Scheduling multiple subframes in unlicensed spectrum
11470641 · 2022-10-11
Assignee
Inventors
- Havish Koorapaty (Saratoga, CA)
- Jung-Fu Cheng (Fremont, CA)
- Sorour Falahati (Stockholm, SE)
- Amitav Mukherjee (Fremont, CA, US)
Cpc classification
H04W72/23
ELECTRICITY
International classification
Abstract
According to some embodiments, a method for use in a user equipment (UE) of transmitting uplink data in unlicensed spectrum comprises receiving, from a network node, an uplink grant comprising an indication of one or more subframes to use for transmitting uplink data. Each subframe comprises a plurality of symbols. The method further comprises obtaining an indication of a listen-before-talk (LBT) type. The LBT type indicates a type of LBT procedure that the UE should perform before transmitting uplink data. The method further comprises determining, using the obtained LBT type, at least one of a starting symbol and a stopping symbol for transmitting uplink data, and transmitting uplink data according to at least one of the determined starting symbol and the determined stopping symbol.
Claims
1. A method for use in a user equipment (UE) of transmitting uplink data in unlicensed spectrum, the method comprising: receiving, from a network node, downlink control information, DCI, comprising an indication of one or more subframes to use for transmitting the uplink data, each subframe comprising a plurality of symbols; obtaining an indication of a listen-before-talk (LBT) type, the LBT type indicating a type of LBT procedure that the UE should perform before transmitting the uplink data; determining, using the obtained LBT type, a starting symbol for transmitting the uplink data; and transmitting the uplink data according to at least one of the determined starting symbol; wherein: the LBT type indicates an LBT procedure with full random backoff or a short clear channel assessment (CCA) procedure; and the method further comprising: determining the UE is scheduled to transmit a sounding reference signal (SRS) in a last symbol of the plurality of symbols of a last subframe indicated by the DCI; and not transmitting the scheduled SRS.
2. The method of claim 1, wherein: the LBT type indicates the LBT procedure with full random backoff; and the starting symbol comprises a second symbol of the plurality of symbols of a first subframe indicated by the DCI.
3. The method of claim 1, wherein: the LBT type indicates the short CCA procedure; and the starting symbol comprises a symbol 25 μs after a first symbol of the plurality of symbols of a first subframe indicated by the DCI.
4. The method of claim 1, wherein obtaining the indication of the LBT type comprises receiving signaling from the network node.
5. The method of claim 1, wherein obtaining the indication of the LBT type comprises obtaining a predetermined LBT type unless the LBT type is signaled from the network node.
6. A user equipment (UE) operable to transmit uplink data in unlicensed spectrum, the UE comprising a memory coupled to processing circuitry, the processing circuitry operable to: receive, from a network node, downlink control information, DCI, comprising an indication of one or more subframes to use for transmitting the uplink data, each subframe comprising a plurality of symbols; obtain an indication of a listen-before-talk (LBT) type, the LBT type indicating a type of LBT procedure that the UE should perform before transmitting the uplink data; determine, using the obtained LBT type, at least one of a starting symbol and a stopping symbol for transmitting the uplink data; and transmit the uplink data according to at least one of the determined starting symbol and the determined stopping symbol; wherein: the LBT type indicates an LBT procedure with full random backoff or a short clear channel assessment (CCA) procedure; and the stopping symbol comprises a next to last symbol of the plurality of symbols of a last subframe indicated by the DCI; the UE being further configured to: determine the UE is scheduled to transmit a sounding reference signal (SRS) in a last symbol of the plurality of symbols of the last subframe indicated by the DCI; and not transmit the scheduled SRS.
7. The UE of claim 6, wherein: the LBT type indicates the LBT procedure with full random backoff; and the starting symbol comprises a second symbol of the plurality of symbols of a first subframe indicated by the DCI.
8. The UE of claim 6, wherein: the LBT type indicates the short CCA procedure; and the starting symbol comprises a symbol 25 μs after a first symbol of the plurality of symbols of a first subframe indicated by the DCI.
9. The UE of claim 6, wherein the processing circuitry is operable to obtain the indication of the LBT type by receiving signaling from the network node.
10. The UE of claim 6, wherein the processing circuitry is operable to obtain the indication of the LBT type by obtaining a predetermined LBT type unless the LBT type is signaled from the network node.
11. The UE of claim 9, wherein the processing circuitry is operable to receive the signaling from the network node by receiving common signaling over a broadcast channel.
12. The UE of claim 9, wherein the processing circuitry is operable to receive the signaling from the network node by receiving direct signaling over a unicast channel.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) For a more complete understanding of the embodiments and their features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
DETAILED DESCRIPTION
(18) Long term evolution (LTE) equipment may operate in the unlicensed 5 GHz radio spectrum according to the Third Generation Partnership Project (3GPP) initiative referred to as License Assisted Access (LAA). The unlicensed 5 GHz spectrum is used as a complement to the licensed spectrum. Accordingly, devices connect in the licensed spectrum (primary cell or PCell) and use carrier aggregation to benefit from additional transmission capacity in the unlicensed spectrum (secondary cell or SCell).
(19) Regulatory requirements may not permit transmissions in the unlicensed spectrum without prior channel sensing. This is because the unlicensed spectrum is shared with radios of similar or dissimilar wireless technologies. Wireless devices may perform channel sensing using a listen-before-talk (LBT) method. The LBT method includes sensing the transmission medium for a pre-defined minimum amount of time and backing off if the channel is busy. The maximum duration of a single transmission burst may be limited to a fixed time.
(20) The form of LBT may depend on the number of UEs that are scheduled, the number of subframes that are scheduled in succession, the length of the previous transmissions on the carrier, and/or other such factors. Some parameters related to LBT may be signaled by the eNB to UEs so that the UEs may perform LBT before transmission. The signaling parameters, however, do not fully encompass all the use cases and problems that may be encountered for uplink transmissions in unlicensed spectrum.
(21) When an eNB obtains an opportunity to transmit in unlicensed spectrum, the transmit opportunity may be shared with UEs that the eNB is serving. Transitions between transmissions from the eNB to transmissions from UEs may be handled in two ways, one where the UEs perform an LBT operation prior to transmission and one where the UEs do not perform an LBT operation.
(22) Performing LBT may generally include two broad categories of LBT operation. A first type uses an LBT procedure with full random backoff similar to what is used by IEEE 802.11 compliant nodes. These schemes are also referred to as Category 4 LBT schemes. A random backoff counter is picked randomly in the contention window. The size of the contention window may be approximately doubled every time a collision on the channel is detected. Thus, this procedure may also be referred to as a binary exponential backoff.
(23) In the second type of LBT procedure, a UE may perform an LBT operation for a fixed duration (e.g., 25 μs). Generally, the second type of LBT is preferable for transitions between downlink and uplink transmissions, because it minimizes the probability of another node completing its LBT operations and commencing transmissions on the channel. Many situations, however, may need to use a Category 4 LBT scheme.
(24) 3GPP specifications may include multi-subframe scheduling for Rel-14 LAA where one or more uplink grants transmitted in a single subframe can schedule uplink data in multiple subframes. The parameters that are signaled as part of the multi-subframe scheduling grant include hybrid ARQ acknowledgements (HARQ-ACKs) and related parameters. Specifically, the grants include legacy parameters (i.e., the new data indication (NDI), redundancy version (RV), and the HARQ-ACK bits themselves, which generally consist of one bit per transport block that is being acknowledged).
(25) Signaling of LBT parameters for LAA may use both explicit and implicit methods. The solutions include signaling of random backoff parameters such as the random backoff counter, contention window sizes, and the LBT priority class to be used. The signaling of these parameters may vary depending on factors such as the load and the set of UEs being multiplexed in a single subframe. Implicit signaling of the LBT priority class to be used can be based on various factors including the number of contiguous subframes that have been scheduled to the UE.
(26) Existing signaling and contention window management methods, however, do not fully account for the problems that arise when using implicit signaling to indicate contention window size that the UE must use. When explicit signaling is used, it creates unnecessarily large signaling overhead.
(27) Particular embodiments obviate the problems described above and include signaling LBT parameters for a Category 4 LBT scheme to a UE more efficiently, while ensuring that requirements on management of contention windows are met. Particular embodiments facilitate the management of uplink transmissions in unlicensed spectrum by providing the ability to vary the gaps between transmissions by different nodes. Some embodiments include signaling to enable the functionality.
(28) The embodiments described herein are applicable to both LAA LTE and standalone LTE-U operation, and in general for any system such as LTE operating in unlicensed spectrum or any spectrum where listen-before-talk protocols are used and where there is some fixed timing where transmissions occur.
(29) The following description sets forth numerous specific details. It is understood, however, that embodiments may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.
(30) References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.
(31) Particular embodiments are described with reference to
(32)
(33) In general, wireless devices 110 that are within coverage of network node 120 (e.g., within cell 115 served by network node 120) communicate with network node 120 by transmitting and receiving wireless signals 130. For example, wireless devices 110 and network node 120 may communicate wireless signals 130 containing voice traffic, data traffic, and/or control signals. A network node 120 communicating voice traffic, data traffic, and/or control signals to wireless device 110 may be referred to as a serving network node 120 for the wireless device 110. Communication between wireless device 110 and network node 120 may be referred to as cellular communication. Wireless signals 130 may include both downlink transmissions (from network node 120 to wireless devices 110) and uplink transmissions (from wireless devices 110 to network node 120).
(34) Each network node 120 may have a single transmitter or multiple transmitters for transmitting signals 130 to wireless devices 110. In some embodiments, network node 120 may comprise a multi-input multi-output (MIMO) system. Similarly, each wireless device 110 may have a single receiver or multiple receivers for receiving signals 130 from network nodes 120 or other wireless devices 110.
(35) Wireless signals 130 may include frames and subframes, such as those described with respect to
(36) Network node 120 may operate in a licensed frequency spectrum, such as an LTE spectrum. Network node 120 may also operate in an unlicensed frequency spectrum, such as a 5 GHz Wi-Fi spectrum. In an unlicensed frequency spectrum, network node 120 may coexist with other devices such as IEEE 802.11 access points and terminals. To share the unlicensed spectrum, network node 120 may perform LBT protocols before transmitting or receiving wireless signals 130. Wireless device 110 may also operate in one or both of licensed or unlicensed spectrum and in some embodiments may also perform LBT protocols before transmitting wireless signals 130. Both network node 120 and wireless device 110 may also operate in licensed shared spectrum.
(37) For example, network node 120a may operate in a licensed spectrum and network node 120b may operate in an unlicensed spectrum. Wireless device 110 may operate in both licensed and unlicensed spectrum. In particular embodiments, network nodes 120a and 120b may be configurable to operate in a licensed spectrum, an unlicensed spectrum, a licensed shared spectrum, or any combination. Although the coverage area of cell 115b is illustrated as included in the coverage area of cell 115a, in particular embodiments the coverage areas of cells 115a and 115b may overlap partially, or may not overlap at all.
(38) In particular embodiments, wireless device 110 and network nodes 120 may perform carrier aggregation. For example, network node 120a may serve wireless device 110 as a PCell and network node 120b may serve wireless device 110 as a SCell. Network nodes 120 may perform self-scheduling or cross-scheduling. If network node 120a is operating in licensed spectrum and network node 120b is operating in unlicensed spectrum, network node 120a may provide license assisted access to the unlicensed spectrum (i.e., network node 120a is a LAA PCell and network node 120b is a LAA SCell).
(39) In particular embodiments, network node 120a may dynamically schedule uplink and downlink subframes for wireless device 110. For example, in particular embodiments network node 120a may determine a first uplink/downlink scheduling pattern for a first plurality of consecutive subframes. Network node 120a may transmit the first uplink/downlink scheduling pattern to wireless device 110 (e.g., using (E)PDCCH) and transmit at least one subframe to wireless device 110 according to the first uplink/downlink scheduling pattern.
(40) If network node 120a received additional downlink data, or a request for uplink transmission from a wireless device, for example, then network node 120a may determine a second uplink/downlink scheduling pattern for a second plurality of consecutive subframes. Network node 120a may transmit the second uplink/downlink scheduling pattern to wireless device 110 in any of the subframes previously scheduled for wireless device 110.
(41) In particular embodiments, the uplink/downlink scheduling pattern may comprise a number of subsequent downlink subframes, a number of subsequent downlink and uplink subframes, an indication of which subframes to monitor or not monitor for downlink, or any other suitable pattern.
(42) In particular embodiments, wireless device 110 may receive, from network node 120 (e.g., using (E)PDCCH), a first uplink/downlink scheduling pattern for a first plurality of consecutive subframes. Wireless device 110 may receive at least one subframe according to the first uplink/downlink scheduling pattern. In one of the scheduled downlink subframes, wireless device 110 may receive a second uplink/downlink scheduling pattern for a second plurality of consecutive subframes.
(43) According to some embodiments, wireless device 110 may receive, from network node 120, an uplink grant comprising an indication of one or more subframes to use for transmitting uplink data. Each subframe comprises a plurality of symbols. Wireless device 110 may obtain an indication of a LBT type. The LBT type indicates a type of LBT procedure that the UE should perform before transmitting uplink data. Wireless device 110 may determine, using the obtained LBT type, at least one of a starting symbol and a stopping symbol for transmitting uplink data. Wireless device 110 may transmit uplink data according to at least one of the determined starting symbol and the determined stopping symbol.
(44) According to some embodiments, wireless device 110 may receive, from network node 120, an indication of a last subframe x that is within a maximum channel occupancy time (MCOT) limit based on a downlink burst after a successful category 4 LBT procedure performed by the network node. Wireless device 110 may transmit uplink data in the one or more subframes of the uplink grant prior to subframe x based on a short clear channel assessment (CCA) procedure, and transmit uplink data in the one or more subframes of the uplink grant after subframe x based on a category 4 LBT procedure.
(45) Although particular embodiments are described with respect to licensed or unlicensed spectrum, license assisted access, and/or carrier aggregation, the embodiments described herein apply equally to uplink and downlink scheduling in any spectrum and with respect to a single cell or any combination of cells.
(46) In wireless network 100, each network node 120 may use any suitable radio access technology, such as long term evolution (LTE), LTE-Advanced, UMTS, HSPA, GSM, cdma2000, NR, WiMax, WiFi, and/or other suitable radio access technology. Wireless network 100 may include any suitable combination of one or more radio access technologies. For purposes of example, various embodiments may be described within the context of certain radio access technologies. However, the scope of the disclosure is not limited to the examples and other embodiments could use different radio access technologies.
(47) As described above, embodiments of a wireless network may include one or more wireless devices and one or more different types of radio network nodes capable of communicating with the wireless devices. The network may also include any additional elements suitable to support communication between wireless devices or between a wireless device and another communication device (such as a landline telephone). A wireless device may include any suitable combination of hardware and/or software. For example, in particular embodiments, a wireless device, such as wireless device 110, may include the components described with respect to
(48) The following embodiments describe LBT parameters for a Category 4 LBT scheme that may be signaled to the UE more efficiently while ensuring that requirements on management of contention windows are met. Particular embodiments manage the contention window size of a Category 4 LBT scheme used by the UE in a particular uplink subframe. Particular embodiments may enable the management of uplink transmissions in unlicensed spectrum by providing the ability to vary the gaps between transmissions by different nodes. Gaps may be varied by varying the start or stop symbols for transmission in an uplink subframe.
(49) Particular embodiments include implicit signaling of a start symbol based on LBT type. For example, in some embodiments the explicit signaling of the start symbol of the PUSCH in the first subframe of a set of subframes that is allocated in a single uplink grant message may be avoided. The start symbol of the PUSCH may instead be obtained from the LBT type which may be signaled to the UE. The options for the LBT type may include a category 4 LBT scheme, a short 25 μs CCA, or no LBT.
(50) Some embodiments may use the following procedure to determine the start symbol of the PUSCH in the first allocated subframe. If the LBT type is Category 4, then PUSCH starts at symbol 1. If the LBT type is a CCA of 25 μs, then PUSCH starts 25 μs after the start of symbol 0. If the LBT type is no LBT and it is known that other technologies are present in the band, PUSCH starts 16 μs after the start of symbol 0. If the LBT type is no LBT and it is known that other technologies are not present in the band (e.g., via configuration by an entity that controls frequency channel allocation), then the PUSCH starts at the symbol boundary of symbol 0. Other embodiments may determine a start symbol using any suitable offset.
(51) Particular embodiments include signaling that indicates how LBT parameters are signaled. For example, particular embodiments may signal certain LBT parameters via dedicated signaling; whereas, some other embodiments may signal certain LBT parameters via common signaling to all UEs.
(52) As a particular example, if a network node is to signal an LBT type for a certain set of subframes for which the starting subframe may vary by up to 8 subframes and the number of subframes in the set may vary by up to 4 subframes, then five bits are required to indicate the LBT type and the number of subframes for which the LBT type is applicable. However, because uplink grants already include information on location of the allocations in time, the LBT type for the first of these subframes can be indicated by one additional bit in the dedicated uplink grant.
(53) If the number of UEs scheduled for the subframes is less than five, then the dedicated signaling is not wasteful. However, if the number of UEs to be scheduled in the subframes far exceeds five, then a common message in the C-PDCCH may be more efficient in indicating the subframe where a certain LBT type is to be used. Common messages in the C-PDCCH can also be used to indicate LBT parameters to be used for autonomous uplink transmissions which occur without explicit scheduling grants.
(54) In some embodiments, whether LBT parameters are signaled via common signaling (e.g., the C-PDCCH on an LAA SCell) or signaled via dedicated signaling (e.g., the DCI message conveying uplink grants to the UEs) may be configured via radio resource control (RRC) signaling at a higher layer. This provides the eNB flexibility to optimize the efficiency of the dynamic signaling based on the deployment and number of UEs to be served on average in a subframe in the cell. If dedicated signaling does not need to be used, then the bits that would have been used for signaling may be used for some other purpose.
(55) Particular embodiments include signaling a maximum channel occupancy time (MCOT) limit to the UE. For example, in some embodiments when there is a downlink transmission from an eNB in subframe n in a downlink transmission burst after a successful Category 4 LBT with an associated MCOT, the eNB can determine the subframe (e.g., subframe n+x) that meets the MCOT limit. That means the uplink transmission by UEs before that subframe (i.e., subframe n+x−1) can be based on a CCA of 25 μs, while the uplink transmission from that subframe (i.e., subframe n+x) may be based on Category 4 LBT until the UE detects a new downlink transmission.
(56) In embodiments with common signaling to all UEs, the eNB may signal the value of x using k bits. The number k can be fixed or can be configured by higher layers. For example larger number of k can be used at low loads and smaller number of k can be used at high loads.
(57) In embodiments with dedicated signaling, in a first approach the eNB can signal x using k bits, as mentioned above. In a second approach, the eNB signals how many of the scheduled subframes among the N subframes indicated in the dedicated signaling are subject to Category 4 LBT (or CCA based on 25 us LBT) transmission. In a third approach, the eNB ensures that in every scheduling grant for a set of subframes only one type of LBT option is valid. Thus, by using one bit the eNB can signal if the scheduled subframes corresponding to the grant in the dedicated signaling (i.e., uplink grant) are subject to CCA of 25 us or Category 4 LBT.
(58) Particular embodiments include signaling of an end symbol based on LBT type. For example, particular embodiments include four LBT priority classes that a UE can use to perform Category 4 LBT. Depending on the type of traffic to be sent on the uplink, the UE can choose the LBT priority class accordingly, similar to Wi-Fi or Rel-13 LAA. For example, LBT priority class 1, 2, 3 and 4 may correspond to VoIP, Video, Best effort and Background traffic, respectively.
(59) Based on a buffer status, the eNB is aware of the possible QoS of the potential uplink traffic. The eNB may use this knowledge, together with the number of scheduled uplink subframes, to understand the LBT priority class that the UE will use in case it performs Category 4 LBT. Moreover, from knowledge of whether the previous retransmissions have failed or not, the eNB knows whether the UE will increase the contention window size.
(60) Depending on the size of the contention window, the eNB can determine whether UEs performing Category 4 LBT can benefit from a larger gap than one symbol at the end of the subframe that is not going to be interfered by other UEs. If a larger gap is needed, the eNB may signal to the UE(s) to provide that gap. Another reason for providing larger gaps includes the scenario where a downlink transmission based on Category 4 LBT follows after the uplink transmission.
(61) In embodiments with common signaling, the eNB may signal all the UEs that can have uplink transmission based on CCA of 25 us LBT, not to transmit in the last symbol at the MCOT limit. This can be done using one bit. In the event that one or more such UEs were also requested to send aperiodic SRS in the same subframe, the SRS transmission in symbol thirteen may be dropped and the gap instruction may be prioritized. The eNB may also use an additional bit to indicate to all UEs subject to uplink transmission based on Category 4 to finish their last uplink transmission one symbol before the subframe boundary. The signaling to UEs using both types of LBT types may be signaled using the same bit as well.
(62) In the case where the eNB schedules transmissions such that in every scheduling grant for a set of subframes only one type of LBT option is valid, the eNB can use one bit to signal to the UE to finish its last uplink transmission one symbol before the subframe boundary.
(63) Particular embodiments include implicit or explicit signaling of the NO-LBT option. For example, particular embodiments include conditions that UE would be allowed to transmit in uplink without performing LBT.
(64) An example for the no-LBT condition is described in the 3GPP specifications. In the 3GPP example, no LBT is required for any uplink transmission that begins no later than 16 μs after the end of a downlink transmission. The eNB should ensure that the uplink transmission is within the MCOT limit. The duration of the uplink transmission should include at least UCI or SRS, and its duration shall not exceed 1 ms.
(65) Thus, when a UE fulfills the above conditions, it may transmit within 16 us without LBT while fulfilling the requirements on the uplink transmission without any signaling from the eNB (for example its duration and also its content). However, if two or more UEs are scheduled simultaneously after downlink subframes, but not all of them meet the conditions for no-LBT transmission (such as no UCI or SRS to be transmitted in the first uplink subframe immediately after downlink subframe), then the eNB may determine that the UEs that are eligible for no-LBT transmission need to perform LBT. That can be done using one bit. The bit can be sent by common signaling or dedicated signaling and can be a part of the signaling options as outlined in the embodiments described above.
(66) Other embodiments may use one bit in the common signaling or dedicated signaling to inform UE(s) eligible to transmission without LBT, to perform uplink transmission without LBT whenever the condition is met. In some embodiments, the eNB may assume whenever UE is eligible for transmission without LBT, the UE transmits without LBT and no signaling may be needed. In particular embodiments, signaling for the no LBT option is avoided by restricting it for use only in the ending partial subframe.
(67) Particular embodiments include signaling LBT information to the UE with a combination of dedicated and common signaling. For example, in particular embodiments the signaling of LBT parameters may be performed by a combination of dedicated and common signaling. According to one example, the UE may be provided allocations for uplink transmissions via dedicated signaling with the LBT type signaling not being signaled to the UE. The UE may assume that it should use a 25 μs CCA for the first subframe in the allocation unless otherwise indicated by common signaling. The common signaling that can be used to provide such indication can, for example, be the MCOT limits as described in other embodiments. In a variation of this embodiment, the UE may assume that it should use a Category 4 LBT procedure for the first subframe in the allocation unless otherwise indicated by common signaling.
(68) Other example combinations of common and dedicated signaling that may be included in some embodiments include: (a) signaling of LBT type via dedicated signaling and ending symbol of PUSCH via common signaling; (b) signaling of ending symbol of PUSCH via dedicated signaling and LBT type via common signaling (in one variation, the LBT type may be implicitly signaled using signaling on the MCOT limit); and (c) signaling of all LBT parameters via common signaling but signaling the downlink subframe number where the common signaling is to be received in the dedicated signaling
(69) The examples and embodiments described above may be represented generally by the flow diagrams in
(70)
(71) The method begins at step 1012, where a wireless device receives an uplink grant comprising an indication of one or more subframes to use for transmitting uplink data. Each subframe comprises a plurality of symbols. For example, wireless device 110 may receive an uplink grant from network node 120. The uplink grant may include a burst of 3 subframes where each subframe comprises 14 OFDM symbols.
(72) At step 1114, the wireless device obtains an indication of a LBT type. The LBT type indicates a type of LBT procedure that the UE should perform before transmitting uplink data. For example wireless device 110 may obtain an LBT type from network node 120. The LBT type may refer to a category 4 LBT procedure, a CCA, or no LBT procedure.
(73) In particular embodiments, the wireless device may obtain the LBT type via dedicated signaling. For example, the wireless device may receive the LBT type as part of its uplink grant (i.e., unicast). Or the wireless device may receive the LBT type via common signaling, such as broadcast on the C-PDCCH.
(74) In particular embodiments, obtaining the LBT type may comprise obtaining a predetermined default LBT type. For example, wireless device 110 may be preconfigured to use a category 4 LBT procedure unless otherwise signaled by network node 120. In particular embodiments, the wireless device may obtain the LBT type according to any of the examples or embodiments described above.
(75) At step 1116, the wireless device determines, using the obtained LBT type, at least one of a starting symbol and a stopping symbol for transmitting uplink data. For example, wireless device 110 may use the LBT type to determine whether any gap should be added to the beginning or end of the uplink transmission.
(76) As particular examples, if the LBT type indicates a category 4 procedure, then the starting symbol may comprise the second symbol of the plurality of symbols of the first subframe indicated by the uplink grant (i.e., OFDM symbol 1 for a subframe with 14 symbols numbered 0-13). If the LBT type indicates a short CCA procedure, then the starting symbol comprises the symbol 25 μs after the first symbol of the plurality of symbols of the first subframe indicated by the uplink grant (i.e., 25 μs after OFDM symbol 0 for a subframe with 14 symbols numbered 0-13). If the LBT type indicates no LBT procedure, and the UE determines that other radio technologies are present in the unlicensed spectrum, then the starting symbol comprises the symbol 16 μs after the first symbol of the plurality of symbols of the first subframe indicated by the uplink grant (i.e., 16 μs after OFDM symbol 0 for a subframe with 14 symbols numbered 0-13). If the LBT type indicates no LBT procedure, and the UE determines that other radio technologies are not present in the unlicensed spectrum, then the starting symbol comprises the first symbol of the plurality of symbols of the first subframe indicated by the uplink grant (i.e., OFDM symbol 0 for a subframe with 14 symbols numbered 0-13).
(77) As further examples, if the LBT type indicates a category 4 procedure or a short clear channel assessment (CCA) procedure, then the stopping symbol comprises the next to last symbol of the plurality of symbols of the last subframe indicated by the uplink grant (i.e., OFDM symbol 12 for a subframe with 14 symbols numbered 0-13). In some embodiments, if the wireless device is supposed to transmit SRS in the last symbol of the subframe, then the wireless device may determine not to transmit the SRS.
(78) Particular embodiments may determine a starting or stopping symbol according to any of the examples or embodiments described above. Although particular examples are given, other embodiments may use any suitable starting symbol or any suitable stopping symbol.
(79) At step 1118, the wireless device transmits uplink data according to at least one of the determined starting symbol and the determined stopping symbol. For example, wireless device 110 may transmit a PUSCH using at least one of the starting or stopping symbols determined in the previous step.
(80) Modifications, additions, or omissions may be made to method 1100. Additionally, one or more steps in method 1100 of
(81)
(82) The method begins at step 1212, where a wireless device receives an uplink grant comprising an indication of one or more subframes to use for transmitting uplink data. For example, wireless device 110 may receive an uplink grant from network node 120.
(83) At step 1214, the wireless device receives an indication of a last subframe x that is within a MCOT limit based on a downlink burst after a successful category 4 LBT procedure performed by the network node. For example, network node 120 may have performed a successful category 4 LBT procedure and transmitted downlink information to one or more wireless devices 110. The downlink may not have consumed the full amount of time available within the MCOT limit, leaving time available for wireless device 110 to transmit some uplink data without performing its own category 4 LBT procedure.
(84) The wireless device may receive the indication via common or direct signaling according to any of the examples and embodiments described above. The subframe x may be indicated by a an offset (e.g., x subframes from the first subframe in the uplink grant) or by any of the examples or embodiments described above.
(85) At step 1216, the wireless device transmits uplink data in the one or more subframes of the uplink grant prior to subframe x based on a short CCA procedure. For example, wireless device 110 may perform a CCA procedure and then transmit uplink up to the MCOT limit.
(86) At step 1218, the wireless device transmits uplink data in the one or more subframes of the uplink grant after subframe x based on a category 4 LBT procedure. For example, wireless device 110 may perform a category 4 LBT procedure just after the MCOT limit and then continue to transmit uplink data to network node 120 assuming the LBT procedure was successful.
(87) Modifications, additions, or omissions may be made to method 1200. Additionally, one or more steps in method 1200 of
(88)
(89) For example, the wireless device may receive an uplink grant comprising an indication of one or more subframes to use for transmitting uplink data; obtain an indication of a LBT type; determine, using the obtained LBT type, at least one of a starting symbol and a stopping symbol for transmitting uplink data; and transmit uplink data according to at least one of the determined starting symbol and the determined stopping symbol.
(90) As another example, the wireless device may receive an uplink grant; receive an indication of a last subframe x that is within a MCOT limit; transmit uplink data in one or more subframes of the uplink grant prior to subframe x based on a short clear CCA procedure; and transmit uplink data in the one or more subframes of the uplink grant after subframe x based on a category 4 LBT procedure.
(91) Particular examples of a wireless device include a mobile phone, a smart phone, a PDA (Personal Digital Assistant), a portable computer (e.g., laptop, tablet), a sensor, a modem, a machine type (MTC) device/machine to machine (M2M) device, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, a device-to-device capable device, a vehicle-to-vehicle device, or any other device that can provide wireless communication. The wireless device includes transceiver 1310, processing circuitry 1320, memory 1330, and power source 1340. In some embodiments, transceiver 1310 facilitates transmitting wireless signals to and receiving wireless signals from wireless network node 120 (e.g., via an antenna), processing circuitry 1320 executes instructions to provide some or all of the functionality described herein as provided by the wireless device, and memory 1330 stores the instructions executed by processing circuitry 1320. Power source 1340 supplies electrical power to one or more of the components of wireless device 110, such as transceiver 1310, processing circuitry 1320, and/or memory 1330.
(92) Processing circuitry 1320 includes any suitable combination of hardware and software implemented in one or more integrated circuits or modules to execute instructions and manipulate data to perform some or all of the described functions of the wireless device. In some embodiments, processing circuitry 1320 may include, for example, one or more computers, one more programmable logic devices, one or more central processing units (CPUs), one or more microprocessors, one or more applications, and/or other logic, and/or any suitable combination of the preceding. Processing circuitry 1320 may include analog and/or digital circuitry configured to perform some or all of the described functions of wireless device 110. For example, processing circuitry 1320 may include resistors, capacitors, inductors, transistors, diodes, and/or any other suitable circuit components.
(93) Memory 1330 is generally operable to store computer executable code and data. Examples of memory 1330 include computer memory (e.g., Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (e.g., a hard disk), removable storage media (e.g., a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information.
(94) Power source 1340 is generally operable to supply electrical power to the components of wireless device 110. Power source 1340 may include any suitable type of battery, such as lithium-ion, lithium-air, lithium polymer, nickel cadmium, nickel metal hydride, or any other suitable type of battery for supplying power to a wireless device.
(95) In particular embodiments, processing circuitry 1320 in communication with transceiver 1310 performs LBT procedures before transmitting in the uplink. Processing circuitry 1320 in communication with transceiver 1310 adapts a transmission gap before or after an uplink transmission based on a signaled LBT type.
(96) For example, processing circuitry 1320 in communication with transceiver 1310 may receive an uplink grant comprising an indication of one or more subframes to use for transmitting uplink data; obtain an indication of a LBT type; determine, using the obtained LBT type, at least one of a starting symbol and a stopping symbol for transmitting uplink data; and transmit uplink data according to at least one of the determined starting symbol and the determined stopping symbol.
(97) As another example, processing circuitry 1320 in communication with transceiver 1310 may receive an uplink grant; receive an indication of a last subframe x that is within a MCOT limit; transmit uplink data in one or more subframes of the uplink grant prior to subframe x based on a short clear CCA procedure; and transmit uplink data in the one or more subframes of the uplink grant after subframe x based on a category 4 LBT procedure.
(98) Other embodiments of the wireless device may include additional components (beyond those shown in
(99)
(100) Receiving module 1350 may perform the receiving functions of wireless device 110. For example, receiving module 1350 may receive uplink scheduling from a network node. In some embodiments, receiving module 1350 may receive configuration information, such as an indication of an LBT type or an MCOT limit, from a network node. Receiving module 1350 may perform the receiving functions described in any of the examples and embodiments described above. In certain embodiments, receiving module 1350 may include or be included in processing circuitry 1320. In particular embodiments, receiving module 1350 may communicate with determining module 1352 and transmitting module 1356.
(101) Determining module 1352 may perform the determining functions of wireless device 110. For example, determining module 1352 may determine a starting or stopping symbol for uplink transmission as described in any of the examples and embodiments above. Determining module 1352 may determine what type of LBT procedure to perform based on the received MCOT limit. In certain embodiments, determining module 1352 may include or be included in processing circuitry 1320. In particular embodiments, determining module 1352 may communicate with receiving module 1350 and transmitting module 1356.
(102) Transmitting module 1356 may perform the transmitting functions of wireless device 110. For example, transmitting module 1356 may transmit uplink subframes to network node 120 according to any of the determined starting symbol, stopping symbol, and/or LBT type. In certain embodiments, transmitting module 1356 may include or be included in processing circuitry 1320. In particular embodiments, transmitting module 1356 may communicate with receiving module 1350 and determining module 1352.
(103)
(104) Network node 120 can be an eNodeB, a nodeB, a base station, a wireless access point (e.g., a Wi-Fi access point), a low power node, a base transceiver station (BTS), a transmission point or node, a remote RF unit (RRU), a remote radio head (RRH), or other radio access node. The network node includes at least one transceiver 1410, at least one processing circuitry 1420, at least one memory 1430, and at least one network interface 1440. Transceiver 1410 facilitates transmitting wireless signals to and receiving wireless signals from a wireless device, such as wireless devices 110 (e.g., via an antenna); processing circuitry 1420 executes instructions to provide some or all of the functionality described above as being provided by a network node 120; memory 1430 stores the instructions executed by processing circuitry 1420; and network interface 1440 communicates signals to backend network components, such as a gateway, switch, router, Internet, Public Switched Telephone Network (PSTN), controller, and/or other network nodes 120. Processing circuitry 1420 and memory 1430 can be of the same types as described with respect to processing circuitry 1320 and memory 1330 of
(105) In some embodiments, network interface 1440 is communicatively coupled to processing circuitry 1420 and refers to any suitable device operable to receive input for network node 120, send output from network node 120, perform suitable processing of the input or output or both, communicate to other devices, or any combination of the preceding. Network interface 1440 includes appropriate hardware (e.g., port, modem, network interface card, etc.) and software, including protocol conversion and data processing capabilities, to communicate through a network.
(106) In particular embodiments, processing circuitry 1420 in communication with transceiver 1410 signals LBT parameters to a wireless device. Other embodiments of network node 120 include additional components (beyond those shown in
(107)
(108) Determining module 1450 may perform the determining functions of network node 120. For example, determining module 1450 may determine a MCOT limit. In certain embodiments, determining module 1450 may include or be included in processing circuitry 1420. In particular embodiments, determining module 1450 may communicate with sending module 1452.
(109) Sending module 1452 may perform the sending functions of network node 120. For example, sending module 1452 may send a MCOT limit or LBT type to wireless device 110. In certain embodiments, sending module 1452 may include or be included in processing circuitry 1420. In particular embodiments, sending module 1452 may communicate with determining module 1450.
(110) Modifications, additions, or omissions may be made to the systems and apparatuses disclosed herein without departing from the scope of the invention. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set.
(111) Modifications, additions, or omissions may be made to the methods disclosed herein without departing from the scope of the invention. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order.
(112) Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure, as defined by the claims below.
(113) Abbreviations Used in the Preceding Description Include:
(114) 3GPP Third Generation Partnership Project
(115) ACK Acknowledgement
(116) BTS Base Transceiver Station
(117) CCA Clear Channel Assessment
(118) CW Contention Window
(119) D2D Device to Device
(120) DCF Distributed Coordination Function
(121) DIFS DCF Inter-Frame Spacing
(122) DL Downlink
(123) eNB eNodeB
(124) FDD Frequency Division Duplex
(125) HARQ Hybrid Automatic Repeat Request
(126) LAA License Assisted Access
(127) LBT Listen-Before-Talk
(128) LTE Long Term Evolution
(129) MAC Medium Access Control
(130) M2M Machine to Machine
(131) MIMO Multi-Input Multi-Output
(132) MRBC Multiple Random Backoff Channels
(133) MTC Machine Type Communication
(134) NAK Negative Acknowledgement
(135) NR New Radio
(136) PDSCH Physical Downlink Shared Channel
(137) PIFS PCF Inter-Frame Spacing
(138) PUCCH Physical Uplink Control Channel
(139) QCI QoS Class Indicator
(140) QoS Quality of Service
(141) RAN Radio Access Network
(142) RAT Radio Access Technology
(143) RB Radio Bearer
(144) RBS Radio Base Station
(145) RNC Radio Network Controller
(146) RRC Radio Resource Control
(147) RRH Remote Radio Head
(148) RRU Remote Radio Unit
(149) SCell Secondary Cell
(150) SRBC Single Random Backoff Channel
(151) SIFS Short Inter-Frame Spacing
(152) TDD Time Division Duplex
(153) UE User Equipment
(154) UL Uplink
(155) UTRAN Universal Terrestrial Radio Access Network
(156) WAN Wireless Access Network