legacy format types, and this new Δ_{F_PUCCH}(F) is common to all short TTI lengths, e.g. shorter than the 1 ms TTI. Additionally, a new power control parameter Δ_TTI(TTIlength) is defined to refine the power adjustment for each possible TTI length. The power control parameter Δ_TTI(TTIlength) is included in the above power control equations with the instance of Δ_{F_PUCCH}(F). Note that this requires that a TTI length change affects the required power for all formats equally. One way of defining the parameters is that Δ_{T_PUCCH}(F) is defined by a given sTTI length. The parameter Δ_TTI(TTIlength), which has a value which is TTI length dependent, applies for all other sTTI lengths. In some aspects, Δ_TTI(TTIlength) may be a scaling factor depending on the sTTI length and is not a configurable parameter.
In some aspects, the value of the at least one parameter is based on a power adjustment for the transmission on the physical channel having the selected TTI length. Any of the parameters described may be considered as providing a power adjustment.
In some aspects, the value of the at least one parameter is based on a ratio of a power adjustment for the transmission on the physical channel having the selected TTI length (e.g. sTTI) and a power adjustment for the transmission on the physical channel having a predetermined TTI length (e.g. 1 ms TTI). Thus, the value of the parameter, which may be any parameter described, provides for the same power in sPUCCH for the sTTI as for the PUCCH for the 1 ms TTI. In any example, the selected TTI length may be a short TTI or a 1 ms TTI e.g. having 14 symbols.
In some aspects, the value any of the power control parameters is based on a number of symbols in the transmission on the physical channel having the selected TTI length (e.g. sTTI length). In some aspects, the value of the at least one parameter (power control parameter) is based on a ratio of a number of symbols in a transmission on the physical channel having the selected TTI length (sTTI) and a number of symbols in a transmission on the physical channel having a predetermined TTI length (1 ms TTI). In some aspects, the ratio, e.g. defining the parameter Δ_TTI(TTI length), is represented as:
$1 0 \log_{1 0} (\frac{{TTIsymbols}_{selected}}{{TTIsymbols}_{predetermined}}),$

- wherein TTIsymbols_selectedis the selected number of TTI symbols (e.g. sTTI), and TTIsymbols_{predetermined}is the predetermined number of TTI symbols (e.g. in 1 ms TTI). The parameter may alternatively be expressed in terms of length of time rather in terms of symbols

$as : 1 0 \log_{1 0} (\frac{{TTIlength}_{selected}}{{TTIlength}_{predetermined}}),$
wherein TTIlength_selectedis the selected TTI length, and TTIlength_{predetermined}is the predetermined TTI length.
In a version of this embodiment, length), Δ_TTI(TTI length)=10 log₁₀TTIlength/14. TTI length here is the number of symbols in the (s)TTI. This provides that the received energy (i.e. power) of the sPUCCH format is the same as for the legacy PUCCH format having 14 symbols.
In a further example, it is noted that some OFDM symbols in a PUCCH transmission are used for sending pilots, and others are used for sending Uplink Control Information, UCI. In some aspects, it might be beneficial to more closely compensate for the different energy requirements for channel estimation and decoding.
Therefore, a refinement of the above formula for a parameter, e.g. Δ_TTI(TTI length) may be (or include a ratio):
$a 10 \log_{1 0} (\frac{{TTIpilotsymbols}_{selected}}{{TTIpilotsymbols}_{predetermined}}) + b 10 \log_{1 0} (\frac{{TTIcontrolsymbols}_{selected}}{{TTIcontrolsymbols}_{predetermined}})$
wherein the selected number of TTI symbols corresponds to a selected number of pilot symbols (TTIpilotsymbols_selected) and a selected number of control symbols (TTIcontrolsymbols_selected), and the predetermined number of TTI symbols corresponds to a predetermined number of pilot symbols (TTIpilotsymbols_{predetermined}) and a predetermined number of control symbols (TTIcontrolsymbols_{predetermined}), wherein a and bare constants.
An equivalent for TTI length in time may be expressed as:
$a 10 \log_{1 0} (\frac{{TTIpilotlength}_{selected}}{{TTIpilotlength}_{predetermined}}) + b 10 \log_{1 0} (\frac{{TTIcontrollength}_{selected}}{{TTIcontrollength}_{predetermined}}),$
wherein the selected TTI length corresponds to a selected pilot symbols length (TTIpilotlength_selected) and a selected control symbols length (TTIcontrollength_selected), wherein the predetermined TTI length corresponds to a predetermined pilot symbols length (TTIpilotlength_{predetermined}) and a predetermined control symbols length (TTIcontrollength_{predetermined}), and wherein a and bare constants.
In some aspects, this expression may alternatively be defined as:
$Δ_{TTI} ({TTI}_{p} \cdot {TTI}_{UCI}) = a 10 \log_{10} \frac{{TTI}_{p}}{{Ref}_{p}} + b 10 \log_{10} \frac{{TTI}_{UCI}}{Ref_UCI},$
where Ref_UCI and Ref p are the number of OFDM symbols used for UCI and for pilots for a reference format, respectively. For example, if PUCCH Format 4 is the reference format, Ref p=2, and Ref UCI=12. The values a and b are constants that can be used to configure, or weight, the importance of channel estimation versus decoding performance. For PUCCH formats 1a/1b used for reference, Ref p=6, and Ref UCI=8.
In an embodiment, Δ_{F_PUCCH}(F) is defined for the different formats of sPUCCH. New vales of the target of received powers P_{O_PUCCH}are defined for the different TTI lengths. The new sPUCCH formats will have different target of received powers than the current PUCCH formats, primarily because of the different TTI lengths. This could be captured, or included, in new (i.e. modified) values of the power control parameter P_{O_PUCCH}for the sPUCCH formats. In some aspects, this may be used if the sPUCCH formats are defined in such a way that the target of received power differs substantially from the target of received power for 1 ms TTI (i.e. as used today). In some aspects, the same amount of new, i.e. modified, power control parameter Δ_{F_PUCCH}(F) may be defined as in the first embodiment above. In a variant of this embodiment, the same target of received power P_{O_PUCCH}is used for different sTTI lengths, and a TTI-length dependent received power offset P_{O_PUCCH_OFFSET}is added to the power control equation with the target of received power.
In an embodiment, even though the above alternatives are listed in separate embodiments, it is also an alternative to combine different embodiments to provide a solution. Note in particular that the embodiment including Δ_TTI(TTI length)=10 log₁₀TTIlength/14 above requires a reference format, and may fit well into a term which depends on the sPUCCH format.
In another embodiment, the techniques described herein may be applied for a transmission duration based on a two-symbol sTTI, four-symbol sTTI, and one-slot sTTI for sPUCCH/sPUSCH, where down-selection is not precluded.
In another embodiment, the techniques described herein may be applied for an LTE frame structure type 2, which specifies support for a transmission duration based on a one-slot sTTI for sPDSCH/sPDCCH/sPUSCH/sPUCCH.
A power control methodology for sPUSCH and sPUCCH for sTTI is described below. Power control for PUSCH for subframe i and serving cell C is defined as follows:
$P_{PUSCH, c} (i) = \min {\begin{matrix} 10 \log_{10} ({\hat{P}}_{CMAX, c} (i) - {\hat{P}}_{PUCCH} (i)), \\ \begin{matrix} 10 \log_{10} (M_{PUSCH, c} (i)) + P_{O_PUSCH, c} (j) + \\ α_{c} (j) \cdot {PL}_{c} + Δ_{TF, c} (i) + f_{c} (i) \end{matrix} \end{matrix}},$
where:
{circumflex over (P)}_CMAX,c(i) is the maximum transmit power in linear scale;
{circumflex over (P)}_PUCCH(i) is the power of simultaneously transmitted PUCCH in linear scale, is equal to zero if no PUCCH is transmitted;
M_PUSCH,c(i) is the number of resource blocks;
P_{O_PUSCH,c}(j) is the target of received power signaled to the UE over RRC;
α_c(j)·PL_cis the scaled downlink 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 number of coded bits; and
f_c(i) is the closed loop power control derived from what is signaled to the UE in the uplink grant.
Assuming a fixed allocated bandwidth for all TTI lengths and that the transport block size (TBS) is scaled linearly with the TTI length, a comparison of performance between PUSCH and sPUSCH indicates that 10% block error rate (BLER) is achieved at a similar signal-to-noise ratio (SNR) for sPUSCH and PUSCH. This means that using the same target received power level for sPUSCH as for PUSCH leads to similar sPUSCH and PUSCH performance.
Accordingly, PUSCH and sPUSCH have the same or similar performance assuming a fixed allocated bandwidth and a linearly scaled TBS with the TTI length. As a consequence, sPUSCH may be power controlled in the same way as PUSCH. The following equation shows how the power control for sPUSCH transmission in short TTI i would look like if a UE is not power limited. The power control parameters configured over RRC for PUSCH may be reused for sPUSCH. This means that the parameters P_{O_PUSCH,c}(j) and α_c(j) configured over RRC for PUSCH transmission are applied in the power control equation for sPUSCH according to:
P _sPUSCH,c(i)=10 log₁₀(M _sPUSCH,c(i))+P _{O_PUSCH,c}(j)+α_c(j)·PL _c+Δ_TF,c(i)+f _c(i).
Accordingly, sPUSCH should be power controlled in the same way as PUSCH, with the same parameters configured over RRC.
Regarding the closed loop parameter (f_c) that is calculated based on TPC information δ_PUSCHcontained in the uplink grant for one millisecond TTI, there may be a benefit to signal it in each uplink grant for sTTI so as to be able to faster correct the UE power and converge to the appropriate value. As such, TPC information used to update the closed loop component of the uplink power control (f_c) is included in the uplink grant of uplink sTTI.
Two methods exist today to calculate f_c: accumulation activated or not activated. If accumulation is not activated, f_c(i) follows directly the value of δ_PUSCHindicated in the uplink grant. This method may be easily extended for the case of sTTI. If accumulation is activated, f_c(i) is updated according to δ_PUSCHin the uplink 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_PUSCHrepresents the delay between the uplink grant and the uplink data transmission (transmission). With δ_PUSCHincluded in the uplink grant for sTTI, the accumulation happens more frequently than on a millisecond basis. Thus, the UE power converges faster to the intended value, which is beneficial.
Short TTI UEs may be scheduled dynamically with a subframe to subframe granularity with PUSCH and/or sPUSCH. Since the accumulation-based method makes f_c(i) dependent of its previous value f_c(i−1), it should be considered whether the calculation of f_c(i) for a one millisecond uplink TTI that follows immediately a uplink sTTI should be based on the f_cvalue used for this uplink sTTI and vice-versa. In other words, a one millisecond uplink TTI and uplink sTTI share the same parameter for the closed loop correction f_c.
Separate closed loop correction between different TTI lengths is an alternative. However, if the uplink power control equation of PUSCH is reused for sPUSCH with the same RRC configured parameters, there is no reason to have separate closed loop components f_cone valid for one millisecond TTI and another valid for short TTI. In fact, with a common closed loop component f_cfor both one millisecond uplink TTI and uplink sTTI, the power used for one millisecond TTI may benefit from the faster convergence of f_cto the most appropriate value due to uplink sTTI usage.
Accordingly, a shared closed loop component f_cis used for uplink power control of one millisecond TTI and sTTI. However, situations like the one depicted in FIG. 12 may happen where uplink grants for one or more uplink sills are sent after the uplink grant for a one millisecond TTI. Since the delay between the uplink grant for uplink sTTI and the uplink sTTI transmission is shorter than the one between the uplink grant for one millisecond TTI and the one millisecond uplink TTI transmission, the value for δ_PUSCHindicated in the uplink grant of one millisecond TTI becomes obsolete.
Consider the example in FIG. 12 with an initial value f_c,init, the command in the uplink grant for one millisecond TTI intends to achieve an uplink power corrected by f_c,init+3 dB. In the meantime, uplink sills are scheduled and δ_PUSCHis signaled in the uplink grant for sTTI as well. In this example, the first uplink sTTI transmission applies a closed loop component of f_c,init+3 dB. The eNB then observes that the correction of +3 dB was not accurate enough and sends a further correction in the uplink grant for the second uplink sTTI. The closed loop component for the second uplink sTTI is corrected to f_c,init+3 dB−1 dB. In this example, if the UE follows the δ_PUSCHsent in the uplink grant of the one millisecond TTI, the closed loop component would reach f_c,init+3 dB−1 dB+3 dB. Instead, it appears more reasonable that the UE ignores the old δ_PUSCHsent in the uplink grant of one millisecond TTI if δ_PUSCHcommands were received in uplink short TTI grants afterwards and if the calculation of f_c(i) is accumulation-based.
Accordingly, if the calculation of f_c(i) is accumulation-based, the UE ignores a δ_PUSCHsent in the uplink grant of one millisecond TTI if δ_PUSCHcommands were received in uplink short TTI grants afterwards.
Note that while the power control mechanism for PUSCH and sPUSCH are proposed to be the same, they both are indirectly affected by the introduction of sPUCCH power control since the meaning of {circumflex over (P)}_PUCCH(i) will change or a new parameter {circumflex over (P)}_sPUCCH(i) needs to be introduced with similar mechanism.
Power control for PUCCH formats 1/1a/1b/2/2a/2b/3 for subframe i and serving cell C is described as follows:
$P_{PUCCH} (i) = \min {\begin{matrix} P_{CMAX, c} (i), \\ \begin{matrix} P_{0_{-} PUCCH} + P L_{c} + h (n_{CQI}, n_{HARQ}, n_{SR}) + \\ Δ_{F_PUCCH} (F) + Δ_{TxD} (F^{'}) + g (i) \end{matrix} \end{matrix}},$
where:
P_CMAX,c(i) is the maximum transmit power;
P_{O_PUCCH}is the target of received power;
PL_cis 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 resource blocks for PUCCH format 5, equals one for all other formats;
Δ_{F_PUCCH}(F) is a relation in dB between PUCCH format F and PUCCH format 1a;
Δ_TF,c(i) is an adjustment fact or depending on number of coded bits;
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_PUCCHsignaled in the downlink assignment.
Power control for PUCCH formats 4/5 for subframe i and serving cell C is described as follows:
$P_{PUCCH} (i) = \min {\begin{matrix} P_{CMAX, c} (i), \\ \begin{matrix} P_{0_{-} PUCCH} + P L_{c} + 10 \log_{10} (M_{PUCCH, c} (i)) + \\ Δ_{TF, c} (i) + Δ_{F_PUCCH} (F) + g (i) \end{matrix} \end{matrix}} .$
There may be at least one format of sPUCCH defined for each supported uplink TTI length. The uplink TTI lengths may be any number of symbols. For instance, the uplink TTI lengths may be two, four, and seven SC-FDMA symbols. Independent of the selected sPUCCH format(s), a larger SNR may be required for sPUCCH compared to PUCCH in order to reach similar performance in terms of ACK missed detection probability, NACK-to-ACK error probability, DTX-to-ACK probability, and the like. The shorter sPUCCH is relative to PUCCH, the larger the performance gap between sPUCCH and PUCCH. So, the sPUCCH power control needs to address this performance gap for UEs that are not power-limited. The closed loop state (g(i)) for PUCCH is derived from the TPC information δ_PUCCHsignaled in the downlink assignment for one millisecond TTI. For fast closed loop power control of sPUCCH, it would be convenient to also signal δ_PUCCHfor sPUCCH in the downlink assignment for sTTI. A way to capture the performance difference in Δ_FiPUCCH(F) that is signaled from higher layers. However, since the performance difference is not only format-dependent but also TTI length dependent, a complementary parameter may be needed. In the following, several options for sPUCCH power control are considered.
In one embodiment, Δ_{F_PUCCH}(F) is defined for the different formats and TTI lengths of sPUCCH. If the new sPUCCH formats are defined as standalone formats and added to the current list of PUCCH formats existing today, then this is the straight forward approach to describe the desired power of sPUCCH. The different TTI lengths of the sPUCCHs may then simply be considered as part of the format. A new Δ_{F_PUCCH}(F) would then be defined for each new format (e.g., for each new variant of selected legacy format types and TTI length).
In another embodiment, Δ_{F_PUCCH}(F) is defined for the different formats of sPUCCH. A new parameter depending on the TTI length is introduced and added to the other parameters in the power control formulas. If the new sPUCCH formats are defined as based on the legacy formats, but with different TTI lengths, or if more transparency is desired, then this is a logical way forward. A new Δ_{F_PUCCH}(F) would then be defined for each new format (e.g., for each new variant of selected legacy format types). Additionally, a new parameter Δ_TTI(TTI−length) would need to be defined for each possible TTI length. Note that this requires that a TTI length change affects the required power for all formats equally.
In another embodiment, Δ_{F_PUCCH}(F) is defined for the different formats of sPUCCH. New target received powers P_{O_PUCCH}are defined for different TTI lengths. The new sPUCCH formats will have different target received powers than the current PUCCH formats, mostly because of the different TTI lengths. This may be captured in new P_{O_PUCCH}for the new sPUCCH formats. If the sPUCCH formats are defined in such a way that the target received power differs much from the target received power used today this is an alternative. Note that this would most likely still result in the need to define the same amount of new Δ_{F_PUCCH}(F).
Additionally, h(n_CQI, n_HARQ, n_SR) and Δ_TF,c(i) needs to be defined for new formats and TTI lengths.
The reference format for sPUCCH is proposed to be PUCCH format 1a. Some other reference format may be selected, but that would only make things more complicated.
For power prioritization within each different sTTI length, the same prioritization as for one millisecond TTI should be re-used. Accordingly, the power prioritization within each different sTTI length may be the same as for one millisecond TTI.
Since sTTI is used to reduce latency, it is also possible to prioritize sTTI over one millisecond TTI since that will to the furthest extent make sure that latency critical sTTI transmissions are carried out as soon as possible. Accordingly, with respect to power, sTTI may be prioritized over one millisecond TTI.
Prioritizing sTTI transmissions over one millisecond TTI transmissions may potentially ruin the one millisecond TTI transmission if the sTTI transmission is scheduled in the same subframe as the one millisecond TTI transmission and the UE is power limited. Because of this, if the UE is power limited it may not use multiple carriers together with sTTI. Accordingly, power limited UEs may not use multiple carriers together with sTTI.
In LTE, there are two different types of power headroom reports defined. Type 1 assumes PUSCH only transmission and type 2 assumes PUSCH and PUCCH transmission. The power headroom is in both cases defined per subframe and carrier as:
Power Headroom=Maximum allowed power−Estimated desired power.
The Maximum allowed power is the configured maximum power. The Estimated desired power is the ideal power to use for the current modulation, coding scheme, channel, or the like, assuming no restrictions in transmit power. As per definition, the power headroom may become negative if the UE is power limited. The power headroom report is transmitted by the UE together with the message, the report is triggered in the uplink grant.
The current definition of power headroom applies also to sTTI using the estimated desired power. Accordingly, the power headroom for sTTI may be calculated using the same principle as for one millisecond TTI using the desired power for the sTTI transmission. Further, the power headroom report if transmitted in sTTI may be based on sTTI transmission of that specific sTTI length.
As the ON/OFF periods in uplink will be shorter due to the shorter uplink TTI lengths, the ON/OFF and OFF/ON transient periods will be noticeable. These transient periods are defined to each be below 20 μsec., 2% of the subframe length. In practice due to the 20 μsec. ON/OFF transient period, the SC-FDMA symbols preceding and following an uplink transmission may not be usable for data transmission, see FIG. 13. With two symbols TTI length (i.e., 1/7 of the original length), each 20 μs period is now about 14% of the TTI length. As implementations typically perform significantly better than the 20 μs requirement, the ON/OFF time masks should be tightened to improve the short TTI transmission. Accordingly, absolute ON/OFF time masks may be tightened for short TTI lengths.

ABBREVIATIONS

Abbreviation Explanation

BLER Block Error Rate
CP Cyclic Prefix
DCI Downlink Control Information
DTX Discontinuous Transmission
ePDCCH enhanced Physical Downlink Control Channel
HTTP Hypertext Transfer Protocol
LTE Long Term Evolution
MAC Medium Access Control
MCS Modulation and Coding Scheme
OFDM Orthogonal Frequency Division Multiple Access
PDCCH Physical Downlink Control Channel
PDSCH Physical Downlink Shared Channel
PRB Physical Resource Block
PUCCH Physical Uplink Control Channel
PUSCH Physical Uplink Shared Channel
RAT Radio Access Technology
RB Resource Block
RE Resource Element
RRC Radio Resource Control
SC-FDMA Single Carrier-Frequency Division Multiple Access
sPDCCH short Physical Downlink Control Channel
sPDSCH short Physical Downlink Shared Channel
sPUCCH short Physical Uplink Control Channel
sPUSCH short Physical Uplink Shared Channel
SF SubFrame
TCP Transmission Control Protocol
TTI Transmission Time Interval
sTTI short Transmission Time Interval
UCI Uplink Control Information
UL Uplink

The previous detailed description is merely illustrative in nature and is not intended to limit the present disclosure, or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding field of use, background, summary, or detailed description. The present disclosure provides various examples, embodiments and the like, which may be described herein in terms of functional or logical block elements. The various aspects described herein are presented as methods, devices (or apparatus), systems, or articles of manufacture that may include a number of components, elements, members, modules, nodes, peripherals, or the like. Further, these methods, devices, systems, or articles of manufacture may include or not include additional components, elements, members, modules, nodes, peripherals, or the like.
Furthermore, the various aspects described herein may be implemented using standard programming or engineering techniques to produce software, firmware, hardware (e.g., circuits), or any combination thereof to control a computing device to implement the disclosed subject matter. It will be appreciated that some embodiments may be comprised of one or more generic or specialized processors such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the methods, devices and systems described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic circuits. Of course, a combination of the two approaches may be used. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.
The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computing device, carrier, or media. For example, a computer-readable medium may include: a magnetic storage device such as a hard disk, a floppy disk or a magnetic strip; an optical disk such as a compact disk (CD) or digital versatile disk (DVD); a smart card; and a flash memory device such as a card, stick or key drive. Additionally, it should be appreciated that a carrier wave may be employed to carry computer-readable electronic data including those used in transmitting and receiving electronic data such as electronic mail (e-mail) or in accessing a computer network such as the Internet or a local area network (LAN). Of course, a person of ordinary skill in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the subject matter of this disclosure.
Throughout the specification and the embodiments, the following terms take at least the meanings explicitly associated herein, unless the context clearly dictates otherwise. Relational terms such as “first” and “second,” and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The term “or” is intended to mean an inclusive “or” unless specified otherwise or clear from the context to be directed to an exclusive form. Further, the terms “a,” “an,” and “the” are intended to mean one or more unless specified otherwise or clear from the context to be directed to a singular form. The term “include” and its various forms are intended to mean including but not limited to. References to “one embodiment,” “an embodiment,” “example embodiment,” “various embodiments,” and other like terms indicate that the embodiments of the disclosed technology so described may include a particular function, feature, structure, or characteristic, but not every embodiment necessarily includes the particular function, feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may. The terms “substantially,” “essentially,” “approximately,” “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

Claims

1. A method in a wireless device of performing power control of a physical channel in a wireless communication system, comprising:

determining a transmission power for a transmission on the physical channel according to a power control loop, wherein the loop specifies the transmission power based on at least one parameter, with a value of the at least one parameter being dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel.

2. The method of claim 1, wherein the at least one parameter has a different value for each TTI length usable on the physical channel.

3. The method of any of claim 1, wherein the value of the at least one parameter further depends on which of different transmission formats defined as usable on the physical channel is selected for the transmission on the physical channel.

4. The method of claim 3 wherein the at least one parameter has a different value for each transmission format usable on the physical channel.

5. The method of claim 1, wherein the value of the at least one parameter is based on a power adjustment for the transmission on the physical channel having the selected TTI length.

6. The method of claim 1, wherein the value of the at least one parameter is based on a ratio of a power adjustment for the transmission on the physical channel having the selected TTI length and a power adjustment for the transmission on the physical channel having a predetermined TTI length.

7. The method of claim 1, wherein the value of the at least one parameter is based on a number of symbols in the transmission on the physical channel having the selected TTI length.

8. The method of claim 1, wherein the value of the at least one parameter is based on a ratio of a number of symbols in a transmission on the physical channel having the selected TTI length and a number of symbols in a transmission on the physical channel having a predetermined TTI length.

9. The method of claim 8, wherein the ratio is represented as follows:

1 0 \log_{1 0} (\frac{{TTIsymbols}_{selected}}{{TTIsymbols}_{predetermined}}),

wherein TTIsymbols_selectedis the selected number of TTI symbols, and TTIsymbols_{predetermined}is the predetermined number of TTI symbols.

10. The method of claim 8, wherein the ratio is further represented as follows:

a 10 \log_{1 0} (\frac{{TTIpilotsymbols}_{selected}}{{TTIpilotsymbols}_{predetermined}}) + b 10 \log_{1 0} (\frac{{TTIcontrolsymbols}_{selected}}{{TTIcontrolsymbols}_{predetermined}})

wherein the selected number of TTI symbols corresponds to a selected number of pilot symbols (TTIpilotsymbols_selected) and a selected number of control symbols (TTIcontrolsymbols_selected), and the predetermined number of TTI symbols corresponds to a predetermined number of pilot symbols (TTIpilotsymbols_{predetermined}) and a predetermined number of control symbols (TTIcontrolsymbols_{predetermined}) wherein a and bare constants.

11. The method of claim 1, wherein the value of the at least one parameter is based on a ratio of the selected TTI length and a predetermined TTI length.

12. The method of claim 8, wherein the ratio is represented as follows:

10 \log_{1 0} (\frac{{TTIlength}_{selected}}{{TTIlength}_{predetermined}}),

wherein TTIlength_selectedis the selected TTI length, and TTIlength_{predetermined}is the predetermined TTI length.

13. The method of claim 8, wherein the ratio is further represented as follows:

a 10 \log_{1 0} (\frac{{TTIpilotlength}_{selected}}{{TTIpilotlength}_{predetermined}}) + b 10 \log_{1 0} (\frac{{TTIcontrollength}_{selected}}{{TTIcontrollength}_{predetermined}}),

wherein the selected TTI length corresponds to a selected pilot symbols length (TTIpilotlength_selected) and a selected control symbols length (TTIcontrollength_seleted),

wherein the predetermined TTI length corresponds to a predetermined pilot symbols length (TTIpilotlength_{predetermined}) and a predetermined control symbols length (TTIcontrollength_{predetermined}), and

wherein a and bare constants.

14. The method of claim 1, wherein the selected TTI length or selected number of TTI symbols corresponds to a short TTI having a length of less than one millisecond or less than 14 symbols and/or the predetermined TTI length is one millisecond or the predetermined number of TTI symbols is fourteen.

15. The method of claim 1, wherein the value of the at least one parameter is based on a predetermined received power for the physical channel having the selected TTI length.

16. The method of claim 1, wherein the value of the at least one parameter is based on an adjustment that depends on whether frequency hopping is used for the transmission on the physical layer having the selected TTI length.

17. The method of claim 1, wherein the physical channel is a control channel and/or wherein the physical channel is an uplink channel.

18. A wireless device for performing power control of physical channels in a wireless communication system, the wireless device configured to:

determine a transmission power for a transmission on the physical channel according to a power control loop, wherein the loop specifies the transmission power based on at least one parameter, with a value of the at least one parameter being dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel.

19. A wireless device for performing power control of physical channels in a wireless communication system, comprising:

a processor and a memory, the memory containing instructions executable by the processor whereby the wireless device is configured to:

20. A wireless device (105, 200, 300, 400, 600) for performing power control of physical channels in a wireless communication system, the wireless device configured to:

receive from a network node (101, 800, 900, 1000), an indication of a value of at least one parameter (111) which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel, wherein a transmission power for a transmission on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.

21. The wireless device as claimed in claim 18, wherein the value of the at least one parameter further depends on which of different transmission formats defined as usable on the physical channel is selected for the transmission on the physical channel.

22. The wireless device as claimed in claim 18, wherein the value of the at least one parameter is based on a number of symbols in the transmission on the physical channel having the selected TTI length.

23. The wireless device as claimed in claim 18, configured to perform the method of any of claims 2-17.

24. A method in a wireless device (105, 200, 300, 400, 600) for performing power control of physical channels in a wireless communication system (100), comprising:

receiving, by the wireless device, from a network node (101, 800, 900, 1000),

an indication of a value of at least one parameter (111) which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel,

wherein a transmission power for a transmission on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.

25. The method of claim 24, further comprising:

determining the transmission power for the physical channel based on the parameter.

26. A method in a network node (101, 800, 900, 1000) for performing power control of physical channels in a wireless communication system (100), comprising:

transmitting (1103), by the network node, to a wireless device (105, 200, 300, 400, 600), an indication of a value of at least one parameter (111) which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel,

wherein a transmission power for a transmission by the wireless device on the physical channel is according to a power control loop, and wherein the power control loop specifies the transmission power based on the parameter.

27. A network node (101, 800, 900, 1000) for performing power control of physical channels in a wireless communication system (100), the network node configured to:

transmit (1103), to a wireless device (105, 200, 300, 400, 600), an indication of a value of at least one parameter (111) which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel,

28. A network node for performing power control of physical channels in a wireless communication system, comprising:

a processor and a memory, the memory containing instructions executable by the processor whereby the network node is configured to:

transmit (1103), to a wireless device (105, 200, 300, 400, 600), a value of at least one parameter (111) which is dependent on which of different transmission time interval (TTI) lengths defined as usable on the physical channel is selected for the transmission on the physical channel,

29. A computer program product stored in a non-transitory computer readable medium for controlling a wireless device in a communication system, the computer program product comprising software instructions which, when run on the wireless device, cause the wireless device to: