HK1261862B - Srs design method and apparatus for unlicensed carriers - Google Patents

Description

SRS design method and device for unlicensed carriers

Technical Field

The present disclosure relates to wireless communication technology, and more particularly to a reference signal, such as a sounding reference signal, that can be used for an unlicensed carrier.

Background Art

The ongoing Standalone LTE-U Forum and the future 3GPP Rel-14 work item on Uplink Granted Assisted Access (LAA) aim to allow LTE UEs to transmit on the uplink in the unlicensed 5 GHz or licensed shared 3.5 GHz radio spectrum. For the case of Standalone LTE-U (respectively the MulteFire (MF) project), the initial random access and subsequent UL transmissions occur entirely on the unlicensed spectrum. Regulatory requirements may not allow transmissions in the unlicensed spectrum without prior channel sensing. Since the unlicensed spectrum has to be shared with other radios of similar or dissimilar wireless technologies, a so-called Listen Before Talk (LBT) approach needs to be applied to channel sensing. LBT consists of sensing the medium for a predefined minimum time and backing off if the channel is busy. Therefore, the initial Random Access (RA) procedure for Standalone LTE-U should consist of as few transmissions as possible and also have low latency so that the number of LBT operations can be minimized and the RA procedure can then be completed as quickly as possible.

Today, the unlicensed 5GHz spectrum is primarily used for devices that implement the IEEE 802.11 wireless local area network (WLAN) standard, also known under its marketing brand as "Wi-Fi."

Summary of the Invention

It is an object of the present disclosure to provide an improved approach for reference signaling in the context of carriers or frequency ranges accessed using an LBT based approach.

Therefore, a terminal for a wireless communication network is disclosed. The terminal is adapted to perform a listen-before-talk (LBT) process for one or more transmission bandwidths. In addition, the terminal is adapted to send PUSCH signaling in a physical uplink shared channel (PUSCH) subframe on one or more interlaces within the one or more transmission bandwidths. The terminal is further adapted to send sounding reference signaling (SRS) on the one or more interlaces in the PUSCH subframe. The terminal may include corresponding processing and/or control circuits, and/or radio circuits (e.g., transmitters). Alternatively or additionally, the terminal may include one or more corresponding modules, for example, an LBT module and/or a PUSCH module and/or an SRS module.

Specifically, a user equipment (UE) for a MuLTEFire wireless communication network may be considered. The user equipment includes processing circuitry and a transmitter. The user equipment is adapted to utilize the processing circuitry and the transmitter to perform the following operations: perform a listen-before-talk (LBT) procedure for one or more transmission bandwidths, and transmit physical uplink shared channel (PUSCH) signaling in PUSCH subframes on one or more interlaces within the one or more transmission bandwidths, and transmit sounding reference signaling on the one or more interlaces in the PUSCH subframes.

Furthermore, a method of operating a terminal in a wireless communication network, the terminal being adapted to perform a listen-before-talk (LBT) procedure for one or more transmission bandwidths, is described. The method comprises transmitting Physical Uplink Shared Channel (PUSCH) signaling in PUSCH subframes on one or more interlaces within the one or more transmission bandwidths, and transmitting sounding reference signaling on the one or more interlaces in the PUSCH subframes.

Specifically, a method for operating a user equipment in a MuLTEFire wireless communication network may be considered. The method includes: performing a listen-before-talk (LBT) procedure for one or more transmission bandwidths; sending physical uplink shared channel (PUSCH) signaling in PUSCH subframes on one or more interlaces within the one or more transmission bandwidths; and sending sounding reference signaling on the one or more interlaces in the PUSCH subframes.

It can be considered that the sending of PUSCH signaling and/or reference signaling (especially SRS) is based on the LBT process. Specifically, if the LBT process is successful, the corresponding transmission (related to the transmission bandwidth) can be performed. Generally, the sending of PUSCH signaling and/or reference signaling/SRS can be based on the configuration. It can be considered that the sending of PUSCH signaling and reference signaling/SRS is based on the same LBT process. The LBT process can usually be performed before the relevant transmission of, for example, PUSCH signaling and/or SRS. Generally, PUSCH signaling and reference signaling can be considered as uplink signaling. Different LBT processes can be performed for different transmission bandwidths, for example, so that each LBT process is independent of other processes (for example, in terms of possible results, and/or with respect to different transmission bandwidths). Different transmission bandwidths can be adjacent transmission bandwidths and/or non-overlapping transmission bandwidths.

Generally, sending the sounding reference signaling may include multiplexing the sounding reference signaling sent on different antenna ports via frequency division and/or based on cyclic shift.An antenna port may be considered to be associated with a transmitting terminal.

Sending sounding reference signaling may be considered to include sending sounding reference signaling at the end (in the time domain) of a PUSCH subframe (specifically, in the last symbol of the PUSCH subframe). The last symbol may be an SC-FDMA (Single Carrier Frequency Division Multiple Access) symbol, or in some cases (e.g., in the context of 5G technologies such as 3GPP New Radio (NR)) an OFDMA (Orthogonal Frequency Division Multiple Access) symbol. The sounding reference signaling may cover (only) the last symbol or the last two symbols. Alternatively or additionally, the sounding reference signaling may cover the same frequency and/or subcarriers as the PUSCH signaling and/or a portion thereof in the frequency domain, e.g., as defined according to one or more interlaces.

Also considered is a network node for a wireless communication network. The network node is adapted to estimate channel conditions based on sounding reference signaling received from at least one terminal. Receiving the sounding reference signaling includes receiving PUSCH signaling in a physical uplink shared channel (PUSCH) subframe on one or more interlaces, and receiving the sounding reference signaling on the one or more interlaces in the PUSCH subframe. The network node may include corresponding processing or control circuitry, and/or corresponding radio circuitry (e.g., a receiver). Alternatively or additionally, the network node may include one or more corresponding modules, such as an estimation module and/or a reception module and/or an SRS reception module and/or a PUSCH reception module.

An access point for a MuLTE Fire wireless communication network is described, the access point comprising processing circuitry and a receiver. The access point is adapted to estimate channel conditions using the processing circuitry and the receiver based on sounding reference signaling received from at least one user equipment for the MuLTE Fire wireless communication network, wherein receiving the sounding reference signaling comprises receiving physical uplink shared channel (PUSCH) signaling in PUSCH subframes on one or more interlaces, and receiving the sounding reference signaling on the one or more interlaces in the PUSCH subframes.

A method for operating a network node in a wireless communication network is discussed. The method includes estimating channel conditions based on sounding reference signaling received from at least one terminal, wherein receiving the sounding reference signaling includes receiving Physical Uplink Shared Channel (PUSCH) signaling in a PUSCH subframe on one or more interlaces, and receiving the sounding reference signaling on the one or more interlaces in the PUSCH subframe.

Furthermore, a method for operating an access point in a MuLTE Fire wireless communication network is provided. The method includes estimating channel conditions based on sounding reference signaling received from at least one user equipment for the MuLTE Fire wireless communication network. Receiving the sounding reference signaling includes receiving physical uplink shared channel (PUSCH) signaling in PUSCH subframes on one or more interlaces, and receiving the sounding reference signaling on the one or more interlaces in the PUSCH subframes.

Receiving PUSCH signaling and/or SRS may be based on a configuration that may be provided by a network node and/or configured to the transmitting terminal. Specifically, the receiver and/or network node (respectively, its circuitry) may be configured to receive and/or demodulate and/or decode and/or interpret the received signaling according to the described signaling transmission structure.

The sounding reference signaling may be considered to be sent at the end (in the time domain) of a PUSCH subframe (specifically, in the last symbol of the PUSCH subframe). The last symbol may be an SC-FDMA (Single Carrier Frequency Division Multiple Access) symbol, or in some cases (e.g., in the context of 5G technologies such as 3GPP New Radio (NR)) an OFDMA (Orthogonal Frequency Division Multiple Access) symbol. The sounding reference signaling may cover (only) the last symbol or the last two symbols. Alternatively or additionally, the sounding reference signaling may cover the same frequency and/or subcarriers as the PUSCH signaling and/or a portion thereof in the frequency domain, e.g., as defined according to one or more interlaces.

Typically, sounding reference signaling sent on different antenna ports and/or by different users can be multiplexed via frequency division and/or based on cyclic shifts. This multiplexing can be based on a configuration determined and/or configured, for example, by a network node. It can be assumed that the network node that configures the terminal knows the corresponding configuration. It should be noted that the transmission bandwidth of a receiver is the bandwidth at which it receives (but represents the bandwidth at which the transmitter transmits). In addition, receiver signaling from different transmitters can be multiplexed, for example, so that the receiver can determine which signaling comes from which transmitter. The configuration determined and/or provided by the network node or the receiver can, for example, indicate such multiplexing for each individual terminal and/or for a group comprising more than one terminal.

It is also contemplated that there is a program product comprising a code executable by a control circuit (or a processing circuit), the code causing the processing or control circuit to perform and/or control any of the methods described herein.

Also disclosed is a carrier medium that carries and/or stores the program product described herein.

The methods described herein allow reference signaling to be transmitted in the same context (e.g., on the same frequency resources (e.g., subcarriers) as PUSCH signaling) without the need to perform additional LBT procedures. This improves reliability and allows for improved use of resources subject to LBT access.

The terminal may be considered to be implemented as a user equipment, in particular a user equipment of MuLTEFire. The network node may be implemented as a base station of MuLTEFire, which may be referred to as an access point.

The transmission bandwidth may represent a frequency bandwidth and/or range. The transmission bandwidth may be, for example, the system bandwidth, and/or the bandwidth of a carrier and/or carrier aggregation, and/or the bandwidth over which an LBT process must be performed for access according to a rule. Interleaving may generally represent a bandwidth within a transmission bandwidth, and/or may be considered to be contained within a bandwidth, and/or may represent a portion of a bandwidth. Interleaving may include a frequency range (e.g., a continuous range and/or two or more discontinuous ranges) for a transmission (e.g., scheduled and/or expected and/or reserved) particularly for one terminal (e.g., a transmission on a PUSCH and/or for reference signaling such as an SRS). In some variants, interleaving may additionally include a frequency range (e.g., a continuous range and/or two or more discontinuous ranges) that is blocked and/or exempted from transmission (by the same UE or terminal) (e.g., scheduled and/or expected and/or reserved) by the same UE or terminal. This does not exclude that other terminals or devices may utilize a frequency range that is blocked and/or exempted from the above-mentioned transmission. Typically, interleaving may be block-based.

The sounding reference signaling may be reference signaling that is unrelated to the PUSCH signaling, eg, not intended and/or used for demodulation and/or decoding, and/or modulated and/or coded independently of the PUSCH signaling.

It may generally be considered that, as an alternative or in addition to sending PUSCH signaling, sPUCCH (shortened PUCCH) signaling is sent, for example, in one or more interlaces and/or in a similar manner as described with respect to PUSCH signaling. For sPUCCH, the sounding reference signaling may cover one, two, three or four symbols in the time domain and/or cover the subcarriers and/or a portion thereof used for transmission of sPUCCH in the frequency domain. In some cases, SRS signaling may replace and/or represent sPUCCH signaling. The sPUCCH SRS structure may depend on the presence of an LBT gap between sPUCCH and PUSCH, for example, on whether an LBT procedure has to be performed between the transmission of sPUCCH signaling and PUSCH signaling.

A PUSCH subframe may be considered as a subframe where PUSCH signaling is scheduled and/or configured and/or expected. The network node may be adapted to and/or may configure such a subframe, for example using UL grant signaling and/or using implicit scheduling.

Estimating the channel or channel conditions may include determining timing and/or path loss and/or interference associated with the channel and/or signaling used for the estimation.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are provided to illustrate the concepts and methods described herein and are not intended to limit their scope unless otherwise specifically stated.

The accompanying drawings include:

Figure 1 shows the LTE downlink physical resources;

Figure 2 shows the LTE time domain structure;

FIG3 shows a Rel-12 uplink subframe;

FIG4 illustrates an exemplary Licensed Assisted Access (LAA) to unlicensed spectrum;

FIG5 shows the allocation of a first interlace;

FIG6 shows an example of SRS design;

FIG7 shows an example of SRS design;

FIG8 shows an example of SRS design;

FIG9 shows an exemplary SRS in sPUCCH;

FIG10 schematically illustrates a terminal; and

FIG11 schematically illustrates a network node.

DETAILED DESCRIPTION

Long Term Evolution (LTE) is discussed below. It should be noted that in the context of this description, LTE can be considered as representative of wireless communication networks that use LBT to access carriers or spectrum and/or use reference signaling such as SRS, but the methods described herein are not necessarily limited to LTE and can be used for other technologies, such as narrowband and/or MulteFire.

LTE describes a telecommunications standard that uses OFDM in the downlink and DFT-spread OFDM (also known as single-carrier FDMA, SC-FDMA) in the uplink. The basic LTE downlink physical resources can therefore be viewed as a time-frequency grid as shown in the figure, where each resource element (RE) corresponds to one OFDM subcarrier during one OFDM symbol interval. An uplink subframe has the same subcarrier spacing as the downlink and the same number of SC-FDMA symbols in the time domain as the OFDM symbols in the downlink.

Figure 1 shows LTE downlink physical resources.

In the time domain, LTE downlink transmissions are organized into 10ms radio frames, each consisting of ten equally sized subframes of length Tsubframe = 1ms, as shown in Figure 1. Each subframe includes two time slots of 0.5ms duration, and the slot numbers within the frame range from 0 to 19. With a normal cyclic prefix, a subframe consists of 14 OFDM symbols. Each symbol has a duration of approximately 71.4μs (including the cyclic prefix).

FIG2 shows the LTE time domain structure.

Furthermore, resource allocation in LTE is usually described in terms of resource blocks (RBs), where an RB corresponds to 12 consecutive subcarriers in the frequency domain. Resource blocks are numbered starting from 0 at one end of the system bandwidth in the frequency domain.

In LTE, uplink transmissions are dynamically scheduled. That is, in a downlink subframe, the base station sends control information about which terminals should send data to the eNB in the subsequent subframe and on which resource blocks to send the data. The uplink resource grid includes data and uplink control information in the PUSCH, uplink control information in the PUCCH, and various reference signals such as the Demodulation Reference Signal (DMRS) and Sounding Reference Signal (SRS). An example uplink subframe is shown in Figure 3.

It is worth noting that UL DMRS and SRS are time-division multiplexed into the UL subframe, and SRS is always sent in the last symbol of a normal UL subframe. DMRS is used for coherent demodulation of PUSCH and PUCCH data. For subframes with a normal cyclic prefix, PUSCH DMRS is sent once per slot and is located in the fourth and eleventh SC-FDMA symbols. SRS is not directly associated with other data or control information, but for the purpose of frequency selective scheduling, SRS can usually be used (by a receiving network node, such as an eNodeB) to estimate the uplink channel quality. To achieve this, SRSs with different sounding bandwidths from different UEs must be able to overlap. As shown in Figure 3, interleaved FDMA is used for SRS with a repetition factor of 2, which means that in the configured SRS bandwidth, the SRS will be mapped to every other subcarrier in a comb-like manner.

FIG3 shows a Rel-12 uplink subframe.

Licensed Assisted Access (LAA) to unlicensed spectrum using (but not limited to) LTE in this example is discussed below.

Until now, the spectrum used by LTE has been dedicated to LTE. The advantage is that LTE systems do not need to worry about coexistence issues and can maximize spectrum efficiency. However, the spectrum allocated to LTE is limited, which cannot meet the growing demand for greater throughput from applications/services. Therefore, a new research project has been launched in 3GPP on extending LTE to utilize unlicensed spectrum in addition to the licensed spectrum. By definition, the unlicensed spectrum can be used simultaneously by multiple different technologies. Therefore, LTE needs to consider coexistence issues with other systems such as IEEE 802.11 (Wi-Fi). LTE operating in the unlicensed spectrum in the same manner as in the licensed spectrum may seriously degrade the performance of Wi-Fi because once Wi-Fi detects that the channel is occupied, it will not transmit.

Furthermore, one way to reliably utilize unlicensed spectrum is to send the necessary control signals and channels on the licensed carrier. That is, as shown in Figure 4, the UE is connected to the PCell in the licensed band and to one or more SCells in the unlicensed band. In this application, the secondary cell in the unlicensed spectrum is denoted as a Licensed Assisted Access Secondary Cell (LAASCell).

FIG4 illustrates Licensed Assisted Access (LAA) to unlicensed spectrum using LTE carrier aggregation.

Standalone LTE in unlicensed spectrum is discussed below.

A new industry forum has been launched to extend LTE to operate entirely on unlicensed spectrum in standalone mode, referred to in marketing as "MulteFire." No licensed carrier is used for basic control signaling and control channels. Therefore, all transmissions need to occur on unlicensed spectrum without guaranteed channel access availability, while also meeting regulatory requirements for unlicensed spectrum.

The use of carriers in unlicensed spectrum should be fair and equitable for different devices. One component of ensuring this fair sharing is the requirements for how transmissions are allocated across the system bandwidth. Here, the regulations typically include requirements for at least two different conditions/parameters, namely:

1. Occupied channel bandwidth

2. Maximum power spectral density (PSD)

For example, according to ETSI 301893, both parameters are mandatory for 5 GHz carriers, while the US regulations for 5 GHz only mandate the maximum PSD.

The occupied bandwidth requirement is expressed in the form that the bandwidth containing 99% of the signal power should be between 80% and 100% of the declared nominal channel bandwidth. The current understanding of this requirement is that it is tested (averaged) over a time interval exceeding one subframe (1ms). Therefore, the frequency allocation of a UE must vary between subframes in a way that meets this requirement. It remains an open question whether this requirement needs to be met for UEs that transmit only in a single subframe (such as PRACH or with a single PUSCH).

Maximum PSD requirements exist for many different regions. In most cases, this requirement is expressed using a 1MHz resolution bandwidth. For example, the ETSI 301 893 specification requires 10dBm/MHz for the 5150-5350MHz band. The impact of PSD requirements on physical layer design is that, without proper design, signals with small transmission bandwidths will be limited in transmit power. This can negatively impact operational coverage. In other words, the maximum PSD requirement necessitates changes in the binding conditions for UL transmissions in unlicensed spectrum.

A LBT gap between an sPUCCH and a subsequent PUSCH subframe may be considered, where the sPUCCH is between 4 and 6 symbols long and follows a partial DL subframe. If there is no gap, there is an open question as to what the user should transmit during the sPUCCH scheduled only for PUSCH/ePUCCH in the next subframe.

In general, it should be noted that the term "unlicensed" or "unlicensed carrier" or "unlicensed spectrum" or "unlicensed bandwidth" may refer to a carrier/spectrum accessed using an LBT procedure, and unless specifically stated otherwise, the terms "LBT access", "LBT access carrier" or "LBT access spectrum", "LBT access bandwidth" may be used interchangeably with these terms anywhere in this disclosure. In this context, LBT access may refer to a bandwidth/carrier/frequency/spectrum that is accessible and/or access transmission (e.g., according to rules and/or standards) only after a successful LBT procedure has been performed, where a successful LBT procedure may allow access to transmission (i.e., allow transmission) for a given amount of time, which may be defined, for example, by a rule or standard. Specifically, this amount of time may cover the duration of one or more subframes (1 subframe of LTE has a duration of 1 ms).

The interleaving design for UL transmission is discussed below.

Interleaved transmissions can be thought of as a means of giving LAA (or generally, UL signals on a carrier/spectrum using LBT/channel sensing) UL signals a smaller BW, higher transmit power (and, to a lesser extent, meeting transmit BW requirements) when needed. Interleaved transmissions can be performed on a PRB (physical resource block) basis. In scenarios with large frequency offsets or with a delay spread greater than the cyclic prefix, subcarrier-based interleaving may result in transmissions that are subject to ICI (inter-carrier interference). This design is also known as block-interleaved FDMA (B-IFDMA).

Figure 5 shows an example interlace design with five interlaces for a 20 MHz system bandwidth (with a maximum of 100 RBs available for transmission). As shown in Figure 5 , a uniform spread of RBs, i.e., uniform interlace, can be considered, where each interlace contains 100/5 = 20 RBs. The right figure shows the first 1.2 MHz of the same allocation. The darker lines represent example boundaries of the PSD requirement measurement interval (1 MHz resolution bandwidth). The lighter stripes represent the allocated RBs for that interlace.

Figure 5 shows the allocation of a first interlace, which is an example design with 5 interlaces for a 20 MHz bandwidth (i.e., 100/5 = 20 RBs per interlace). The right figure shows the first 1.2 MHz of the same allocation. The darker lines represent the boundaries of the PSD requirement measurement interval (1 MHz resolution bandwidth). The light stripes represent the allocated RBs for that interlace.

In LAA/standalone LTE-U uplink, the SRS originally designed for LTE on licensed spectrum cannot be reused.

1. On unlicensed carriers, channel access (for transmission) operates based on the LBT mechanism. Channel access availability for transmitting SRS on unlicensed carriers cannot be guaranteed.

2. In licensed LTE, SRS is partially used for channel sounding to allow frequency-selective scheduling in the UL. To this end, the SRS is designed to span the entire bandwidth. In unlicensed bands with interleaved UL resource allocation, frequency-selective scheduling does not provide much gain because PUSCH transmissions from different UEs can be evenly distributed across the spectrum. Therefore, the SRS design for unlicensed carriers is mainly used to meet requirements such as UL MIMO sounding and uplink timing estimation.

The physical layer design of SRS for LBT access uplink transmission (particularly for LAA/standalone LTE-U uplink) disclosed in this disclosure includes several design options and examples. In the proposed design, SRS can be sent together with PUSCH signaling (e.g., to avoid additional LBT). SRS can occupy the last (SC-FDMA) symbol in the UL subframe, for example, where PUSCH interleaved on an RB basis spans the entire transmission bandwidth. In each interlace, SRS can be sent from different users/antenna ports via frequency division and/or cyclic shift multiplexing.

The methods described herein provide at least one of the following:

1. No additional LBT is required to enable SRS transmission on unlicensed carriers.

2. It can maintain functions similar to those of SRS in licensed LTE.

3. SRS Measurement and Multiple Subframe Grant Two aspects can benefit from placing the SRS in the last symbol of a subframe.

These methods will be explained in more detail by means of a number of exemplary embodiments.It should be noted that the proposed method can be applied to different variants of wireless communication systems, such as LTE operating in unlicensed spectrum (eg LAA and standalone LTE-UUL).

The following design options describe different examples of reference signal patterns in the context of LTE and using SRS. However, such patterns can be used for other (UL/SL) reference signaling over the LBT access bandwidth (e.g., in a MulteFire system where the functionality of an eNodeB can be provided by the access point).

Exemplary SRS design option 1 is described below.

To avoid additional LBT, SRS is transmitted only in the same subframe together with PUSCH, where PUSCH may span the entire bandwidth (eg, carrier, and/or bandwidth allowed and/or specified by regulations or standards) through interleaving.

As shown in Figure 6, within an interlace (e.g., interlace #0), the SRS occupies the last (SC-FDMA) symbol. In the frequency domain, the SRS spans the entire bandwidth (e.g., across the interlaces). The multiplexing of SRSs transmitted from multiple antenna ports and/or multiple users of each UE can be based on cyclic shifts (specifically, based only on cyclic shifts).

FIG6 shows an example of SRS design option 1.

Exemplary SRS design option 2 is described below.

In another option, within each subframe of an interlace, in addition to the cyclic shift, the SRS can be multiplexed in the frequency domain, that is, multiplexed in a comb manner (sent on every other subcarrier). An example is shown in Figure 7, where the SRS on even antenna ports is sent on even subcarriers and the SRS on odd antenna ports is sent on odd subcarriers (2-comb), or vice versa.

FIG. 7 shows an example of SRS design option 2. FIG.

Exemplary SRS design option 3 is described below.

In this option, which may be complementary to and/or based on Option 2, multiplexing within each subframe of an interlace through frequency division and cyclic shifting is highly flexible and configurable. For example, comb usage (i.e., subcarrier mapping per user or antenna port) may be configurable. Configuration information may be indicated by the eNodeB or access point in an UL grant and/or higher layer signaling. In another example, the comb usage factor may not be limited to 2 (occupying every other subcarrier). A higher comb usage factor (e.g., 4-comb) may be used to multiplex more users.

In general, multiplexing multiple users and/or antenna ports can be performed through various combinations of frequency division and cyclic shifting. For example, to multiplex four antenna ports within one interlace, two typical options are to use a 4-comb with no cyclic shift and a 2-comb with two different cyclic shifts for antennas 1/3 and 2/4, respectively.

Exemplary SRS design option 4 is described below.

In this option, each user/terminal's SRS transmission involves two interlaces, and a 2-comb is used in each interlace. As shown in Figure 8, the SRS is sent on the even subcarriers in the assigned interlace x (interlace #0 in the figure) and on the odd subcarriers in interlace mod (x+5, 10) (interlace #5 in the figure).

Alternatively, another example is that if x<5, SRS is transmitted on even subcarriers of interlace x and interlace mod (x+5, 10), and if x>=5, SRS is transmitted on odd subcarriers.

Note that if a UE is assigned half an interlace, its SRS will cover every PRB in the system BW. When two UEs are each assigned half an interlace, their SRS signals are multiplexed on all subcarriers in the channel BW.

The above design options can be extended to more general options. The SRS transmission for each user/terminal can involve m (>= 2) interlaces, and n (>= 2) combs can be used in each interlace. In one example, multiplexing occurs only in the frequency domain, that is, the SRS for each user/antenna port is transmitted on a specific set of interlaces and a specific comb in each such interlace. The configuration of this SRS transmission is flexible. In another example, in addition to the last example, cyclic shifts can be used to further enhance multiplexing capacity.

FIG8 shows an example of SRS design option 4.

An exemplary SRS design option 5 is described below.

This option addresses what users should send that do not have ACK/NACK or CSI transmissions in the MulteFire sPUCCH and are scheduled for PUSCH or ePUCCH transmissions immediately following the sPUCCH. As an example, users sending feedback in the sPUCCH and users scheduled in the UL subframe after the sPUCCH can both perform UL LBT before the start of the sPUCCH, and there is no additional LBT gap between the sPUCCH and the next UL subframe. In this case, the SRS is used as the initial signal by users/terminals that do not send feedback during the sPUCCH. In addition to MIMO sounding, the SRS can also be used at the eNB for timing and frequency estimation.

FIG9 shows SRS in sPUCCH.

A non-limiting example is shown in FIG9 , where the SRS signal is repeated in time across the sPUCCH region on a pre-specified interlace with the same cyclic shift in all four symbols. All users not sending feedback in the sPUCCH can be assigned the same interlace for their initial SRS-based signal. In another case, a different cyclic shift or comb can be configured in each symbol for a specific user. In other examples, the frequency domain allocation of the SRS can be based on one or more of the previously described SRS design options.

Figure 10 schematically illustrates a terminal 10, which in this example may be implemented as a user equipment. Terminal 10 includes control circuitry 20, which may include a controller connected to a memory. A receive module, a transmit module, a control or processing module, a CIS receive module, and/or a scheduling module may be implemented in and/or executed by control circuitry 20, specifically as modules within the controller. Terminal 10 also includes radio circuitry 22, which provides receive and transmit or transceiver functionality and is connected or connectable to the control circuitry. Antenna circuitry 24 of terminal 10 is connected or connectable to radio circuitry 22 for collecting, transmitting, and/or amplifying signals. Radio circuitry 22 and control circuitry 20 controlling it are configured for cellular communication with a network, specifically utilizing E-UTRAN/LTE resources as described herein, on a first cell/carrier and a second cell/carrier. Terminal 10 may be adapted to perform any of the methods for operating a terminal disclosed herein; specifically, it may include corresponding circuitry, such as control circuitry.

Figure 11 schematically illustrates a network node or base station 100, which may specifically be an eNodeB or a MuLTEFire access point. The network node 100 includes control circuitry 120, which may include a controller connected to a memory. A receiving module and/or a transmitting module and/or a control or processing module and/or a scheduling module and/or a CIS receiving module may be implemented in and/or executed by the control circuitry 120. The control circuitry is connected to control radio circuitry 122 of the network node 100, which provides receiver and transmitter and/or transceiver functionality. Antenna circuitry 124 may be connected or connectable to the radio circuitry 122 to provide signal reception or transmission and/or amplification. The network node 100 may be adapted to perform any of the methods disclosed herein for operating a network node; in particular, it may include corresponding circuitry, such as control circuitry.

This disclosure describes several options for SRS design for SRS transmission on unlicensed carriers. The SRS can occupy the last multicarrier symbol (i.e., the last OFDM/B-IFDMA symbol), for example, in each UL subframe or interlace subcarrier. The proposed design options describe various mechanisms for multiplexing SRS transmitted from different users/antenna ports.

In general, a terminal for a wireless communication network may be considered. The terminal may be adapted to and/or include an LBT module for performing an LBT procedure and/or LBT access for one or more (transmission) bandwidths. The terminal may be adapted to and/or configured to and/or include a sending module for sending reference signaling via the bandwidth, specifically based on a (successful) LBT procedure and/or LBT access performed with respect to the bandwidth. This sending may be based on a configuration. The terminal may be adapted to be configured and/or include a configuration module for configuring accordingly.

A method for operating a terminal in and/or within a wireless communication network may be considered. The method may include performing an LBT procedure and/or LBT access for one or more (transmission) bandwidths. Generally, the method may include sending reference signaling via (transmission bandwidth) based specifically on a (successful) LBT procedure and/or LBT access performed with respect to the bandwidth. The sending may be based on a configuration. The method may include, for example, receiving a corresponding configuration from a network node.

A network node for a wireless communication network may be considered. The network node may be adapted to and/or include a configuration module for configuring a terminal with a configuration for sending reference signaling. Specifically, the configuration may involve reference signaling on a (transmission) bandwidth accessed and/or accessible (to the terminal) based on a (successful) LBT procedure or access performed by the terminal. The network node may be adapted to and/or include a receiving module for receiving reference signaling based on the configuration. Alternatively or additionally, the network node may be adapted to and/or include an estimation module for estimating channel conditions based on the received reference signaling.

Furthermore, a method for operating a network node of a wireless communication network and/or a network node in a wireless communication network may be contemplated. The method may include configuring a terminal with a configuration for transmitting reference signaling. Specifically, the configuration may relate to reference signaling on a (transmission) bandwidth accessed and/or accessible (to the terminal) based on a (successful) LBT procedure or access performed by the terminal. The method may include receiving the reference signaling based on the configuration. Alternatively or additionally, the method may include estimating channel conditions based on the received reference signaling.

Reference signaling may generally include one or more reference signals (specifically, SRS). A reference signal may generally be considered to cover and/or appear in (only) one resource element and/or be defined as (only) one resource element. Multiple reference signals may cover and/or appear in more than one resource element, which may be arranged in a (reference signal) pattern in one or more interlaces and/or transmission bandwidths.

The sending of reference signaling may be part of and/or include the following: interleaving bandwidth and/or using a coverage bandwidth and/or including one or more interlaces within a bandwidth. Alternatively or additionally, the sending of reference signaling may be performed based on a (reference signal) pattern. The sending of reference signaling may be on the sidelink and/or uplink.

The pattern, in particular the reference signal pattern and/or the interleaving pattern, can be configurable and/or configuration-based. The configuration can be configured by a network node, such as an eNodeB, which can be a node that is an intended receiver of the reference signaling. The reference signal pattern can be a comb pattern and/or one of the patterns described herein (particularly with respect to designs 1 to 5).

There may be different reference signaling patterns for different interlaces, eg, based on the corresponding configuration.

A reference signal of a pattern may typically be associated with the last symbol of a time structure such as a subframe for (UL) transmission, for example, if the reference signal is transmitted or is to be transmitted in a subcarrier/resource element. A signal associated with a time unit (e.g., a symbol) may mean that the signal is transmitted at a time or time interval associated with and/or defined by the time unit or symbol.

A comb may be considered as a pattern that may define an arrangement (particularly with respect to frequency) wherein between (every) two subcarriers/resource elements where a reference signal is transmitted/to be transmitted there is at least one subcarrier/resource element (in the frequency domain) that is used for transmission of other signaling, e.g. for channel transmissions, in particular transmissions on PUCCH (Physical Uplink Control Channel), sPUCCH (shortened PUCCH, for shortened transmission time intervals), ePUCCH (enhanced PUCCH), PUSCH, etc. Alternatively, a comb may define an arrangement wherein between every two subcarriers/resource elements where a reference signal associated with a (first) antenna element or antenna port or antenna subarray or virtual antenna is transmitted/to be transmitted there is at least one subcarrier/resource element (in the frequency domain) that is used for transmission of reference signaling associated with at least one other (second) antenna element or antenna port or antenna subarray or virtual antenna transmission.

Typically, a comb may define a pattern where one or more other subcarriers/REs for other signaling are arranged between two adjacent (having the closest distance to each other in terms of frequency) subcarriers/REs for reference signaling, where the other signaling may include signaling on a specific channel utilizing different/other antenna sub-arrangements and/or reference signaling.

For n-comb, between two subcarriers and/or resource elements used for sending and/or allocated for reference signaling (associated with a (first) antenna element/port/subarray or virtual antenna), there may be n-1 other subcarriers/resource elements. The other subcarriers/resource elements may refer to subcarriers/resource elements associated with different kinds of signaling and/or different antenna sub-arrangements and/or different antenna ports. An antenna sub-arrangement may refer to a sub-division of an antenna arrangement or antenna array, where a sub-arrangement may include (physical) antenna elements, a sub-array 8 that may have one or more physical antenna elements and/or virtual antennas (that may be associated with one or more physical antenna elements), and/or may involve associated antenna ports. An antenna port may generally be an interface for providing signals to an antenna sub-arrangement for transmission using the (physical) antenna elements of the antenna sub-arrangement. The antenna port may be considered to provide a mapping of signaling (in particular reference signaling) to antenna elements.

For example, a scheduling pattern may be configured. The scheduling and/or allocation pattern may include and/or correspond to a pattern configured for a terminal. A pattern may generally refer to resources used for uplink and/or sidelink transmissions. Different patterns may be configured for different interlaces of the transmission bandwidth. A bandwidth may include and/or be covered by multiple interlaces.

Performing a bandwidth-related LBT procedure and/or LBT access may refer to performing an LBT procedure or access to access bandwidth for transmission.

The reference signaling may include one or more reference signals (particularly SRS).

The configuration may generally indicate and/or specify a pattern, such as a reference signal pattern and/or an interleaving pattern, and/or schedule and/or allocate (uplink and/or sidelink) resources accordingly. It is worth noting that when using the LBT process, resources allocated solely for transmission and/or configured accordingly do not allow or necessarily make resources available for transmission.

A network node may be considered to be adapted to perform any one of the methods described herein for operating a network node.

A terminal may be considered to be adapted to perform any one of the methods described herein for operating a terminal.

A wireless transmitter can be a terminal or a network node.

A program product comprising a code executable by a control circuit is also disclosed. Specifically, if executed on a control circuit (which may be a control circuit of a terminal or a network node as described herein), the code causes the control circuit to perform and/or control any of the methods for operating a terminal or a network node as described herein.

Furthermore, a carrier medium is disclosed that carries and/or stores at least any one of the program products described herein and/or code executable by a control circuit, the code causing the control circuit to perform and/or control at least any one of the methods described herein. Generally, the carrier medium can be accessed and/or read and/or received by the control circuit. The stored data and/or program product and/or code can be considered part of the carrier medium. The carrier medium can generally include a guide/transmission medium and/or a storage medium. The guide/transmission medium can be suitable for carrying and/or transporting and/or storing signals, particularly electromagnetic signals and/or electrical signals and/or magnetic signals and/or optical signals. The carrier medium (particularly the guide/transmission medium) can be suitable for guiding and carrying these signals. The carrier medium (particularly the guide/transmission medium) can include an electromagnetic field (e.g., radio waves or microwaves) and/or an optically transmissive material (e.g., fiberglass and/or cable). The storage medium can include at least one of a volatile or non-volatile memory, a buffer, a cache, an optical disk, a magnetic storage device, a flash memory, and the like.

(Transmission) bandwidth may refer to a frequency range or frequency band or spectrum that can be accessed for transmission based on LBT (particularly based on a successful LBT process). The bandwidth may cover a continuous frequency range from a lower boundary frequency to an upper boundary frequency. The width (in frequency) of the bandwidth or frequency band or spectrum and/or the frequency (range) covered by the bandwidth or frequency band or spectrum may be defined and/or based on rules and/or standards. Specifically, in frequency, the bandwidth may cover multiple subcarriers and/or resource blocks (respectively, carriers). It may be considered that the bandwidth may be allocated to a time/frequency structure according to a standard such as LTE. The bandwidth may be assigned to a time structure such as a subframe structure and/or be divided into subframes and/or frequency units, for example, associated with resource blocks and/or resource elements. The (maximum) duration of transmission after successful LBT access and/or the bandwidth available for transmission may be defined by rules and/or standards. The actual transmission duration may depend on the amount of data to be transmitted. A successful LBT process and/or the execution of a backoff period or a non-transmission gap may be required between two transmission events.

The bandwidth can be interleaved so that only a portion of the bandwidth is used for transmission (if permitted under LBT). A portion of the bandwidth used for transmission can be assigned to a specific channel, in particular a physical channel such as PUSCH or PUCCH. Different portions of the bandwidth (and/or different bandwidths) can be assigned to different (physical) channels. The channels can be defined according to a standard, in particular according to LTE. The bandwidth can be covered by a (bandwidth) pattern. This pattern can describe/specify how portions of the bandwidth (e.g., subcarriers) used for transmission are used, for example, which portions of the bandwidth used for transmission are assigned to specific signals (e.g., reference signals such as SRS) and/or for other signaling (e.g., depending on the channel). This pattern can be based on a configuration configured by the network (in particular, a network node such as an eNodeB). Patterns related to reference signals (SRS) and/or patterns that describe the location of reference signals (SRS) within the bandwidth can be referred to as reference signal patterns. Different portions of the bandwidth can be allocated to different antenna elements/antenna ports/antennas (e.g., virtual antennas) for transmission, for example, in a MIMO system. Thus, resources within the bandwidth can be associated with different antenna elements and/or different antenna subarrays. The (reference signal) pattern may be superimposed on the interleaved pattern.

The terminal and/or network node may include and/or be connected or connectable (e.g., for transmission) to an antenna array, which may include one or more (physical) antenna elements. The (physical) antenna elements may be arranged (and/or configured or configurable) in different sub-arrays and/or virtual antenna elements.

In the context of the present description, wireless communication may be communication (particularly the transmission and/or reception of data) via electromagnetic waves and/or an air interface (particularly radio waves, for example in a wireless communication network and/or using a radio access technology (RAT)). The communication may involve one or more terminals connected to the wireless communication network and/or more than one node of the wireless communication network and/or in the wireless communication network. It is envisaged that the nodes in or for communication and/or in the wireless communication network, of or for the wireless communication network are adapted to communicate using one or more RATs (particularly LTE/E-UTRA). The communication may generally involve the sending and/or receiving of messages (particularly in the form of packet data). The messages or packets may include control and/or configuration data and/or payload data and/or represent and/or include a batch of physical layer transmissions. The control and/or configuration data may refer to data related to the process of communication and/or the nodes and/or terminals of communication. It may, for example, comprise in a header, for example, address data relating to the communication node or terminal and/or data about the transmission mode and/or spectrum configuration and/or frequency and/or coding and/or timing and/or bandwidth as data relevant to the process of communication or transmission.

Each node or terminal involved in the communication may include radio circuitry and/or control circuitry and/or antenna circuitry, which may be arranged to utilize and/or implement one or more radio access technologies. The radio circuitry of a node or terminal may generally be adapted for transmitting and/or receiving radio waves, and may in particular include a corresponding transmitter and/or receiver and/or transceiver that may be connected or connectable to the antenna circuitry and/or control circuitry. The control circuitry of a node or terminal (often referred to as processing circuitry) may include a controller and/or a memory that is arranged to be accessible by the controller for read and/or write access. The controller may be configured to control the communication and/or radio circuitry and/or provide additional services. The circuitry of a node or terminal (in particular, the control circuitry or processing circuitry, such as a controller) may be programmed to provide the functionality described herein. The corresponding program code may be stored in an associated memory and/or storage medium and/or hardwired and/or provided as firmware and/or software and/or in hardware. The controller may generally include a processor and/or a microprocessor and/or a microcontroller and/or an FPGA (field programmable gate array) device and/or an ASIC (application-specific integrated circuit) device. More specifically, it can be considered that the control circuit includes or can be connected or can be connected to a memory, which can be adapted to be accessible by the controller and/or the control circuit for reading and/or writing. The radio access technology can typically include, for example, Bluetooth and/or Wi-Fi and/or WiMAX and/or cdma2000 and/or GERAN and/or UTRAN and/or in particular E-Utran and/or LTE and/or NR. Communication can specifically include physical layer (PHY) transmission and/or reception, on which logical channels and/or logical transmission and/or reception can be imprinted or layered.

The wireless transmitter may be (or be included in) a node of a wireless communication network and/or may be implemented as a terminal and/or a user equipment and/or a network node and/or a base station and/or a relay node and/or generally any device suitable for communicating in a wireless communication network (particularly cellular communication).

A cellular network may include network nodes (particularly radio network nodes) that may be connected or connectable to a core network (e.g., a core network having an evolved network core, such as that according to LTE or NR). The network nodes may, for example, be base stations. The connection between the network nodes and the core network/network core may be based, at least in part, on a cable/landline connection. Operations and/or communications and/or exchanges of signals involving a portion of the core network (particularly layers above a base station or eNB) and/or through a predefined cell structure provided by the base station or eNB may be considered to be of a cellular nature or referred to as cellular operation. Operations and/or communications and/or exchanges of signals that do not involve layers above a base station and/or do not utilize a predefined cell structure provided by a base station or eNB may be considered to be D2D communications or operations (particularly if they utilize radio resources provided and/or used for cellular operation, particularly carriers and/or frequencies and/or equipment (e.g., circuits such as radio circuits and/or antenna circuits, particularly transmitters and/or receivers and/or transceivers)). The network nodes may be considered to be implemented as access points, particularly MuLTEFire access points (MF access points).

The terminal can be implemented as a user equipment. A terminal or user equipment (UE) can generally be a device configured for wireless device-to-device communication and/or a terminal for a wireless and/or cellular network, specifically, a mobile terminal such as a mobile phone, smartphone, tablet, PDA, etc. If the user equipment or terminal takes over some control and/or relay functions of another terminal or node, the user equipment or terminal can be a node of a wireless communication network as described herein or a node for a wireless communication network. It is conceivable that the terminal or user equipment is suitable for one or more RATs (particularly LTE/E-UTRA or NR). The terminal or user equipment can generally have Proximity Services (ProSe) capabilities, which can mean that it is D2D capable or D2D enabled. The terminal or user equipment can be considered to include radio circuitry and/or control circuitry for wireless communication. The radio circuitry can include, for example, a receiver or receiver device and/or a transmitter or transmitter device and/or a transceiver device. The control circuitry can include a controller, which can include a microprocessor and/or a microcontroller and/or an FPGA (field programmable gate array) device and/or an ASIC (application-specific integrated circuit) device. It can be considered that the control circuit includes or can be connected or can be connected to a memory, which can be adapted to be accessible by the controller and/or control circuit for reading and/or writing.It can be considered that the terminal user equipment is configured to be a terminal or user equipment suitable for LTE/E-UTRAN.

A network node or base station can be any type of base station in a wireless and/or cellular network suitable for serving one or more terminals or user equipment. A base station can be considered a node or network node of a wireless communication network. A network node or base station can be suitable for providing and/or defining and/or serving one or more cells of the network, and/or allocating frequency and/or time resources for communication to one or more nodes or terminals of the network. In general, any node suitable for providing such functionality can be considered a base station. A base station, or more generally a network node (particularly a radio network node), can be considered to include radio circuitry and/or control circuitry for wireless communication. It is contemplated that a base station or network node can be suitable for one or more RATs (particularly LTE/E-UTRA or NR). The radio circuitry can include, for example, a receiver device and/or a transmitter device and/or a transceiver device. The control circuitry can include a controller, which can include a microprocessor and/or microcontroller and/or an FPGA (field programmable gate array) device and/or an ASIC (application-specific integrated circuit) device. The control circuitry can be considered to include or be connected or connectable to a memory, which can be suitable for being accessed by the controller and/or control circuitry for reading and/or writing. A base station can be arranged as a node of a wireless communication network (in particular, configured to be used for and/or enable and/or facilitate and/or participate in cellular communications, for example, as a directly involved device or as an assisting and/or coordinating node). Generally, a base station can be arranged to communicate with a core network and/or provide services to one or more user devices and/or control one or more user devices and/or relay and/or transmit communications and/or data between one or more user devices and the core network and/or another base station and/or have proximity service capabilities. For example, according to the LTE standard, an eNodeB (eNB) can be considered as an example of a base station. A base station can generally have proximity service capabilities and/or provide corresponding services. It can be considered that a base station is configured as an evolved packet core (EPC) or is connected or connectable to an evolved packet core (EPC) and/or provides corresponding functions and/or is connected to corresponding functions. The functions and/or multiple different functions of a base station can be distributed across one or more different devices and/or physical locations and/or nodes. A base station can be regarded as a node of a wireless communication network. Generally, a base station may be considered as being configured as a coordination node and/or specifically to allocate resources for cellular communication between two nodes of a cellular network, in particular two user equipments.

It can be considered that for cellular communication, for example, via and/or defining a cell that can be provided by a network node (in particular a base station or eNodeB), at least one uplink (UL) connection and/or channel and/or carrier and at least one downlink (DL) connection and/or channel and/or carrier are provided. The uplink direction can refer to the direction of data transmission from the terminal to the network node (for example, a base station and/or a relay station). The downlink direction can refer to the direction of data transmission from the network node (for example, a base station and/or a relay node) to the terminal. UL and DL can be associated with different frequency resources (for example, carriers and/or spectrum bands). A cell may include at least one uplink carrier and at least one downlink carrier that may have different frequency bands. A network node (for example, a base station or eNodeB) may be suitable for providing and/or defining and/or controlling one or more cells, for example, a PCell and/or a LA cell.

The network node (particularly a base station) and/or the terminal (particularly a UE) may be adapted to communicate in a spectrum band (frequency band) authorized and/or defined for LTE. In addition, the network node (particularly a base station) and/or the terminal (particularly a UE) may be adapted to communicate in a freely available and/or unlicensed/LTE unlicensed spectrum band (frequency band) (e.g., approximately 5 GHz).

An LBT carrier may refer to a carrier or cell on which an LBT procedure is to be performed before transmission, in particular in an unlicensed spectrum or frequency band. The expression LBT carrier may be used interchangeably with LA SCell or unlicensed cell or unlicensed carrier. A carrier may be associated with a spectrum and/or a frequency band and/or a channel. A cell may be associated with at least one channel or carrier; a cell may be considered to include different carriers or channels for uplink or downlink. For each direction of data transmission (uplink and downlink), a cell may include one or more frequency bands (e.g., subcarriers) and/or channels. There may be different numbers of channels or frequency bands for uplink and downlink.

The LBT process may generally refer to a process of determining whether a transmission may or is permissible (specifically, for a node or terminal performing LBT) to be sent in a given spectrum or frequency band or cell or carrier (specifically, a LA SCell or LBT carrier), and/or whether another transmission is in progress (which would indicate that its own transmission is not possible).

The LBT process may include monitoring a channel and/or spectrum and/or frequency band and/or carrier on which a transmission that may be intended may be performed (in particular, monitoring for transmissions from another source and/or transmitter), which may include receiving and/or detecting energy or power of transmissions or radiation in the channel and/or spectrum and/or frequency band. Failure of the LBT process may indicate that a transmission on the channel or cell or frequency band has been detected, which may be considered to be blocked by or for another transmitter (e.g., due to detection of a predetermined energy or power level). Failure of the LBT process may be considered equivalent to determining that the channel/spectrum/frequency band/carrier is busy.

A successful LBT process may indicate that the channel/spectrum/band/carrier is idle. Typically, the LBT process may be performed before a transmission and/or before a scheduled transmission. The LBT process may be considered to be performed on a frame-based and/or subframe-based basis and/or synchronously with the timing structure of the cell (particularly the PCell). The LBT process may include one or more CCA processes.

Listening and/or performing CCA may include determining and/or measuring the power and/or energy on the channel/spectrum/band/carrier being listened to (and/or performing CCA on) for a predetermined time. The measured power or energy may be compared to a threshold to determine a busy or idle state.

The storage medium may be suitable for storing data executable by the control circuit and/or computing device and/or storing instructions executable by the control circuit and/or computing device, which, when executed by the control circuit and/or computing device, cause the control circuit and/or computing device to perform and/or control any of the methods described herein. The storage medium may typically be computer-readable, such as an optical disk and/or magnetic storage and/or volatile or non-volatile memory and/or flash memory and/or RAM and/or ROM and/or EPROM and/or EEPROM and/or buffer memory and/or cache memory and/or database.

Resources or communication resources or radio resources may generally be frequency and/or time resources (which may be referred to as time/frequency resources). Allocated or scheduled resources may include and/or refer to frequency-related information (in particular, information about one or more carriers and/or bandwidths and/or subcarriers and/or time-related information, in particular, information about frames and/or time slots and/or subframes, and/or information about resource blocks and/or time/frequency hopping information). Allocated resources may particularly refer to UL resources (e.g., UL resources for a first wireless device to transmit to a second wireless device and/or for a second wireless device). Sending and/or using the allocated resources on the allocated resources may include sending data on the allocated resources (e.g., on the indicated frequency and/or subcarrier and/or carrier and/or time slot or subframe). In general, it may be considered that the allocated resources may be released and/or de-allocated. The network or a node of the network (e.g., an allocation or network node) may be adapted to determine and/or send corresponding allocation data indicating the release or de-allocation of resources to one or more wireless devices (in particular, the first wireless device).

Allocation data may be considered to be data that schedules and/or indicates and/or grants resources allocated by a control or allocation node (in particular, data that identifies or indicates which resources are reserved or allocated for communication by a wireless device or terminal and/or which resources a wireless device or terminal may use for communication) and/or data that indicates the granting or releasing of resources (in particular, with respect to uplink and/or downlink resources). Grants or resource or scheduling grants or scheduling data (in particular, which may relate to information about and/or represent and/or indicate resource scheduling) may be considered an example of allocation data. Allocation data may in particular include information and/or instructions about and/or for configuring a terminal, for example, indicating a measurement configuration to be used. It may be considered that the allocation node or network node is adapted to send the allocation data directly to the node or wireless device and/or indirectly to the node or wireless device via a relay node and/or another node or base station.

The allocation data may include control data and/or be part of a message or form a message (in particular, according to a predefined format, such as a DCI format, which may be defined in a standard (e.g., LTE)). The allocation data may include configuration data, which may include instructions for configuring and/or setting the user equipment to, for example, a specific operating mode (in particular, a measurement mode) related to the use of a receiver and/or a transmitter and/or a transceiver and/or regarding the use of a transmission (e.g., TM) and/or reception mode, and/or the allocation data may include scheduling data (e.g., permitted resources to be used for transmission and/or reception and/or indicated resources). A scheduling assignment may be considered to represent scheduling data and/or be considered an example of allocation data. A scheduling assignment may particularly relate to and/or indicate resources to be used for communication or operation. The configuration or allocation data may include instructions for configuring the terminal to perform interleaving (in particular, available resources on which interleaving may be performed), such as an interleaving set and/or how to interleave and/or a mapping for interleaving and/or a frequency range on which interleaving is performed, wherein the frequency range may correspond to the frequency range covered by the interleaving set.

Configuring a terminal, wireless device, or node may include instructing and/or causing the terminal, wireless device, or node to change its configuration, such as at least one setting and/or register entry and/or operating mode. The terminal, wireless device, or node may be adapted to configure itself, for example, based on information or data in a memory of the terminal or wireless device. Configuring a node, terminal, or wireless device by another device, node, or network may refer to and/or include sending information and/or data and/or instructions, such as allocation data, configuration data, and/or scheduling data and/or scheduling grants, to the wireless device or node by another device, node, or network. Configuring a terminal may include sending allocation data to the terminal indicating which modulation and/or coding to use. The terminal may be configured with and/or configured to schedule data and/or use scheduled and/or allocated uplink resources, such as for transmission, and/or use scheduled and/or allocated downlink resources, such as for reception. Uplink resources and/or downlink resources may be scheduled using allocation or configuration data, and/or the uplink resources and/or downlink resources may be provided with allocation or configuration data.

The first cell may typically be a cell of a licensed cellular network (eg, LTE), and may be a PCell and/or cell intended to carry control and command information, particularly for the PCell and/or the second cell (eg, LA SCell).

The second cell and/or the second uplink carrier (respectively, the second downlink carrier) may generally be a cell and/or uplink carrier (respectively, downlink carrier) of an unlicensed network and/or a cell and/or uplink carrier (respectively, downlink carrier) on which an LBT procedure must be performed/has been performed before data transmission, specifically, a LASCell. Control information/scheduling for the second cell may be sent on the first cell, for example, to provide authorization-assisted control and scheduling.

An uplink carrier may generally be or indicate a carrier and/or frequency band that is intended and/or used for uplink transmissions.

A downlink carrier may generally be or indicate a carrier and/or frequency band that is intended and/or used for downlink transmissions.

A carrier may typically be an unlicensed carrier and/or be accessed for transmission based on and/or after a successful LBT procedure. A channel may typically be a physical channel and/or be defined by comprising and/or being associated with one or more (radio and/or time/frequency) resources, in particular resource elements or resource blocks.

Interleaving may generally comprise transmitting on resources such that a transmitting device transmits on frequencies or frequency resources separated by one or more frequency units (e.g., minimum frequency units, or in particular, frequency ranges covered by a resource block). A separation unit may be a frequency unit on which a wireless transmitter does not transmit (except for undesired leakage or interference that may occur for physical reasons). In general, interleaving may specifically relate to an interleaving defined with respect to a resource block (respectively, a corresponding frequency range covered by an RB). Interleaving may comprise transmitting one or more interleavings and/or transmitting on one or more interleavings.

Typically, interleaving may comprise mapping and/or scheduling one or more interleavings on resources (which may be scheduled resources). The scheduled resources may be scheduled and/or configured by a wireless transmitter, e.g. for downlink or uplink transmissions. The scheduled resources may relate to one or more resource units (in particular resource blocks) and/or cover multiple frequency units (e.g., carriers (including multiple subcarriers)). For uplink transmissions, the scheduled resources may be configured by another wireless transmitter (e.g., a network node). The mapping may typically be performed by the wireless transmitter itself, e.g., based on the scheduled resources, e.g., the network node or terminal may perform the mapping itself (e.g., via a mapping module). Alternatively, the mapping may be performed by a configuring transmitter (e.g., a network node) (in which case the mapping may be indicated via allocation and/or configuration data, and/or the interleaving may comprise sending according to the scheduled resources and/or based on the indicated mapping).

An interleaving with respect to a frequency structure and/or associated resource structure may be defined such that the interleaving includes and/or covers a plurality of frequency units (and/or associated resource units), e.g., Nu units, where one unit is used and/or may be used for transmission, and one or more other units (e.g., Nu-1) are not used for transmission. Specifically, these units may be resource blocks. For example, Nu may be 6 or greater.

The frequency units of the interleaving may be continuous and/or contiguous in frequency. It may be considered that interleaving is generally defined with respect to frequency width rather than a specific frequency range (although different interleavings may be defined for different frequency ranges (e.g., due to different rule-defined guard intervals), and/or a specific interleaving may be defined and/or the interleaving structure may be mapped to a specific frequency range). In particular, interleaving may cover a continuous or contiguous frequency range, which may be referred to as an interleaving range.

The frequency units of an interleave used for transmission may be referred to as transmission units, and other units may be referred to as non-transmission units. The interleave units may specifically be resource blocks, and the frequency units may correspond to frequency ranges associated with the resource blocks. Generally, interleaving may include transmitting one or more interlaces (e.g., consecutive and/or contiguous interlaces), and thus may include transmitting over a number of transmission units corresponding to the number of interlaces.

It can be considered that for an interlace, the transmission units are located at one of the boundaries of the frequency range covered by the interlace, for example, at the highest or lowest frequency of the interlace. The same arrangement of transmission units in an interlace can be used for different interlaces (covering different frequency ranges) to perform interleaving. It can be considered that the transmission units of an interlace are arranged so that each guard interval (e.g., of the system bandwidth) includes at most one transmission unit (transmission resource block).

Since transmission units (frequencies or resource units) and/or resources used for transmission or for transmission scheduling are aggregated between transmission units and/or resources that are not used for transmission or for transmission scheduling, an interlace or an interlace set (respectively corresponding to resources) can be considered to represent resource aggregation. In this context, arranging a single transmission unit or resource or more than one transmission unit or resource between frequency or resource units that are not for transmission scheduling (with respect to frequency units such as adjacent frequencies or subcarriers) can be considered to be clustering. In general, clustering can at least partially involve arranging transmission units (particularly subcarriers) to be discontinuous (at least on one side) with other transmission units over a frequency range (particularly over a range covered by one or more resource blocks).

Scheduling resources and/or resource allocations may indicate and/or include an interleaving pattern. A resource or allocation may be a transmission resource (particularly an uplink transmission resource) and/or may be associated with or allocated to a specific device, such as a wireless transmitter such as a terminal (which may have been allocated resources by a network node such as an eNodeB or a network node that may have allocated resources to itself). The pattern may include one or more interleaving sets. One or more (particularly each) sets and/or patterns may be periodic and/or quasi-periodic in terms of the location and/or arrangement of resources on a transmission unit (particularly a subcarrier) or frequency. The sets and/or patterns may be considered block-wise periodic or quasi-periodic. Block-wise (quasi-)periodicity may mean that a specific pattern of transmission units (particularly subcarriers) is repeated multiple times (two or more times, particularly five or more times) within a frequency range (in the frequency domain). If the repetition pattern only covers a portion of the interleaving pattern of the scheduling resources or resource allocation, the (quasi-)periodicity may be considered block-wise.

The interleaving pattern may include multiple repetition patterns, in particular block-like repetition patterns. The individual repetition patterns may be different. The repetition pattern may be associated with and/or depend on the interleaving and/or interleaving set included in the interleaving pattern. The interleaving pattern may generally be defined and/or configured based on an interleaving indication or an interleaving set indication (which may be represented by configuration data or allocation data). The repetition pattern may be considered quasi-periodic if one or more transmission units (in particular subcarriers) are slightly shifted from the periodicity in the frequency domain. The slight shift may be a shift of one or two widths of the transmission unit width (in particular subcarrier width) up or down, and/or a shift of a distance (in the frequency domain) less than 10% or 5% of the total frequency range covered by the repetition pattern. A periodic or quasi-periodic repetition pattern may have an aggregation of adjacent or consecutively arranged transmission units (in particular subcarriers or blocks or aggregations of subcarriers) or transmission units that are equidistantly arranged (with respect to the frequency domain). The distance in the frequency domain may be, for example, a frequency or frequency unit, in particular in a subcarrier (and/or minimum frequency unit).

Interleaving may generally include performing DFT-OFDM modulation on the signal to be transmitted (particularly based on scheduled resources or resource allocations), which may include or indicate an interleaving pattern. Performing modulation may include and/or be based on, for example, RB to subcarrier mapping of a QAM modulated signal. DFT-OFDM modulated signal on scheduled resources or resource allocations. Modulation may be aggregated modulation and/or DFT-S-OFDM (DFT-Spread-OFDM) modulation. Modulation may be performed as described herein. The wireless transmitter may be adapted to perform such modulation and/or include a modulation module for such modulation. If and/or when DFT-OFDM modulation is performed on aggregated resources, the DFT-OFDM modulation may be considered aggregated, for example, as an interleaving pattern as described herein.

An interleaving pattern may generally include and/or indicate one or more interleaving sets. The pattern may indicate or include frequency units (e.g., subcarriers) and/or resources that may be used for transmission and/or scheduled for transmission, such as resource blocks and/or one or more transmission units (e.g., subcarriers). The pattern may be indicated by configuration data and/or allocation data.

A wireless transmitter (in particular a network node) may be configured and/or adapted to be configured and/or include a configuration module for configuring one or more wireless transmitters (e.g., terminals) to perform interleaving and/or transmit using an interleaving set, for example by allocating or configuring resources corresponding to the interleaving set to the terminal, for example by sending corresponding configuration or allocation data.

Performing interleaving and/or transmitting based on a frequency structure and/or a resource structure may mean following and/or utilizing the structure when transmitting.

Interleaving and/or transmitting (particularly in the context of interleaving) may comprise performing an LBT procedure and/or may depend on a successful LBT procedure, for example, an LBT procedure for an interleaving of a transmission unit and/or comprising a transmission unit. Interleaving and/or transmitting (particularly in the context of interleaving) may comprise transmitting such that, in each transmission unit/transmission resource block of the interleaving, the transmission is performed using a maximum allowed power or PSD for the guard interval and/or a power up to which the maximum allowed power or PSD is reached. Interleaving or transmitting may be considered to comprise transmitting such that, averaged over a predetermined number of time units (e.g., time slots and/or subframes and/or time units associated with a resource structure or resource unit) in the interleaved transmission unit/transmission resource block, the transmission is performed using a maximum allowed power or PSD for the guard interval and/or a power up to which the maximum allowed power or PSD is reached. This maximum power/PSD may be defined as a requirement or condition for the guard interval in which the transmission units are arranged and/or covered by the interleaving.

A sounding reference signal may generally be a reference signal that may be provided, for example, to estimate channel state and/or channel quality and/or timing/synchronization. A receiver of such a reference signal may generally know the transmit power and/or expected timing of the reference signal and may be adapted to compare the transmit power with the received power for such estimation.

A reference signal (particularly an SRS) can be considered an uplink signal that can be used for a network node such as an eNodeB and/or a sidelink signal that can be used for another terminal. The network and/or the network node can be adapted to configure the transmission power of the terminal that sends the reference signal/SRS, and/or the transmission power can be defined by a standard. There may be different kinds of reference signals/SRS, for example, cell-specific signals or terminal/UE-specific signals. The terminal can be configured for reference signal/SRS transmission, and/or a network node such as an eNodeB can be adapted for and/or perform such configuration. Configuring for reference signal transmission can include configuring timing (for example, in which time structure such as a subframe or time slot the SRS is to be sent), and/or transmission frequency (the frequency at which the transmission is performed/the time interval in which the transmission is to be performed) and/or the resources used for the transmission (resource elements).

A resource element can be considered as a form of time/frequency resources, in particular, the smallest unit defined for such resources. A resource element may specifically include a subcarrier (in the frequency domain) and a symbol (in the time domain).

Some useful abbreviations include:

Abbreviations explain

SRS Sounding Reference Signal

DMRS Demodulation Reference Signal

eNB evolved NodeB, base station

UE User Equipment

UL Uplink

LAA Authorized Assisted Access

RS reference signal

Scell secondary cell

LBT Listen before speaking

LTE-U LTE in unlicensed spectrum

PUSCH Physical Uplink Shared Channel

PUCCH Physical Uplink Control Channel

Carrier Aggregation (CA)

CoMP coordinated multipoint transmission and reception

CQI Channel Quality Information

CRS Cell-specific reference signal

CSI Channel State Information

CSI-RS CSI reference signal

D2D device to device

DL Downlink

EPDCCH Enhanced Physical DL Control Channel

DL Downlink; generally refers to the transmission of data to nodes/directions further away from the network core (physically and/or logically); in particular, from a base station or eNodeB to a D2D-enabled node or UE; often uses a different designated spectrum/bandwidth than the UL (e.g., LTE)

eNB Evolved NodeB; a form of base station, also known as eNodeB

E-UTRA/N Evolved UMTS Terrestrial Radio Access/Network, example of a RAT

FDD Frequency Division Duplex

ID

L1 Layer 1

L2 Layer 2

LTE Long Term Evolution, telecommunications standard

MAC Media Access Control

MBSFN Multi-Broadcast Single Frequency Network

MDT Minimized Drive Test

NW Network

OFDM Orthogonal Frequency Division Multiplexing

O&M Operations and Maintenance

OSS Operation Support System

PC Power Control

PDCCH Physical DL Control Channel

PH Power Headroom

PHR Power Headroom Report

PSS Primary Synchronization Signal

PUSCH Physical Uplink Shared Channel

R1, R2, ..., Rn resources, in particular time-frequency resources, in particular resources assigned to the corresponding carriers f1, f2, ..., fn

RA Random Access

PACH Random Access Channel

RAT Radio Access Technology

RE resource element

RB Resource Block

RRH Remote Radio Head

RRM Radio Resource Management

RRU Remote Radio Unit

RSRQ Reference Signal Received Quality

RSRP Reference Signal Received Power

RSSI Received Signal Strength Indicator

RX Receiver, receive related

SA Scheduling Assignment

SL sidelink, involving D2D transmission (device to device) between terminals, can be supported by the network or independent of the network; SL can use UL carrier/bandwidth (especially FDD)

SINR/SNR Signal to Noise and Interference Ratio; Signal to Noise Ratio

SFN Single Frequency Network

SON self-organizing network

SSS Secondary synchronization signal

TPC Transmit Power Control

TX Transmitter, transmission related

TDD Time Division Duplex

UE User Equipment

UL Uplink; typically the transmission of data to a node/direction that is closer to the network core (physically and/or logically); in particular, from a D2D-enabled node or UE to a base station or eNodeB; in the context of D2D, it can refer to the spectrum/bandwidth used for transmission in D2D, which can also be used for UL communications to an eNB in cellular communications; in some D2D variants, transmissions of all devices involved in D2D communications can typically be in the UL spectrum/bandwidth/carrier/frequency.

These abbreviations may be interpreted according to LTE or related standards.

Claims (5)

1. A terminal for a wireless communication network, comprising a processor and a memory, the memory storing a computer program that, when executed by the processor, causes the terminal to: Perform a Listen-Before-Speak (LBT) procedure for one or more transmission bandwidths; Transmit PUSCH signaling in one or more interleaved Physical Uplink Shared Channel (PUSCH) subframes within one or more transmission bandwidths; and Transmit probe reference signaling on one or more interleavings in the PUSCH subframe, wherein transmitting probe reference signaling includes: multiplexing probe reference signaling transmitted on different antenna ports based on cyclic shift. 2. A method for operating a terminal in a wireless communication network, comprising: Perform a Listen-Before-Speak (LBT) procedure for one or more transmission bandwidths; Transmit PUSCH signaling in one or more interleaved physical uplink shared channel (PUSCH) subframes within one or more transmission bandwidths, and Transmit probe reference signaling on one or more interleavings in the PUSCH subframe, wherein transmitting probe reference signaling includes: multiplexing probe reference signaling transmitted on different antenna ports based on cyclic shift. 3. A network node for wireless network communication, comprising a processor and a memory, the memory storing a computer program that, when executed by the processor, causes the network node to: Channel conditions are estimated based on probe reference signaling received from at least one terminal, wherein receiving the probe reference signaling includes: receiving PUSCH signaling in one or more interleaved Physical Uplink Shared Channel (PUSCH) subframes, and Probe reference signaling is received on one or more interleavings in the PUSCH subframe, wherein probe reference signaling transmitted on different antenna ports and/or by different users is multiplexed based on cyclic shift. 4. A method for operating a network node in a wireless communication network, the method comprising: estimating channel conditions based on probe reference signaling received from at least one terminal, wherein receiving the probe reference signaling comprises: receiving PUSCH signaling in a Physical Uplink Shared Channel (PUSCH) subframe on one or more interleavings, and receiving probe reference signaling on the one or more interleavings in the PUSCH subframe, wherein probe reference signaling transmitted on different antenna ports and/or by different users is multiplexed based on cyclic shift. 5. A computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform and/or control the method according to claim 2 or 4.