SRS signaling in 5G new radio wireless communications

A base station is configured to determine a sounding reference signal (SRS) configuration that has a plurality of cyclic shifts for a comb 8 SRS, a plurality of user equipment (UE) ports for transmitting the comb 8 SRS and a mapping of the plurality of cyclic shifts to the plurality of UE ports. The base station is further configured to transmit the SRS configuration to the UE.

BACKGROUND

When establishing the network connection such as, for example, a connection to a 5G new radio (NR) network, a user equipment (UE) transmits a sounding reference signal (SRS) to a next generation NodeB (gNB) to apprise the gNB of the uplink channel conditions. Based on the received SRS signal, the gNB can configure the UE with physical resources to use for communications between the UE and the gNB.

SUMMARY

Some exemplary embodiments are related to a processor of a base station configured to perform operations. The operations include determining a sounding reference signal (SRS) configuration having a plurality of cyclic shifts for a comb 8 SRS, a plurality of user equipment (UE) ports for transmitting the comb 8 SRS and a mapping of the plurality of cyclic shifts to the plurality of UE ports, and transmitting the SRS configuration to the UE.

Other exemplary embodiments are related to a base station having a transceiver configured to communicate with a user equipment (UE) and a processor communicatively coupled to the transceiver and configured to perform operations. The operations include determining a sounding reference signal (SRS) configuration having a plurality of cyclic shifts for a comb 8 SRS, a plurality of user equipment (UE) ports for transmitting the comb 8 SRS and a mapping of the plurality of cyclic shifts to the plurality of UE ports, and transmitting the SRS configuration to the UE.

Still further exemplary embodiments are related to a processor of a base station configured to perform operations. The operations include determining a resource block (RB)-level partial frequency sounding (RPFS) configuration having a configured subband size, an RPFS factor to be applied to the configured subband size, a reduced subband size based on the configured subband size and the RPFS factor and a resulting sounding reference signal (SRS) sequence length based on the configured subband size and the RPFS factor, and transmitting the RPFS configuration to the UE.

Additional Exemplary embodiments are related to a base station having a transceiver configured to communicate with a user equipment (UE) and a processor communicatively coupled to the transceiver and configured to perform operations. The operations include determining a resource block (RB)-level partial frequency sounding (RPFS) configuration having a configured subband size, an RPFS factor to be applied to the configured subband size, a reduced subband size based on the configured subband size and the RPFS factor and a resulting sounding reference signal (SRS) sequence length based on the configured subband size and the RPFS factor, and transmitting the RPFS configuration to the UE.

DETAILED DESCRIPTION

The exemplary embodiments may be further understood with reference to the following description and the related appended drawings, wherein like elements are provided with the same reference numerals. The exemplary embodiments relate to the configuration of a sounding reference signal (SRS) to support comb 8 and resource block (RB)-level partial frequency sounding (RPFS).

In addition, the exemplary embodiments are described with regard to a 5G New Radio (NR) network. However, reference to a 5G NR network is merely provided for illustrative purposes. The exemplary embodiments may be utilized with any network that implements the functionalities described herein.

To provide more flexibility to a 5G NR network in configuring SRS transmissions it was agreed in Release 16 of 3GPP that SRS transmissions could be transmitted in any symbol of a slot. However, SRS transmissions have been limited to comb 1, 2, or 4, thus limiting the number of UEs that can be multiplexed by a gNB.

According to some exemplary embodiments, a gNB configures a comb 8 SRS transmission and configures a cyclic shift, the number of ports, and a mapping of the cyclic shift to the number of ports for the comb 8 SRS transmission.

Another limitation with current SRS configurations is that the SRS transmissions can only be transmitted in contiguous physical resource blocks (PRBs), which limits the number of UEs that may be multiplexed in the same bandwidth.

According to further exemplary embodiments, the gNB configures the UE with an RPFS factor for the UE to determine a subset of PRBs on which to transmit the SRS, thus allowing for more UEs to be multiplexed on the same bandwidth.

FIG.1shows an exemplary network arrangement100according to various exemplary embodiments. The exemplary network arrangement100includes a UE110. It should be noted that any number of UE may be used in the network arrangement100. Those skilled in the art will understand that the UE110may be any type of electronic component that is configured to communicate via a network, e.g., mobile phones, tablet computers, desktop computers, smartphones, phablets, embedded devices, wearables, Internet of Things (IoT) devices, etc. It should also be understood that an actual network arrangement may include any number of UEs being used by any number of users. Thus, the example of a single UE110is merely provided for illustrative purposes.

The UE110may be configured to communicate with one or more networks. In the example of the network configuration100, the networks with which the UE110may wirelessly communicate are a 5G New Radio (NR) radio access network (5G NR-RAN)120, an LTE radio access network (LTE-RAN)122and a wireless local access network (WLAN)124. However, it should be understood that the UE110may also communicate with other types of networks and the UE110may also communicate with networks over a wired connection. Therefore, the UE110may include a 5G NR chipset to communicate with the 5G NR-RAN120, an LTE chipset to communicate with the LTE-RAN122and an ISM chipset to communicate with the WLAN124.

The 5G NR-RAN120and the LTE-RAN122may be portions of cellular networks that may be deployed by cellular providers (e.g., Verizon, AT&T, T-Mobile, etc.). These networks120,122may include, for example, cells or base stations (Node Bs, eNodeBs, HeNBs, eNBS, gNBs, gNodeBs, macrocells, microcells, small cells, femtocells, etc.) that are configured to send and receive traffic from UE that are equipped with the appropriate cellular chip set. The WLAN124may include any type of wireless local area network (WiFi, Hot Spot, IEEE 802.11x networks, etc.).

The UE110may connect to the 5G NR-RAN120via the gNB120A and/or the gNB120B. The gNBs120A and120B may be configured with the necessary hardware (e.g., antenna array), software and/or firmware to perform massive multiple in multiple out (MIMO) functionality. Massive MIMO may refer to a base station that is configured to generate a plurality of beams for a plurality of UE. During operation, the UE110may be within range of a plurality of gNBs. Reference to two gNBs120A,120B is merely for illustrative purposes. The exemplary embodiments may apply to any appropriate number of gNBs. Further, the UE110may communicate with the eNB122A of the LTE-RAN122to transmit and receive control information used for downlink and/or uplink synchronization with respect to the 5G NR-RAN120connection.

Those skilled in the art will understand that any association procedure may be performed for the UE110to connect to the 5G NR-RAN120. For example, as discussed above, the 5G NR-RAN120may be associated with a particular cellular provider where the UE110and/or the user thereof has a contract and credential information (e.g., stored on a SIM card). Upon detecting the presence of the 5G NR-RAN120, the UE110may transmit the corresponding credential information to associate with the 5G NR-RAN120. More specifically, the UE110may associate with a specific base station (e.g., the gNB120A of the 5G NR-RAN120).

In addition to the networks120,122and124the network arrangement100also includes a cellular core network130, the Internet140, an IP Multimedia Subsystem (IMS)150, and a network services backbone160. The cellular core network130may be considered to be the interconnected set of components that manages the operation and traffic of the cellular network. The cellular core network130also manages the traffic that flows between the cellular network and the Internet140. The IMS150may be generally described as an architecture for delivering multimedia services to the UE110using the IP protocol. The IMS150may communicate with the cellular core network130and the Internet140to provide the multimedia services to the UE110. The network services backbone160is in communication either directly or indirectly with the Internet140and the cellular core network130. The network services backbone160may be generally described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that may be used to extend the functionalities of the UE110in communication with the various networks.

FIG.2shows an exemplary UE110according to various exemplary embodiments. The UE110will be described with regard to the network arrangement100ofFIG.1. The UE110may represent any electronic device and may include a processor205, a memory arrangement210, a display device215, an input/output (I/O) device220, a transceiver225and other components230. The other components230may include, for example, an audio input device, an audio output device, a battery that provides a limited power supply, a data acquisition device, ports to electrically connect the UE110to other electronic devices, one or more antenna panels, etc. For example, the UE110may be coupled to an industrial device via one or more ports.

The processor205may be configured to execute a plurality of engines of the UE110. For example, the engines may include an SRS management engine235. The SRS engine235may perform various operations related to receiving an SRS configuration transmission from the gNB120A (or120B) and transmitting the SRS to the gNB.

The memory arrangement210may be a hardware component configured to store data related to operations performed by the UE110. The display device215may be a hardware component configured to show data to a user while the I/O device220may be a hardware component that enables the user to enter inputs. The display device215and the I/O device220may be separate components or integrated together such as a touchscreen. The transceiver225may be a hardware component configured to establish a connection with the 5G NR-RAN120, the LTE-RAN122, the WLAN124, etc. Accordingly, the transceiver225may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies).

FIG.3shows an exemplary network base station, in this case gNB120A, according to various exemplary embodiments. The gNB120A may represent any access node of the 5G NR network through which the UE110may establish a connection. The gNB120A illustrated inFIG.3may also represent the gNB120B.

The gNB120A may include a processor305, a memory arrangement310, an input/output (I/O) device320, a transceiver325, and other components330. The other components330may include, for example, a power supply, a data acquisition device, ports to electrically connect the gNB120A to other electronic devices, etc.

The processor305may be configured to execute a plurality of engines of the gNB120A. For example, the engines may include an SRS management engine335for performing operations including configuring a comb 8 SRS for and/or a RE-level partial frequency sounding (RPFS) for SRS transmissions of the UE110. Examples of this process will be described in greater detail below.

The above noted engine being an application (e.g., a program) executed by the processor305is only exemplary. The functionality associated with the engines may also be represented as a separate incorporated component of the gNB120A or may be a modular component coupled to the gNB120A, e.g., an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information. In addition, in some gNBs, the functionality described for the processor305is split among a plurality of processors (e.g., a baseband processor, an applications processor, etc.). The exemplary aspects may be implemented in any of these or other configurations of a gNB.

The memory310may be a hardware component configured to store data related to operations performed by the UEs110,112. The I/O device320may be a hardware component or ports that enable a user to interact with the gNB120A. The transceiver325may be a hardware component configured to exchange data with the UE110and any other UE in the system100. The transceiver325may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies). Therefore, the transceiver325may include one or more components (e.g., radios) to enable the data exchange with the various networks and UEs.

FIG.4shows a method400of configuring a comb 8 sounding reference signal (SRS) for the UE110according to various exemplary embodiments. At405, the gNB120A (or120B) configures the number of cyclic shifts (a phase ramping) for the comb 8 SRS transmissions. In some embodiments, the gNB120A configures the UE110with a maximum of six cyclic shifts (0, 1, 2, 3, 4, and 5) regardless of the SRS sequence length. In some embodiments, the gNB120A may configure the maximum number of cyclic shifts based on the SRS sequence length to advantageously allow for the configuration of a greater number of ports for the SRS transmission. For example, in some embodiments, if the SRS sequence length is an integer multiple of 6 but not an integer multiple of 8 or 12, then the gNB120A may configure the UE110with a maximum of six cyclic shifts. If the SRS sequence length is an integer multiple of 8 but not an integer multiple of 12, then the gNB120A may configure the UE110with a maximum of eight cyclic shifts (0, 1, 2, 3, 4, 5, 6, 7). If the SRS sequence length is an integer multiple of 12, then the gNB120A may configure the UE110with a maximum of twelve cyclic shifts (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11). In some embodiments, the minimum SRS subband size is configured to be 8 PRBs instead of the minimum 4 PRBs dictated by current 3GPP standards. In such an embodiment, the gNB120A may configure the UE110with a maximum of twelve cyclic shifts (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11).

At410, the gNB120A configures the number of ports for the comb 8 SRS transmission. In some embodiments, the gNB120A configures the UE110with a maximum of two ports (1 or 2 ports) for SRS comb 8 transmissions having six cyclic shifts (since 6 is divisible by 1 or 2). In some embodiments, the gNB120A configures the UE110with a maximum of four ports (1, 2, or 4 ports) for SRS comb 8 transmissions having eight or twelve cyclic shifts (since 8 and 12 are both divisible by 1, 2, or 4). In some embodiments, the gNB120A may configure the UE with a maximum of six ports (in addition to 1 or 2 ports) for SRS transmissions when the maximum number of configured cyclic shifts is six. In some embodiments, when the minimum SRS subband size is configured to be 8 PRBs instead of the minimum 4 PRBs dictated by current 3GPP standards, the gNB120A may configure the UE110with a maximum of four ports (1, 2, or 4) for the SRS transmissions.

At415, the gNB120A maps the configured cyclic shifts to the configured UE110ports. In some embodiments, the gNB120A maps the cyclic shifts to the configured ports to ensure that the cyclic shifts are equally spaced apart when mapped to the ports. For example, when six cyclic shifts (0, 1, 2, 3, 4, are configured and two ports are configured, the gNB120A may map the first port to 0 and the second port to 3 to ensure an equal distance between the mapped cyclic shifts. It should be noted that there are other mapping combinations that would also achieve this result (e.g., 1 and 4, 2 and 5, etc.). This equally spaced apart mapping is also applicable to embodiments in which a maximum of 8 and 12 cyclic shifts are configured with a maximum of 4 ports.

When comb 8 SRS transmissions are configured with a maximum of 6 cyclic shifts, the phase ramping values are defined by

i3⁢π,
where i is the corresponding cyclic shift (0, 1, 2, 3, 4, 5). In some embodiments, the gNB120A may alternatively explicitly configure the cyclic shift phase ramp for each SRS port. As a result, the gNB120A may multiplex more users using the same comb offset compared with the equally spaced apart mapping described above. In such an embodiment, the gNB120A may support a 6-port configuration when explicitly indicating the cyclic shift phase ramp as described.

In some embodiments, when comb 8 SRS transmissions are configured with a maximum of 6 cyclic shifts, in order to support a 4-port configuration, cyclicshift-n8 may be mapped to corresponding ports based on

ai=2⁢π⁢nSRScs,inSRScs,max,where⁢⁢nSRScsi=(nSRScs+(pi-1⁢0⁢0⁢0))⁢mod⁢nSRScs,max
where α1is the phase ramp for SRS port i, nSRScs,maxis the maximum number of cyclic shifts, nSRScsis configured cyclic shift (0, 1, 2, 3, 4, 5 for maximum 6 cyclic shifts), and piis the port index for SRS port i. As a result, it is not necessary that the number of cyclic shifts be a integer multiple of the number of ports, thus allowing the gNB120A to freely indicate the mapping of cyclic shifts to each port. At420, the gNB120A transmits the SRS configuration of405-415to the UE110. The gNB120A may include this SRS configuration in an RRC configuration message.

FIG.5shows a method500of configuring resource block (RB)-level partial frequency sounding (RPFS) for SRS transmissions according to various exemplary embodiments. At505, the gNB120A configures the SRS subband size (mSRS,BSRS), which may be based on Table 6.4.1.4.3-1 of 3GPP TS 38.211. At510, the gNB120A configures an RPFS factor (Pf) such that the subband size divided by the RPFS factor

(mSRS,BSRSPf)
yields the RPFS for the SRS transmission. In some embodiments, the determination of Pfmay be based on one or more constraints. In some embodiments, the one or more constraints may be that the resulting RPFS value must be an integer number. In some embodiments, the one or more constraints may additionally or alternatively be that the resulting RPFS value must be an integer multiple of 4. In some embodiments, the one or more constraints may additionally or alternatively be that the resulting RPFS value must be one of the subband sizes (mSRS,BSRS) listed in Table 6.4.1.4.3-1 of 3GPP TS 38.211. For example, if the configured subband size (mSRS,BSRS) is 224 and Pfis 2, the RPFS would be 112, which is one of the subband sizes listed in Table 6.4.1.4.3-1 of 3GPP TS 38.211. In some embodiments, the one or more constraints may additionally or alternatively be that the resulting RPFS value must result in an SRS sequence length supported by 3GPP Release 16 (e.g., sequence length of 6, 12, 18, 24, ≥36). The sequence length can be determined based on

1⁢2Pf*KTC⁢mSRS,BSRS
where KTCis the comb size and 12 is the number of resource elements (REs) in a PRB. In the above example, an RPFS of 112, when the Pfis 2 and the comb size (KTC) is 4, yields a sequence length of 168, which is greater than 36 and satisfies this constraint.

In some embodiments, an RPFS

(mSRS,BSRSPf)
having a non-integer value may be permitted. In such an embodiment, the RPFS may be rounded (floor, ceiling, or nearest) to one of the subband sizes (mSRS,BSRS) listed in Table 6.4.1.4.3-1 of 3GPP TS 38.211. For example, if the RPFS value is 86.5, the floor rounding of this value would yield subband size of 80, a ceiling rounding would yield a subband size of 88, and a nearest rounding would yield a subband size of 88. In some embodiments, the non-integer RPFS value may alternatively be rounded (floor, ceiling, or nearest) to the nearest integer that is a multiple of 4. In the above example of the RPFS value of 86.5, the floor rounding of this value would yield subband size of 84, a ceiling rounding would yield a subband size of 88, and a nearest rounding would yield a subband size of 88. In some embodiments, the non-integer RPFS value may alternatively be rounded (floor, ceiling, or nearest) to the nearest value that would yield an SRS sequence length supported by 3GPP Release 16 (e.g., sequence length of 6, 12, 18, 24, ≥36). In the above example of the RPFS value of 86.5 and a comb size (KTC) of 4, a floor rounding would yield a subband size of 86, a ceiling rounding would yield a subband size of 87, and a nearest rounding would yield a subband size of 87.

At515, the gNB120A determines the SRS sequence length based on the RPFS value. If the RPFS

(mSRS,BSRSPf)
value results in an SRS sequence length not supported by 3GPP Release 16 (e.g., sequence length of 6, 12, 18, 24, ≥36), then, in some embodiments, the RPFS value (PF) is not permitted. In some embodiments, the resulting RPFS may alternatively be rounded (floor, ceiling, or nearest) to the nearest SRS sequence length supported by 3GPP Release 16 (e.g., sequence length of 6, 12, 18, 24, ≥36). For example, if the RPFS value results in an SRS sequence length of 14.7, then the floor rounding of that sequence length is 12, the ceiling rounding is 18, and the nearest rounding is 12. In some embodiments, the currently supported SRS sequence length is alternatively truncated. In such an embodiment, the sequence length resulting from the RPFS is rounded (floor, ceiling, or nearest) to an integer sequence length. Subsequently, a base sequence is selected from the currently supported SRS sequence lengths (6, 12, 18, 24, ≥36). In some embodiments, the base sequence that is as long as or longer than the sequence length resulting from the RPFS is selected. In some embodiments, the base sequence that is as long as or longer than the sequence length resulting from the RPFS is selected, except that the base sequence length must be greater than or equal to 36. Finally, the selected base sequence length is truncated. At520, the gNB120A transmits the RPFS configuration to the UE110.