UPLINK POWER CONTROL ON UNLICENSED CARRIERS
20220272637 · 2022-08-25
Inventors
Cpc classification
H04W72/23
ELECTRICITY
H04W16/14
ELECTRICITY
H04W52/42
ELECTRICITY
H04W74/0808
ELECTRICITY
International classification
H04W16/14
ELECTRICITY
H04W52/36
ELECTRICITY
H04W52/42
ELECTRICITY
Abstract
Systems and methods relating to transmit power control are disclosed. In some embodiments, a method of operation of a radio access node for providing transmit power control commands to a wireless device for uplink (UL) transmission on a cell that operates in an unlicensed frequency spectrum is provided. The method comprises indicating, for the cell that operates in the unlicensed frequency spectrum, a dynamic Transmit Power Control (TPC) command using a downlink (DL) control channel which indicates a DL-UL allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum. In some embodiments, the DL control channel is a common DL control channel. In some other embodiments, the DL channel is a common Physical Downlink Control Channel (PDCCH).
Claims
1. A method of operating of a radio access node to provide transmit power control commands to a wireless device for use in uplink transmission, comprising: transmitting on a downlink control channel an indication to the wireless device for a cell that operates in unlicensed frequency spectrum, the indication comprising a dynamic transmit power control command which indicates a downlink-uplink allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum.
2. The method of claim 1, wherein the downlink control channel is a common downlink control channel.
3. The method of claim 1, wherein the downlink channel is a common physical downlink control channel.
4. The method of claim 1, wherein indicating the dynamic transmit power control command comprises transmitting the downlink control channel comprising an indication of the downlink-uplink allocation of upcoming subframes in the cell and an indication of the dynamic transmit power control command, wherein the indication of the dynamic transmit power control command comprises at least one bit.
5. The method of claim 1, wherein the dynamic transmit power control command is applicable to physical uplink shared channel, short physical uplink control channel, enhanced physical uplink control channel, and/or sounding reference signal transmissions.
6. The method of claim 1, wherein the radio access node is a Licensed Assisted Access (LAA) radio access node.
7. The method of claim 1, wherein the radio access node is a MuLTEfire (MF) access point.
8. A radio access node comprising: a processor; a transceiver in communication with the processor; and memory comprising instructions executable by the processor whereby the radio access node is operable to: transmitting an indication to a wireless device, configured for uplink transmission on a cell that operates in unlicensed frequency spectrum, a dynamic transmit power control command using a downlink control channel which indicates a downlink-uplink allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum.
9. The radio access node of claim 8, wherein the downlink control channel is a common downlink control channel.
10. The radio access node of claim 8, wherein the downlink channel is a common physical downlink control channel.
11. The radio access node of claim 8, wherein indicating the dynamic transmit power control command comprises transmitting the downlink control channel comprising an indication of the downlink-uplink allocation of upcoming subframes in the cell and an indication of the dynamic transmit power control command, wherein the indication of the dynamic transmit power control command comprises at least one bit.
12. The radio access node of claim 8, wherein the dynamic transmit power control command is applicable to physical uplink shared channel, short physical uplink control channel, enhanced physical uplink control channel, and/or sounding reference signal transmissions.
13. The radio access node of claim 8, wherein the radio access node is a Licensed Assisted Access, LAA, radio access node.
14. The radio access node of claim 8, wherein the radio access node is a MuLTEfire (MF) access point.
15. A method performed by a wireless device for uplink transmission, comprising: receiving, from a radio access node serving a cell that operates in unlicensed frequency spectrum, an indication of a dynamic transmit power control command for the cell that operates in the unlicensed frequency spectrum, the indication of the dynamic transmit power control command being comprised in a downlink control channel that also comprises an indication of a downlink-uplink allocation of upcoming subframes in the cell that operates in the unlicensed frequency spectrum.
16. The method of claim 15, further comprising utilizing the indication of the dynamic transmit power control command for uplink transmission on the cell that operates in the unlicensed frequency spectrum.
17. The method of claim 16, wherein utilizing the indication of the dynamic transmit power control command comprises: performing a Listen-Before-Talk (LBT) procedure for the cell that operates in the unlicensed frequency spectrum; and transmitting an uplink transmission on the cell that operates in the unlicensed frequency spectrum if a result of the LBT procedure is a decision that a corresponding channel is clear.
18. The method of claim 15, wherein the downlink control channel is a common downlink control channel.
19. The method of claim 15, wherein the downlink control channel is a common physical downlink control channel.
20. The method of claim 15, wherein the dynamic transmit power control command is applicable to physical uplink shared channel, short physical uplink control channel, enhanced physical uplink control channel, and/or sounding reference signal transmissions.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.
[0067]
[0068]
[0069]
[0070]
[0071]
[0072]
[0073]
[0074]
[0075]
[0076]
[0077]
[0078]
[0079]
[0080]
[0081]
[0082]
[0083]
[0084]
DETAILED DESCRIPTION
[0085] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.
[0086] Certain embodiments are provided in recognition of shortcomings of conventional approaches. One such shortcoming is that the combination of transmit Power Spectral Density (PSD) constraints in unlicensed bands and new features such as Multi-Subframe (MSF) scheduling introduce new challenges that are not well addressed with existing power control solutions. For example, coexistence with adjacent nodes of the same or another technology can be degraded when every User Equipment device (UE) that is scheduled in an uplink (UL) subframe utilizes the maximum allowed transmit power for that carrier.
[0087] In certain embodiments, an enhanced or evolved Node B (eNB) provides dynamic signaling of the UL/downlink (DL) allocation of upcoming subframes. This would be applicable to systems such as, e.g., MuLTEfire, Release (Rel) 14 enhanced License Assisted Access (eLAA), Long Term Evolution (LTE) in Rel-14 and beyond with MSF grant support, other versions of LTE in unlicensed bands, and Next Generation (NX)/Fifth Generation (5G) systems in unlicensed spectrum.
[0088] The described embodiments may provide various potential benefits compared to conventional approaches, such as improving the efficiency of UL power control on unlicensed carriers, and improving coexistence of UL transmissions with adjacent nodes of the same or another technology.
[0089] Certain embodiments relate to UL power control for UL transmissions on unlicensed bands. These transmissions may be carried on a Primary Cell (PCell) or Secondary Cell (SCell) in the case of Carrier Aggregation (CA) operation, or on Master eNB (MeNB) or Secondary eNB (SeNB) in case of dual connectivity, and may be sent in one or more successive UL subframes.
[0090]
[0091] As discussed above, embodiments of the present disclosure are applicable to, e.g., MuLTEfire, Rel-14 eLAA, LTE in Rel-14 and beyond with MSF grant support, other versions of LTE in unlicensed bands, and NX/5G systems in unlicensed spectrum. In this regard,
[0092]
[0093] Various embodiments of the operation of a wireless device 12 and a radio access node 24 (e.g., the radio access node 14, the LAA LPN 20, or the MF AP 22) will now be described with respect to
[0094] In a first embodiment, a MSF UL scheduling scenario is considered where a single grant from the eNB schedules Physical Uplink Shared Channel (PUSCH) and/or enhanced Physical Uplink Control Channel (ePUCCH) transmissions by a particular UE in L UL subframes, and where the L UL subframes may be non-consecutive. In one variation of this embodiment, the eNB may indicate multiple dynamic UL Transmit Power Control (TPC) commands corresponding to different UL subframes scheduled using the same grant, for example, L TPC commands in the same grant. This can be useful for example when different numbers of UEs are multiplexed in the L UL subframes and the eNB desires to limit the total UE transmit power radiated from all UEs in each subframe. In another variation of this embodiment, if the UE is configured to use accumulative TPC commands and a particular UL transmission in one of the scheduled subframes fails due to unsuccessful Listen-Before-Talk (LBT), then the UE continues to accumulate the indicated TPC command for that UL subframe prior to its next UL transmission attempt in a later UL subframe. In yet another variation of this embodiment, the switch between accumulative and absolute TPC is indicated dynamically in the MSF grant. In still another aspect of this embodiment, if the MSF grant also includes a joint grant for multiple unlicensed carriers, then additional TPC commands may be included corresponding to each unlicensed carrier.
[0095]
[0096] The MSF UL grant includes dynamic TPC commands for the L subframes (i.e., a dynamic TPC command for each of the L subframes). In this manner, the TPC commands can be dynamically sent for each subframe in each MSF UL grant. Further, in some embodiments, the MSF UL grant may be a joint grant for multiple carriers (e.g., multiple SCells operating in the unlicensed frequency spectrum), and the MSF UL grant includes dynamic TPC commands for each of those carriers. For example, if the L subframes include M subframes on carrier 1 and N subframes on carrier 2, then the MSF UL grant includes M TPC commands for the M subframes on carrier 1 and N TPC commands for the N subframes on carrier 2. Optionally, the MSF UL grant also includes an indication as to whether the dynamic TPC commands are accumulative or absolute TPC commands (i.e., an indication to the wireless device 12 as to whether to use accumulative or absolute TPC).
[0097] Based on the MSF UL grant, the wireless device 12 performs an LBT procedure to determine whether the wireless device 12 is permitted to transmit in SF(1), where SF(1) denotes the first subframe of the L subframes scheduled in the MSF UL grant (step 102). If the LBT procedure results in a decision that the corresponding channel in the unlicensed spectrum is clear, the wireless device 12 transmits a UL transmission in SF(1) in accordance with the TPC command for SF(1) included in the MSF UL grant (step 104). Notably, for eLAA, the UL transmission may be to a radio access node (e.g., the LAA LPN 20) other than the radio access node 24 that transmitted the MSF UL grant. In some embodiments, if accumulative TPC is used and the LBT procedure results in a decision that the corresponding channel in the unlicensed frequency spectrum is not clear, the wireless device 12 continues to accumulate the indicated TPC command for SF(1) prior to its next UL transmission attempt in SF(2) (i.e., the second subframe scheduled by the MSF UL grant). The wireless device 12 continues in this manner to perform LBT and transmit if the channel is clear for SF(2) through SF(L), which are the second through last subframes scheduled in the MSF UL grant (steps 106-112).
[0098] In a second embodiment, cell-specific dynamic TPC commands are indicated by the eNB using the Common Physical Downlink Control Channel (C-PDCCH) which indicates the DL-UL allocation of upcoming subframes. As a non-limiting example, 2 bits or 1 bit may be used for such indications, similar to Downlink Control Information (DCI) Formats 3 and 3A, respectively. These TPC commands may either be accumulative or absolute, and may be applicable to PUSCH, short PUCCH (sPUCCH), ePUCCH, or Sounding Reference Signal (SRS) transmissions.
[0099]
[0100] In some embodiments, the radio access node 24 transmits a UL grant to the wireless device 12 for transmission in the unlicensed spectrum (step 202). The wireless device 12 performs an LBT procedure to determine whether the corresponding channel is available for transmission, e.g., in the granted UL subframe (step 204). If the channel is clear, the wireless device 12 transmits a UL transmission in a UL subframe in accordance with the corresponding TPC command that was previously received by the wireless device 12 in the C-PDCCH (step 206). In the example of
[0101] A third embodiment addresses the case where the UE is configured with autonomous UL transmission capability, i.e., the UE can perform UL transmissions without an explicit UL grant from the serving cell. In one aspect of this embodiment, the UE sets its UL power control parameters based on the most recent C-PDCCH or UL grant power control information received by it. In another aspect, the UE that performs autonomous UL transmissions on serving cell c sets its power control parameters based on signaling received on another serving cell c′.
[0102]
[0103] In a fourth embodiment, a UE configured with a MSF grant may send a Power Headroom Report (PHR) in some or all of such said subframes, depending on eNB configuration. In one variation of this embodiment, the UE may send only the PHR corresponding to the subframe with the highest PUSCH transmission power.
[0104]
[0105] In a fifth embodiment, the eNB partitions UEs into different transmit power groups and manages the UL UE scheduling based on these groups and the number of UEs that need to be multiplexed in different UL subframes. For example, the eNB may schedule multiple cell-edge UEs with a higher required UL transmit power in the same subframe, while cell-center UEs with a lower required UL transmit power are multiplexed in another subframe.
[0106]
[0107] Although wireless devices 12 may represent communication devices that include any suitable combination of hardware and/or software, these wireless devices 12 may, in certain embodiments, represent devices such as the example wireless devices 12 illustrated in greater detail by
[0108] Referring to
[0109]
[0110] Referring to
[0111]
[0112] As indicated by the foregoing, certain embodiments are provided for UL power control on unlicensed carriers, with example application to Rel-14 eLAA and MuLTEfire.
[0113] While the disclosed subject matter has been presented above with reference to various embodiments, it will be understood that various changes in form and details may be made to the described embodiments without departing from the overall scope of the disclosed subject matter.
[0114] The following acronyms are used throughout this disclosure. [0115] μs Microsecond [0116] 3GPP Third Generation Partnership Project [0117] 5G Fifth Generation [0118] ACK Acknowledgement [0119] AP Access Point [0120] ASIC Application Specific Integrated Circuit [0121] B-IFDMA Block Interleaved Frequency Division Multiple Access [0122] CA Carrier Aggregation [0123] CC Component Carrier [0124] CCA Clear Channel Assessment [0125] CFI Control Format Indicator [0126] C-PDCCH Common Physical Downlink Control Channel [0127] CPU Central Processing Unit [0128] CRC Cyclic Redundancy Check [0129] C-RNTI Cell Radio Network Temporary Identifier [0130] CRS Cell Specific Reference Symbol [0131] CSMA/CA Carrier Sense Multiple Access with Collision Avoidance [0132] dBm Decibel-Milliwatt [0133] DCI Downlink Control Information [0134] DFT Discrete Fourier Transform [0135] DIFS Distributed Inter-Frame Space [0136] DL Downlink [0137] DMRS Demodulation Reference Signal [0138] DSP Digital Signal Processor [0139] DwPTS Downlink Pilot Time Slot [0140] eLAA Enhanced License Assisted Access [0141] eNB Enhanced or Evolved Node B [0142] ePDCCH Enhanced Physical Downlink Control Channel [0143] ePUCCH Enhanced Physical Uplink Control Channel [0144] FDMA Frequency Division Multiple Access [0145] FPGA Field Programmable Gate Array [0146] LAA License Assisted Access [0147] LBT Listen-Before-Talk [0148] LPN Low-Power Node [0149] LTE Long Term Evolution [0150] GHz Gigahertz [0151] M2M Machine-to-Machine [0152] MCOT Maximum Channel Occupancy Time [0153] MCS Modulation and Coding Scheme [0154] MeNB Master Enhanced or Evolved Node B [0155] MF MuLTEfire [0156] MHz Megahertz [0157] ms Millisecond [0158] MSF Multi-Subframe [0159] MTC Machine Type Communication [0160] NX Next Generation [0161] OFDM Orthogonal Frequency Division Multiplexing [0162] PCell Primary Cell [0163] PDCCH Physical Downlink Control Channel [0164] PHR Power Headroom Report [0165] PRACH Physical Random Access Channel [0166] PSD Power Spectral Density [0167] PUCCH Physical Uplink Control Channel [0168] PUSCH Physical Uplink Shared Channel [0169] RB Resource Block [0170] Rel Release [0171] SCell Secondary Cell [0172] SC-FDMA Single Carrier Frequency Division Multiple Access [0173] SeNB Secondary Enhanced or Evolved Node B [0174] sPUCCH Short Physical Uplink Control Channel [0175] SRS Sounding Reference Signal [0176] TPC Transmit Power Control [0177] TS Technical Specification [0178] TXOP Transmit Opportunity [0179] UE User Equipment [0180] UL Uplink [0181] WLAN Wireless Local Area Network
[0182] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.