Communication method and device for channel sounding

Abstract

A communication device which can achieve full-band sounding while avoiding channel aging even on power-saving condition is disclosed. The communication device includes: a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid; and at least one processor configured to: generate configuration information for reference signal transmission of the another communication device, wherein different sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and send the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver.

Description

COMMUNICATION METHOD AND DEVICE FOR CHANNEL SOUNDING

[0001] The present invention relates to techniques for channel sounding in a wireless communication channel.Background

[0002] A typical wireless communication channel between a transmitter and a receiver may be represented by a random time-varying channel impulse response, a detailed description of which can be found in NPL (Non patent literature) 1. To expound a little more, a single pulse transmitted over a multipath wireless channel may be received as a train of pulses, wherein each pulse in the train denotes one multipath component. Each multipath component may experience events like reflection, refraction or scattering from the surrounding scatterers in the transmission path, thus undergo phase changes, leading to their constructive or destructive addition at the receiver. Such a phenomenon may be called multipath fading.

[0003] The knowledge of the instantaneous channel condition can be exploited effectively to improve communication performance. More specifically, the capacity of the fading channel may depend on the knowledge about the time-varying wireless channel at the transmitter and / or receiver. For example, the channel information at the transmitter is extremely useful for employing performance enhancing techniques, including but not limited to, power allocation, beamforming or scheduling operations.

[0004] Acquiring knowledge about the time-varying channel can be done by a method like channel estimation. In one such method, a reference signal (for example, a sounding reference signal (SRS)) already known to a receiver may be transmitted by a transmitter, enabling the receiver to compute the channel transfer function, more specifically, impulse response or frequency response of the channel.

[0005] In one exemplary form of communication, signal transmission and reception between a base station (BS) and a mobile user equipment (UE) may be considered. A BS may also be referred to as a gNodeB or eNodeB in some places and contexts in this disclosure. In such a scenario, the signal transmission from the UE to BS may be called as uplink (UL) communication, while that from the BS to the UE may be called downlink (DL) communication. It is known that in the time division duplex (TDD) method, the UL communication channel and the DL communication channel may follow channel reciprocity, thus enabling the estimated channel response of UL channel be exploited for DL transmission. Not restricted to TDD, there may be techniques to achieve channel reciprocity in frequency division duplex (FDD) method as well, for example, by employing a frequency correction algorithm based on channel characteristics, including but not limited to direction of arrival, channel covariance matrix or channel space-time correlation etc.

[0006] In a method of uplink channel sounding performed by the transmission of SRS from UEs to BS, the BS may instruct the UE about the time and frequency resources that should be used for SRS transmission. Such instructions may be provided by using a radio resource control (RRC) signaling. A UE receives the instructions from the BS about SRS resources, and may transmit SRS following the instructions. Appropriate SRS-resource allocation to a UE can improve channel estimation, resulting in precise beamforming.

[0007] SRS is a physical signal for uplink radio channel estimation. Furthermore, the use of SRS may also include beam management, codebook-based closed-loop spatial multiplexing, antenna switching, uplink timing estimation etc. An important use of SRS at the gNodeB is to find out the appropriate precoding for downlink transmission. SRS may be configured outside Physical Uplink Shared Channel (PUSCH), or across the whole bandwidth to obtain channel estimate at any frequency. Methods for generation and configuration of SRS is described in TS 38.211 Section 6.4.1.4 (NPL2). There can be periodic SRS, aperiodic SRS, and semi-persistent SRS as described in TS 38.331 Section 6.3 (NPL3). In an example of periodic SRS, an SRS configuration may be done by RRC signaling. Furthermore, in another example of aperiodic SRS, the triggering of SRS transmission may be done by downlink control information (DCI). As an example, PTL1 generally discloses a method for configuring aperiodic SRS using downlink control information (DCI).

[0008] SRS resource may mean the location of SRS symbols in the time and frequency grid. The sounding bandwidth of SRS for a particular UE can be determined by the parameters CSRSand BSRSaccording to NPL 2. For example, CSRSmay take a value from (0,1,…,63). Similarly, BSRSmay take one of the four values (0,1,2,3). According to NPL2, BSRSmay be given by the field b-SRS contained in the higher-layer parameter freqHopping if configured, otherwise BSRS=0. For a given (CSRS,BSRS) pair, the bandwidth and number of sub-bands for SRS transmission can be decided for a UE. In one example of “Table 6.4.1.4.3-1: SRS bandwidth configuration” in NPL 2, CSRS= 61 can be chosen. Then, the choice of BSRScan result in the following bandwidths and number of subbands. In this disclosure, the notations BSRSand b-SRS may be used interchangeably to indicate the same parameter. Similarly, the notations CSRSand c-SRS may be used interchangeably to indicate the same parameter. (Table 1)

[0009]

[0010] US 2023 / 0379118 A1

[0011] Goldsmith, Wireless Communications. Cambridge, U.K.: Cambridge Univ. Press, 20053GPP TS 38.211 v17.4.0 (2022-12). 3rd generation partnership project; Technical specification group radio access network; NR; Physical channels and modulation (Release 17).3GPP TS 38.331 v17.4.0 (2023-03). 3rd generation partnership project; Technical specification group radio access network; NR; Radio resource control (RRC) protocol specification (Release 17).Summary

[0012] Cell-edge UEs may not be able to perform full-band sounding in a single slot (i.e., using BSRS= 0) owing to their transmit power limitations. Thus, some UEs may need multiple slots to perform channel sounding by frequency hopping (i.e., using BSRS= 1, 2, 3). Since it takes multiple time slots to complete the sounding of full band when using BSRS= 1, 2, 3, hence part of the sounding result becomes obsolete till full band sounding is completed which can result in channel aging effects (and consequently inaccurate beamforming weight calculation for spatial multiplexing).

[0013] For such UEs that employ BSRS= 1, 2, 3, if the downlink data scheduling has to be done on the most recently sounded RBs only (to combat channel aging), then a smaller transport block may have to be adopted. A smaller transport block may result in lower coding gain as compared to longer transport block. If the most recently sounded sub-band in BSRS= 1, 2, 3 experience deep-fade, then they may have to be discarded and cannot be used for scheduling downlink data. In contrast, if full-band sounding is done in a single slot using BSRS= 0, then the channel condition over the entire bandwidth is known at once, thus enabling to discard the subcarriers in deep fade and still transmitting downlink data on the good subcarriers.

[0014] However, there may be drawbacks in BSRS= 0 as well. Performing channel sounding by employing BSRS= 0 may require high transmit power as SRS has to be transmitted across the whole band in a single OFDM symbol, and in particular, may be difficult for UEs that are located far away from the BS. Cell-center UEs that may be capable of performing full-band sounding in a single slot (i.e., using BSRS= 0) may not be able to perform interference randomization employing frequency-hopping since they sound the full channel in a single slot without hopping. Such interference randomization may be considered as a technique in 3GPP specification Release 18.

[0015] An object of the present invention is to solve the above-discussed technical problems, more specifically to provide techniques for channel sounding which can achieve full-band sounding while avoiding channel aging even on power-saving condition.

[0016] According to an aspect of the present disclosure, a communication device includes: a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid; and at least one processor configured to: generate configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and send the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver. According to another aspect of the present disclosure, a communication method of a communication device including a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid; and a controller, the communication method by the controller, includes: generating configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and sending the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver. According to a further aspect of the present disclosure, a communication method for radio resource control (RRC) signaling in a communication system including a base station and a user terminal, the method by the base station includes: configuring a sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration; and allocating the single combined configuration to the user terminal. According to a further aspect of the present disclosure, a program executed by a controller of a communication device including a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid, the program comprising a set of instructions for: generating configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and sending the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver. According to a further aspect of the present disclosure, a program executed by a controller of a base station for radio resource control (RRC) signaling, the program comprising a set of instructions for: configuring a sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration; and allocating the single combined configuration to a user terminal.

[0017] The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangement of parts that are adapted to affect such steps, all is exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims. In addition to the objects mentioned, other obvious and apparent advantages of the invention will be reflected from the detailed specification and drawings.

[0018] FIG. 1 is a diagram illustrating an operation of uplink transmission from a UE to a BS in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 2 is a diagram illustrating an operation of downlink transmission from BS to UE in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 3 is a diagram illustrating a BS according to an example embodiment of the present invention.FIG. 4 is a diagram illustrating a controller in the BS according to an example embodiment of the present invention.FIG. 5 is a diagram illustrating an example of UE specific SRS configuration for trigger type 0 (periodic or single SRS) in long term evolution (LTE) wireless communication system.FIG. 6 is a diagram illustrating an example of UE specific SRS configuration for trigger type 1 (aperiodic SRS) in LTE wireless communication system.FIG. 7 is a diagram illustrating an example of periodic SRS wherein the SRS parameters are highlighted.FIG. 8 is a diagram illustrating an example of different SRS bandwidth configurations.FIG. 9 is a schematic diagram illustrating an example of radio frame diagram in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 10 is a diagram illustrating an example of time-frequency resource grid for one RB and one time-slot in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 11 is a diagram illustrating another example of time-frequency resource grid for one RB and one time-slot in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 12 is a diagram illustrating an example of channel sounding according to an example embodiment of the present invention.FIG. 13 is a diagram illustrating another example of channel sounding according to an example embodiment of the present invention.FIG. 14 is a radio frame diagram illustrating an existing method of channel sounding.FIG. 15 is a radio frame diagram illustrating an example embodiment of the present invention.FIG. 16 is a flowchart illustrating the steps of SRS configuration at a BS according to an example embodiment of the present invention.FIG. 17 is a flowchart illustrating the steps of SRS configuration at a BS according to an example embodiment of the present invention.FIG. 18 is a diagram illustrating an example of SRS Resource in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 19 is a diagram illustrating a further detailed example of SRS Resource in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 20A is a diagram illustrating an abstract syntax notation (ASN) for SRS-ResourceSet in an example of SRS-Config Information element in a wireless communication system to which an example embodiment of the present disclosure is applied.FIG. 20B is a diagram illustrating the ASN for SRS-ResourceSet in the example of SRS-Config Information element.FIG. 20C is a diagram illustrating the ASN for SRS-Resource in the example of SRS-Config Information element.FIG. 20D is a diagram illustrating the ASN for SRS-Resource in the example of SRS-Config Information element.FIG. 20E is a diagram illustrating the ASN for SRS-Resource in the example of SRS-Config Information element.FIG. 20F is a diagram illustrating the ASN for SRS-Resource in the example of SRS-Config Information element.FIG. 20G is a diagram illustrating the ASN for SRS-PeriodicityAndOffset in the example of SRS-Config Information element.FIG. 20H is a diagram illustrating the ASN for SRS-PeriodicityAndOffset in the example of SRS-Config Information element.FIG. 20I is a diagram illustrating the termination of the example of SRS-Config Information element.FIG. 21 is a schematic diagram illustrating a method of SRS configuration according to an example embodiment of the present invention.FIG. 22A is a diagram illustrating an example of SRS Resource in a wireless communication system according to an example embodiment of the present invention.FIG. 22B is a diagram illustrating an example of SRS Resource in a wireless communication system according to an example embodiment of the present invention.FIG. 23 is another example embodiment of the present invention employing antenna switching.Detailed Description

[0019] 1. Outline of example embodiments of the present invention The technical problems of the background art as discussed above can be solved by the example embodiments of the present invention such that a communication device sends configuration information for reference signal transmission to another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information. More specifically, full-band channel sounding is performed in a single slot using frequency-hopping over multiple OFDM symbols in a single time-slot. As an example, a sub-band can be sounded in each OFDM symbol of a flexible slot or an uplink slot so that the sounding of full-band can be completed in multiple OFDM symbols but within a single flexible slot or an uplink slot.

[0020] This technique can perform full-band channel sounding in a single slot, similar to BSRS= 0. In the case where frequency hopping is employed, it can employ interference randomization based on frequency hopping which is otherwise impossible in background art of BSRS= 0. Furthermore, since SRS is transmitted in only a sub-band in each OFDM symbol, hence less transmit power is required resulting in power-saving. This also means that the proposed technique can be used by the cell-edge UEs as well as the cell-center UEs.

[0021] 1.1) Descriptions of terms Hereafter, the technical terms related to an SRS-based channel sounding will be described in advance of embodiments and examples of the present invention.

[0022] (SRS based beamforming) SRS-based beamforming is a method to achieve accurate spatial multiplexing in a multiuser multiple-input multiple-output (MIMO) communication system. More specifically, a UE may receive instructions from a BS about the SRS resources (for e.g., information including but not limited to time resource, frequency resource, hopping parameters etc.) and then the UE may transmit uplink SRS following the received instructions.

[0023] On receiving the SRS, the BS may be able to estimate the channel impulse response or frequency response from the received SRS, and then the channel estimate obtained in uplink may be used for downlink beamforming. For example, this may be possible owing to the channel reciprocity property of time division duplexing. The BS may compute beamforming weights for downlink transmission based on the channel estimate obtained from the SRS received in uplink. Accurate beamforming weight can result in precise spatial multiplexing in a multiuser MIMO system.

[0024] SRS-based channel sounding may be performed by different parameter configurations depending on the SRS related parameters instructed by the BS to the UE. For example, uplink channel sounding may be performed by transmission of SRS over the available bandwidth in one or more time slots. As described before, the full-band channel sounding requires high transmit power from the UE, thus may not be suitable for some UEs (for example cell-edge UEs). On the contrary, channel sounding of the full bandwidth can be performed by frequency hopping over multiple time-slots. Such sounding method can be supported by UEs with relatively low transmit power since only a part of the bandwidth is sounded in each hop.

[0025] (RRC signaling for SRS) SRS resource allocation may be done by a BS using RRC signaling. RRC signaling is a signaling protocol that is used for communication between network and UE in order to set up and manage a radio connection. More specifically, it uses logical channels and transport channels to exchange messages between UE and a gNodeB. Here, the logical channels may be comprised of broadcast, control and traffic channels. Furthermore, the transport channels may include uplink and downlink channels.

[0026] The RRC signaling may be used to configure all radio resources (physical (PHY), medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP)) to make a communication possible between UE and the gNodeB. The information element (IE) SRS-Config may be used for configuring SRS. Such a configuration may contain a list of SRS-Resources, a list of SRS-PosResources, a list of SRS-PosResourceSets and a list of SRS-ResourceSets.

[0027] RRC signaling may be based on three main stages, such as, connection setup, connection re-establishment, and connection release. In 5G new radio (NR), there may be three RRC states described as RRC inactive state, RRC idle state, and RRC connected state. Specifically, the state transition between RRC inactive state and RRC connected state may be expedited by storing the UE context at gNodeB and UE. It may be possible that the network or UE optionally stays in RRC inactive state without completing the release of RRC when there is no traffic so that it can quickly switch back to RRC connected state when necessary.

[0028] (SRS configuration) As described before by referring to TABLE 1, BSRS= 0 may refer to full-band sounding which means all 272 resource blocks (RBs) are sounded in a 100 MHz channel bandwidth. Similarly, BSRS= 1 may imply that the whole channel is sounded in two subbands where each subband consists of 136 RBs. BSRS= 2 would mean that only 136 RBs are sounded in two subbands wherein each subband consists of 68 RBs. Furthermore, BSRS= 3 would mean 68 RBs are sounded in 17 subbands wherein each subband consists of 4 RBs.

[0029] A parameter Bhopcan be selected from the values (0,1,2,3) which is the frequency hopping parameter for SRS. Such frequency hopping can be disabled by setting Bhop< BSRS.

[0030] A parameter nRRCdefined by higher-layer parameter ‘freqDomainPosition’ can be selected from (0,1,…,67) to determine a circular frequency-domain offset of the SRS. Another parameter nshiftdefined by higher-layer parameter ‘freqDomainShift’ can be selected from (0,1,…,271) for frequency-domain offset of the SRS. The number of consecutive orthogonal frequency division multiplexing (OFDM) symbols in time-domain that are occupied by SRS can be denoted by Nsymbwhich may take a value from (1,2,4,8,10,12,14) for example.

[0031] The transmission comb can be denoted by KTCwhich may be selected from the values (2,4,8). Also, the number of antenna ports used for SRS transmission may be denoted by NSRSapwhich can be selected from a given set of values too, for example (1,2,4). There can be other parameters related to SRS transmission that the BS may send to a UE.

[0032] Furthermore, the above parameters and the range of values are just examples used to describe the present invention, hence there can be some embodiments that use parameters or values different from what is described in the examples and the present invention should be construed inclusive of all such parameters and values.

[0033] The BS may send the SRS-related configuration to a UE, where the configuration may include at least one of the parameter described above. For example, SRS bandwidth, frequency domain position, time domain position, hopping parameters etc. may be received by the UE from the BS. The UE may generate an SRS sequence using a pseudo-random sequence called Zadoff-Chu sequence. For example, cell-specific sequence identifier and UE-specific sequence cyclic-shift index may be used. It may be possible that the SRS sequence is generated by a cyclic-shift of a base sequence which is obtained from a Zadoff-Chu sequence. In some examples of 5G NR, up to 12 cyclic shifts may be employed, thus generating up to 12 orthogonal sequences. The generated sequence may be modulated and precoded by the UE based on antenna configuration, and transmitted in uplink.

[0034] (Antenna switching in SRS transmission) The RRC parameters may be configured to make a UE do antenna switching for SRS transmission. In one example, the relevant RRC parameter may be SRS-ResourceSet.usage = antennaSwitching. The UE may do antenna switching in many different ways, based on the RRC parameter setting. Furthermore, the selected antenna switching may depend on the UE capability as well.

[0035] (5G NR radio frame) A radio frame according to 5G NR may be divided into ten subframes, wherein each subframe may be of length 1 millisecond (ms). Furthermore, each such subframe may consist of one or more slots, which is decided by the numerology. For example, numerology 0 may have one slot per subframe and have a subcarrier spacing of 15 kHz. Numerology 1 may have two slots per subframe and have a subcarrier spacing of 30 kHz. An exemplary list of such numerologies is shown in the table below: (Table 2)

[0036]

[0037] Consider an example of radio frame according to numerology 1. The time slots are of length 0.5 ms, and there are 20 such slots in a radio frame. For TDD configuration, the slots may be designated as downlink (D), uplink (U), and flexible (F) slots. An exemplary TDD configuration for a group of ten slots may be expressed as DDDFUUDDDD. Furthermore, each slot may consist of 14 time-domain OFDM symbols.

[0038] 1.2) Technical problems and solution As described before, performing channel sounding by employing BSRS= 0 may require high transmit power as SRS has to be transmitted across the whole band in a single OFDM symbol, and in particular, may be difficult for UEs that are located far away from the BS. Cell-center UEs that may be capable of performing full-band sounding in a single slot (i.e., using BSRS= 0) may not be able to perform interference randomization employing frequency-hopping.

[0039] The technical problems as discussed above can be solved by performing full-band channel sounding in a single slot using different frequency sub-bands allocated to different symbols in the same time-slot, for example, by means of frequency-hopping over multiple OFDM symbols in a single time-slot. More specifically, a sub-band can be sounded in each OFDM symbol of a flexible slot or an uplink slot so that the sounding of full-band can be completed in multiple OFDM symbols but within a single flexible slot or an uplink slot. This technique can perform full-band channel sounding in a single slot, similar to BSRS= 0. However, since frequency hopping is employed, so it can employ interference randomization based on frequency hopping which is otherwise impossible in background art of BSRS= 0. Furthermore, since SRS is transmitted in only a sub-band in each OFDM symbol, hence less transmit power is required resulting in power-saving. This also means that the proposed technique can be used by the cell-edge UEs as well as the cell-center UEs by exploiting the above-mentioned benefits in terms of power spectral density (PSD).

[0040] Hereafter, an SRS-based channel sounding method according to example embodiments of the present invention will be described by referring to Figs. 1-22. The word “example” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment described herein as “example embodiment” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0041] 2. System configuration As illustrated in Figs. 1 and 2, a wireless communication system includes a plurality of communication devices where a specific communication device such as a base station (BS) or an access point may communicate with other communication devices. For simplicity, it is assumed that a BS device 100 is capable of communicating with a plurality of UE terminals 200 including two UE terminals UE1 and UE2. The UE terminals UE1 and UE2 are located within a radio coverage area (cell) 100A formed by the BS 100, allowing each UE terminal to perform uplink (UL) transmission (see Fig. 1) and the BS device 100 to perform downlink (DL) transmission with beamforming (see Fig. 2).

[0042] Fig. 3 illustrates a BS according to an example embodiment of the present invention. The BS device 100 includes a transceiver 101, a controller 102, and a program memory 103 among other modules that are not shown in the figure but can be understood by someone of ordinary skill in the art. The controller 102 may include at least one processor or central processing unit (CPU). The program memory 103 stores computer programs to be executed by the controller 102. The computer programs includes a program comprising a set of instructions for the controller 102 to perform full-band channel sounding in a single slot using randomized resource allocation over multiple OFDM symbols in a single time-slot according to the present example embodiment.

[0043] 3. Example embodiments 3.1) SRS resource allocation As illustrated in Fig. 4, the controller 102 is configured to select and assign SRS resources from a plurality of SRS resources 401 (here, n SRS resources). More specifically, the controller 102 may configure one or more SRS resources per UE per slot according to the present example embodiment of the present invention. Example of an SRS resource will be further described based on Fig. 18 and Fig. 19.

[0044] Fig. 5 and 6 show an example of SRS configuration message for periodic SRS (trigger type 0) and aperiodic SRS (trigger type 1) respectively, in LTE (Long Term Evolution). Specifically, the SRS is setup by configuring the parameters srs-Bandwidth, srs-HoppingBandwidth, freqDomainPosition, duration, srs-ConfigIndex, transmissionComb, cyclicShift and so on. Although the example shows the list of parameters for LTE, similar or new parameters can be equivalently considered for other communication systems like 5G NR. Fig. 7 shows an example of RRC message for configuring periodic SRS where the SRS-related parameters 701-704 are highlighted in boldface.

[0045] 3.2) Bandwidth configuration for SRS For comparison purposes, Fig. 8 illustrates the bandwidth configurations for SRS in background art. For example, a 100 MHz bandwidth divided into 272 RBs is considered. Four different bandwidth configurations, namely BSRS= 0, 1, 2, 3 are described. More specifically, BSRS= 0 can perform full-band channel sounding in a single slot (more specifically, in a single OFDM symbol), using a single SRS resource and without employing any frequency-hopping procedure. BSRS= 1 can perform full-band channel sounding in two slots, using a single SRS resource and employing a frequency-hopping procedure over two sub-bands (each sub-band consisting of 136 RBs). By selecting BSRS= 2, half-band channel sounding may be performed in two slots, using a single SRS resource employing a frequency-hopping procedure over two sub-bands (each sub-band consisting of 68 RBs). Hence, full-band sounding using BSRS= 2 may require two SRS resources. Furthermore, when BSRS= 3 configuration is employed, 4 RBs are sounded in each sub-band, and 17 such sub-bands may be sounded using a single SRS resource. Full-band sounding using BSRS= 3 can take 4 SRS resources and many frequency-hops, thus requiring many time-slots to estimate the whole channel.

[0046] In Fig. 9, an example of 5G NR radio frame according to an example embodiment of the present invention is shown. More specifically, numerology 1 (i.e., two slots per subframe, and 30 kHz subcarrier spacing) is considered in this example. The radio frame is of 10 ms duration, which is split into 20 slots (equivalently, 10 subframes). A time division duplexing (TDD) configuration of DDDFUUDDDD is employed, wherein D denotes downlink slot, U denotes uplink slot, and F denotes a flexible slot. Thus, out of 20 slots in the radio frame shown in FIG 9, only 2 slots are designated as F slots. Hence the F slot appears after every 10 slots. According to an example embodiment of the present disclosure, SRS may be sent in the F slots. Furthermore, each slot may consist of 14 OFDM symbols, indexed from 0 to 13. Specifically, the 14 OFDM symbols of an F slot are shown. A certain number of OFDM symbols in the F slot may be used for SRS transmission. For example, the last 6 OFDM symbols (indexed 8, 9, 10, 11, 12, 13) are shown as allocated for SRS transmission in FIG. 9. However, in some other embodiments, the number of OFDM symbols for SRS transmission in a slot may be chosen from the range 1 to 14 (i.e., from symbol index 0 to 13). Furthermore, there can be other embodiments of the present invention where the U slots may also be used for SRS transmission.

[0047] 3.3) SRS allocation with transmission comb Referring to Fig. 10 and Fig. 11, examples of an RB over one time slot are described, assuming that an RB is defined as 12 subcarriers indexed from 0 to 11, as shown along the vertical axis of the grid and a time slot consists of 14 OFDM symbols indexed from 0 to 13, as shown along the horizontal axis of the grid.

[0048] In Fig. 10, an example of SRS allocation with transmission comb KTC=2 is shown on the last OFDM symbol (symbol index = 13). More specifically, the SRS of two UEs are multiplexed in frequency domain, by allocating the alternate subcarriers on the 13-th OFDM symbol to a 1st UE and 2nd UE respectively. This is shown by using two different shades in Fig. 10, one for each UE. In a similar fashion, the SRS for more number of UEs can be multiplexed in a single OFDM symbol by using different values of transmission comb. For example, by using transmission comb KTC=4 configuration, SRS of four UEs may be multiplexed in a single OFDM symbol. This is described in Fig. 11 by using four different shades on the 13-th OFDM symbol, indicating the SRS of four different UEs on different subcarriers.

[0049] 3.4) Full-band sounding in a single slot As illustrated in Fig. 12, an example embodiment of the present invention is described by using two SRS resources and BSRS= 1 configuration. Four different UEs, namely A, B, C, and D are considered for example. The 272 RBs of the full bandwidth are divided into two sub-bands, each consisting of 136 RBs. For ease of exposition, let us name them as sub-band 1 and sub-band 2, respectively as shown in Fig. 12. For UE A, SRS allocation is done on the sub-band 1 of OFDM symbol index 10 using a first SRS resource, and on the sub-band 2 of OFDM symbol index 11 using a second SRS resource. Thus, UE A completes full-band sounding by frequency-hopping using two OFDM symbols of the same time-slot. This implies that UE A can achieve the same advantages of full-band sounding in a single slot as possible in background art by using BSRS= 0. But since UE A employs frequency-hopping, so it is capable of interference randomization based on frequency-hopping. Furthermore, since UE A transmits SRS on only a sub-band in each hop, hence it can save transmit power (in other words, improve the PSD) required for SRS transmission as compared to BSRS= 0.

[0050] It may be noted that in some embodiments, the SRS transmissions from UE A in sub-band 1 and sub-band 2 may be from the same antenna, i.e., without antenna switching at the UE within the same slot. However, transmitting SRS from one antenna in sub-band 1 and another antenna in sub-band 2 may also be considered within the scope of the present invention. For example, if the sub-bands are positioned on OFDM symbols that are separated enough to allow the required time between the two sub-bands to support antenna switching at the UE, then antenna switching (i.e., transmitting SRS from one antenna on sub-band 1 and from another antenna in sub-band 2) may be possible in some embodiments. This will be described later with an example in Fig. 23.

[0051] In a similar manner, for UE B, SRS allocation is done on the sub-band 1 of OFDM symbol index 11 using a first SRS resource, and on the sub-band 2 of OFDM symbol index 12 using a second SRS resource. Similarly for UE C, SRS allocation is done on the sub-band 1 of OFDM symbol index 12 using a first SRS resource, and on the sub-band 2 of OFDM symbol index 13 using a second SRS resource. Also, for UE D, SRS allocation is done on the sub-band 1 of OFDM symbol index 13 using a first SRS resource, and on the sub-band 2 of OFDM symbol index 10 using a second SRS resource.

[0052] Note that there can be other arrangements of frequency-hopping for the UEs A, B, C, and D, and the present invention should be construed inclusive of all such arrangements. For example, in some embodiments, the sub-bands 1 and 2 for a given UE need not be on consecutive OFDM symbols. More specifically, there can be examples where sub-band 1 and sub-band 2 of UE A are not on consecutive OFDM symbols, although they are in the same time slot (see the example in Fig. 23).

[0053] As illustrated in Fig. 13, another example embodiment of the present invention is described by using four SRS resources and b-SRS or BSRS= 2 configuration. Four different UEs, namely A, B, C, and D are considered for example. The 272 RBs of the full bandwidth are divided into 4 sub-bands, each consisting of 68 RBs. For ease of exposition, let us name them as sub-band 1, sub-band 2, sub-band 3, and sub-band 4, respectively as shown in Fig. 13.

[0054] For UE A, SRS allocation is done on the first sub-band of OFDM symbol index 10 using a first SRS resource, on the second sub-band of OFDM symbol index 11 using a second SRS resource, on the third sub-band of OFDM symbol index 12 using a third SRS resource, and on the fourth sub-band of OFDM symbol index 13 using a fourth SRS resource.

[0055] Similarly, for UE B, SRS allocation is done on the first sub-band of OFDM symbol index 11 using a first SRS resource, on the second sub-band of OFDM symbol index 12 using a second SRS resource, on the third sub-band of OFDM symbol index 13 using a third SRS resource, and on the fourth sub-band of OFDM symbol index 10 using a fourth SRS resource.

[0056] Then, for UE C, SRS allocation is done on the first sub-band of OFDM symbol index 12 using a first SRS resource, on the second sub-band of OFDM symbol index 13 using a second SRS resource, on the third sub-band of OFDM symbol index 10 using a third SRS resource, and on the fourth sub-band of OFDM symbol index 11 using a fourth SRS resource.

[0057] Furthermore, for UE D, SRS allocation is done on the first sub-band of OFDM symbol index 13 using a first SRS resource, on the second sub-band of OFDM symbol index 10 using a second SRS resource, on the third sub-band of OFDM symbol index 11 using a third SRS resource, and on the fourth sub-band of OFDM symbol index 12 using a fourth SRS resource.

[0058] Thus, each of UEs A, B, C, and D can complete full-band sounding by frequency-hopping using four OFDM symbols of the same time-slot. This implies that the UEs can achieve the same advantages of full-band channel sounding in a single slot as possible in background art by using BSRS= 0. But since the UEs employ frequency-hopping, so they are capable of interference randomization based on frequency hopping. Furthermore, since the UEs transmit SRS on only a sub-band in each hop, hence they can save transmit power required for SRS transmission as compared to BSRS= 0.

[0059] Some example embodiments of the present invention may use BSRS= 3 configuration. More specifically, a UE may hop over multiple sub-bands across different OFDM symbols in a single time slot wherein each sub-band may consist of 4 RBs. Furthermore, although the present disclosure described the present invention using examples of BSRS= 1, 2, and 3, but any other method of bandwidth allocation using which it may be possible to hop over different parts of the bandwidth in multiple OFDM symbols within a slot are also not excluded in this invention. In principle, all such hopping patterns for channel sounding over multiple OFDM symbols within the same slot should be construed as part of the present invention.

[0060] While Fig. 12 and Fig. 13 show examples of the present invention using only four UEs A, B, C, and D, but each of A, B, C, and D can also be a UE-group instead of being just a UE. This is possible by multiplexing multiple UEs in each of A, B, C, and D by using a transmission comb as discussed earlier using Fig. 10 and Fig. 11. For example, 2 UEs may be multiplexed in UE-group A by employing transmission comb KTC= 2 configuration. Similarly, 4 UEs can be multiplexed in UE-group A by employing transmission comb KTC= 4 configuration. Similarly, it may be possible to multiplex a plurality of UEs in UE-groups B, C, and D. Furthermore, the number of UEs that are multiplexed in each UE-group A, B, C, and D may be same or different by appropriate choice of transmission comb. The present invention is not limited to any specific values of transmission comb, and is inclusive of all possible values of transmission comb.

[0061] Although Fig. 12 and Fig. 13 show examples of embodiments where SRS allocation is done on only the last 4 OFDM symbols of the slot but the present invention does not limit the number of OFDM symbols or their specific index numbers in a slot that can be used for SRS. Hence, another example embodiment of the present invention may use more or less number of OFDM symbols, at different positions in the slot. For example, last 6 OFDM symbols of a F (flexible slot) or U (uplink) slot may be used for SRS transmission in some embodiments. Additionally, it may be noted that although the example in Fig. 12 employs two SRS resources per slot for each UE, it may be possible to implement it using fewer or more SRS resources in some other embodiments. Similarly, although the example shown in Fig. 13 shows an embodiment using 4 SRS resources per UE per slot, it may be possible to implement with fewer or more SRS resources. Furthermore, while the above embodiments are described for 272 RBs, it may be adapted suitably for any number of RBs to meet a system requirement.

[0062] Referring to Fig. 14 and Fig. 15, a comparison of existing channel sounding using BSRS= 0 (Fig. 14) and proposed channel sounding based on the present example embodiment (Fig. 15) is described. For both the cases, two radio frames (indexed as radio frame 0 and radio frame 1) are shown, wherein each frame consists of 20 slots. Out of the 20 slots in a radio frame, there are only two F slots in this specific example and TDD configuration. SRS is transmitted only on the F slot, and hence only the F slots are shown in finer detail with all 14 OFDM symbols indexed from 0 to 13. The full bandwidth is divided into 4 sub-bands for ease of depiction.

[0063] The existing full-band sounding is shown in Fig. 14, where the last OFDM symbol of the F-slot is used for transmitting SRS on all four sub-bands. Thus, it requires high transmit power to transmit SRS across the entire bandwidth in a single OFDM symbol.

[0064] In contrast, an example of the proposed channel sounding according to the present example embodiment is shown in Fig. 15, where SRS is transmitted on each sub-band in a different OFDM symbol. Thus, transmit power required for SRS transmission is reduced. Furthermore, hopping over the sub-bands can allow flexibility for interference randomization.

[0065] According to an example embodiment of the present invention, a sub-band may be formed of one or more subcarriers. In an example embodiment of the present invention, it may be possible that two or more sub-bands allocated to different symbols in the same time-slot may include at least one common subcarrier. For example, consider that a first sub-band is allocated to a first OFDM symbol, and a second sub-band is allocated to a second OFDM symbol, wherein both the first OFDM symbol and the second OFDM symbol are in the same time-slot. It may be possible in an example that one or more subcarriers contained in the first sub-band are also contained in the second sub-band. By estimating a same subcarrier in more than one symbol, the quality and reliability of channel estimation or channel sounding can be improved.

[0066] 3.5) Interference randomization Orthogonal SRS sequences may be used for UEs to avoid interference. However, to serve a large number of UEs, it may be necessary to reuse SRS sequences. Such reuse of SRS among neighboring transmission and reception points (TRPs) can cause interference among SRS transmissions, thus resulting in possible channel estimation error. In Release-18 of the 3GPP specifications, reference signal enhancements are aimed for. Specifically, it has been agreed that SRS enhancements to manage inter-TRP cross-SRS interference will be considered. Towards that, randomized frequency-domain resource mapping for SRS transmission by utilizing frequency-hopping, comb hopping and cyclic-shift hopping can be deemed useful.

[0067] With reference to Fig. 16, a set of exemplary steps of operations at the BS is described, where an example embodiment of the present invention is applied. In one step 1501, a BS configures the SRS transmission parameters for a UE such that one or more SRS resources are allocated to a UE per slot enabling the UE to transmit SRS on at least two sub-bands on at least two different OFDM symbols in the same slot. In the following step 1502, the BS sends the SRS configuration to the UE.

[0068] With reference to Fig. 17, a set of exemplary steps of operations at the UE is described, where an example embodiment of the present invention is applied. In one step 1601, a UE receives the SRS configuration from a BS. In the following step 1602, the UE transmits SRS according to the received SRS configuration wherein SRS is transmitted on at least two sub-bands on at least two different OFDM symbols in the same time slot.

[0069] With reference to Fig. 18, an example of SRS Resource configuration 401 is shown in NPL 3 (page 889). Such a configuration may contain the values of various SRS parameters including but not limited to srs-ResourceID, nrofSRS-Ports, ptrs-PortIndex, transmissionComb, startPosition, nrofsymbols, repetitionFactor, freqDomainPosition, freqDomainShift, freqHopping, c-SRS, b-SRS, b-hop, SRS-PeriodicityAndOffset etc. Each of these parameters may define certain properties of the allocated SRS. Particularly, in semi-persistent SEQUENCE, periodicityAndOffset-sp is shown. Furthermore, in periodic SEQUENCE, periodicityAndOffset is shown.

[0070] With reference to Fig. 19, a further detail of SRS configuration is explained by referring to NPL 3 (pages 891-893). More specifically, SRS-SpatialRelationInfo and SRS-PeriodicityAndOffset are shown in Fig. 19. For example, by choosing “sl160” in Fig. 19, it may be possible to configure an SRS periodicity of 160 slots, i.e., an SRS is sent after interval of every 160 slots. Furthermore, choosing an integer from (0,…,159) corresponding to sl160 may define the offset. In one example, two SRS resources having the same parameters sl160 and offset=1 (just example) may be configured on the same time slot and may have the same periodicity. Similarly, the parameters related to start position and offset in frequency domain can also be chosen appropriately to define the frequency-domain positioning of SRS.

[0071] An SRS-Config Information Element (IE) is shown in Figs. 20A-20I, according to NPL 3. Note that Figs. 20A-20I partly shows the SRS-Config Information described in pages 887-894 of NPL 3 for simplicity but all contents of the SRS-Config information should be included in Figs. 20A-20I. As illustrated in Figs. 20A and 20B, reference signs 2001-A and 2001-B show an abstract syntax notation (ASN) for SRS-ResourceSet. Furthermore, as illustrated in Figs. 20C-20F, reference signs 2002-A and 2002-B indicate the ASN for SRS-Resource. Also, as illustrated in Figs. 20G-20I, reference signs 2003-A and 2003-B indicate the ASN for SRS-PeriodicityAndOffset. It will be understood that some of the parameters shown in the SRS-Config IE will be grouped in the common parameters, while some other parameters shown in the SRS-Config IE will be grouped in the specific parameters according an example embodiment of the present invention. This disclosure only describes using some example parameters, however any other combination of one or more parameters shown in Figs. 20A-20I can be used in the present invention.

[0072] 4. New RRC signaling In the example embodiment of the present invention described earlier in accordance with Fig. 12, two SRS resources per UE per time slot was discussed. However, in another example embodiment of the present invention, it may be possible to configure the SRS for a UE on two sub-bands using two OFDM symbols of the same slot using a single SRS resource.

[0073] In a similar fashion, according to Fig. 13, four SRS resources per UE per time slot was discussed. However, in further another example embodiment of the present invention, it may be possible to configure the SRS for a UE on four sub-bands using four OFDM symbols of the same time slot using a single SRS resource. Such embodiments may have the advantage of requiring fewer SRS resources than background art of SRS configuration used in RRC signaling.

[0074] In one example embodiment, it may be possible that a plurality of SRS resources that are allocated to a UE can be combined together in a single integrated SRS resource, or in a single combined SRS configuration message in RRC signaling. This can reduce the overhead of RRC signaling message size.

[0075] With reference to Fig. 21, a technique for SRS configuration is described according to one example embodiment of the present invention. For example, in some embodiments, multiple SRS resources may have to be allocated per UE per time slot to enable frequency hopping in different parts of the bandwidth using multiple OFDM symbols within the same time slot. However, allocating multiple SRS resources per UE may increase the message size in RRC signaling. To avoid such overhead, another embodiment of the proposed RRC signaling is described with reference to Fig. 21, Figs. 22A and22B. Basically, a plurality of SRS resources that are allocated to a UE can be combined together in a single SRS configuration or a single SRS resource.

[0076] As shown in Fig. 21, the set of all parameters 1901 related to SRS configuration are divided into two categories, wherein a first category 1902 is named as common parameters, and a second category 1903 is named as specific parameters. Instead of defining all configuration parameters corresponding to each SRS Resource allocated to a UE, it may be possible to define a combined configuration wherein the parameters that have same values (we call them as common parameters) are defined only once since they have same values for the plurality of SRS resources. Furthermore, the specific parameters (i.e., the parameters that have different values in each SRS Resource) corresponding to each of the plurality of SRS Resources allocated to a UE are all defined in the combined configuration one after another since the specific parameters have different values for each one of the plurality of SRS resources.

[0077] An example of this technique is further shown in Figs. 22A and 22B. In this example, it is assumed that a UE is configured four SRS Resources. In background art, this may necessitate to define all the SRS configuration parameters (shown earlier in Fig. 18) for each of the 4 SRS Resources, resulting in increased message overhead in RRC signaling. However, since all of the 4 SRS Resources are assigned to the same UE in the same time slot, they have many common parameters. Thus, the parameters including but not limited to time slot index, CSRS, BSRS,transmission comb, cyclic-shift, and periodicity related parameters may be same.

[0078] The example shown in Figs. 22A and 22B enlists many other common parameters like number of SRS ports (nrofSRS-Ports), number of symbols (nrofSymbols), repetition factor (repetitionFactor), frequency-hopping parameter (b-hop) etc. But the 4 SRS Resources may have different OFDM symbol index and different frequency position. Hence, only such specific parameters that have different values in each SRS Resource assigned to the same UE may be defined separately for each SRS Resource.

[0079] In the example shown in Figs. 22A and 22B, after the definition of the common parameters, an exemplary list of specific parameters are shown (startPosition and freqDomainPosition) for each of the 4 SRS Resources. For example, a startPosition may indicate an OFDM symbol index which may be different for each SRS Resource allocated to the same UE in a single time-slot.

[0080] In the example of Figs. 22A and 22B, the parameter startPosition can have values from (0, 1, 2, 3, 4, 5). Furthermore, a freqDomainPosition may indicate the position of SRS Resource in the frequency domain in terms of resource block (RB).

[0081] In the example of Figs. 22A and 22B, the parameter freqDomainPosition can have values from (0, 1, …, 63). Thus, in the example of Figs. 22A and 22B, the parameters startPosition and freqDomainPosition may have different values for each SRS Resource, and defined individually after the common parameters. Such a technique to combine multiple SRS Resources into a single configuration can reduce the overhead of RRC signaling message in an example embodiment of the present invention. In other words, the present example embodiment of the invention can be used as new RRC signaling technique where multiple SRS resources allocated to a UE are combined together to form a single SRS configuration or SRS Resource.

[0082] 5. Antenna switching With reference to Fig. 23, another example embodiment of the present invention is described employing antenna switching. In one example for UE A, SRS allocation is done on the sub-band 1 of OFDM symbol index 10 using a first SRS resource for a first antenna (shown as A1), and on the sub-band 2 of OFDM symbol index 12 using a second SRS resource for a second antenna (shown as A2). The gap of one OFDM symbol between the SRS transmission from first antenna (A1) and SRS transmission from the second antenna (A2) may enable antenna switching. Using similar method, a gap of one OFDM symbol may be inserted between the SRS transmissions from first and second antennas of UE B. Specifically, for UE B, the SRS transmission from first antenna is shown as B1 (OFDM symbol index 11, sub-band 1) and that from the second antenna is shown as B2 (OFDM symbol index 13, sub-band 2). Similar techniques are applied for UE C and UE D as well, as shown in Fig. 23. In some other embodiments, it may be possible to adjust the gap of OFDM symbols between SRS transmission from different antennas of a UE depending on the system requirements and UE capability.

[0083] 6.　Supplementary remarks Application software in accordance with the present disclosure, such as computer programs executed by the device and may be stored on one or more computer readable mediums. It is also contemplated that the steps identified herein may be implemented using one or more general purpose or specific purpose computers and / or computer systems, networked and / or otherwise. Where applicable, the ordering of various steps described herein may be changed, combined into composite steps, and / or separated into sub-steps to provide features described herein.

[0084] The User Equipment (or “UE”, “mobile station”, “mobile device” or “wireless device”) in the present disclosure is an entity connected to a network via a wireless interface.

[0085] It should be noted that the present disclosure is not limited to a dedicated communication device, and can be applied to any device having a communication function as explained in the following paragraphs.

[0086] The terms “User Equipment” or “UE” (as the term is used by 3GPP), “mobile station”, “mobile device”, and “wireless device” are generally intended to be synonymous with one another, and include standalone mobile stations, such as terminals, cell phones, smart phones, tablets, cellular IoT devices, IoT devices, and machinery. It will be appreciated that the terms “mobile station” and “mobile device” also encompass devices that remain stationary for a long period of time.

[0087] A UE may, for example, be an item of equipment for production or manufacture and / or an item of energy related machinery (for example equipment or machinery such as: boilers; engines; turbines; solar panels; wind turbines; hydroelectric generators; thermal power generators; nuclear electricity generators; batteries; nuclear systems and / or associated equipment; heavy electrical machinery; pumps including vacuum pumps; compressors; fans; blowers; oil hydraulic equipment; pneumatic equipment; metal working machinery; manipulators; robots and / or their application systems; tools; molds or dies; rolls; conveying equipment; elevating equipment; materials handling equipment; textile machinery; sewing machines; printing and / or related machinery; paper converting machinery; chemical machinery; mining and / or construction machinery and / or related equipment; machinery and / or implements for agriculture, forestry and / or fisheries; safety and / or environment preservation equipment; tractors; precision bearings; chains; gears; power transmission equipment; lubricating equipment; valves; pipe fittings; and / or application systems for any of the previously mentioned equipment or machinery etc.).

[0088] A UE may, for example, be an item of transport equipment (for example transport equipment such as: rolling stocks; motor vehicles; motor cycles; bicycles; trains; buses; carts; rickshaws; ships and other watercraft; aircraft; rockets; satellites; drones; balloons etc.).

[0089] A UE may, for example, be an item of information and communication equipment (for example information and communication equipment such as: electronic computer and related equipment; communication and related equipment; electronic components etc.).

[0090] A UE may, for example, be a refrigerating machine, a refrigerating machine applied product, an item of trade and / or service industry equipment, a vending machine, an automatic service machine, an office machine or equipment, a consumer electronic and electronic appliance (for example a consumer electronic appliance such as: audio equipment; video equipment; a loud speaker; a radio; a television; a microwave oven; a rice cooker; a coffee machine; a dishwasher; a washing machine; a dryer; an electronic fan or related appliance; a cleaner etc.).

[0091] A UE may, for example, be an electrical application system or equipment (for example an electrical application system or equipment such as: an x-ray system; a particle accelerator; radio isotope equipment; sonic equipment; electromagnetic application equipment; electronic power application equipment etc.).

[0092] A UE may, for example, be an electronic lamp, a luminaire, a measuring instrument, an analyzer, a tester, or a surveying or sensing instrument (for example a surveying or sensing instrument such as: a smoke alarm; a human alarm sensor; a motion sensor; a wireless tag etc.), a watch or clock, a laboratory instrument, optical apparatus, medical equipment and / or system, a weapon, an item of cutlery, a hand tool, or the like.

[0093] A UE may, for example, be a wireless-equipped personal digital assistant or related equipment (such as a wireless card or module designed for attachment to or for insertion into another electronic device (for example a personal computer, electrical measuring machine)).

[0094] A UE may be a device or a part of a system that provides applications, services, and solutions described below, as to “internet of things (IoT)”, using a variety of wired and / or wireless communication technologies.

[0095] Internet of Things devices (or “things”) may be equipped with appropriate electronics, software, sensors, network connectivity, and / or the like, which enable these devices to collect and exchange data with each other and with other communication devices. IoT devices may comprise automated equipment that follow software instructions stored in an internal memory. IoT devices may operate without requiring human supervision or interaction. IoT devices might also remain stationary and / or inactive for a long period of time. IoT devices may be implemented as a part of a (generally) stationary apparatus. IoT devices may also be embedded in non-stationary apparatus (e.g. vehicles) or attached to animals or persons to be monitored / tracked.

[0096] It will be appreciated that IoT technology can be implemented on any communication devices that can connect to a communications network for sending / receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory.

[0097] It will be appreciated that IoT devices are sometimes also referred to as Machine-Type Communication (MTC) devices or Machine-to-Machine (M2M) communication devices. It will be appreciated that a UE may support one or more IoT or MTC applications. Some examples of MTC applications are listed in the following table (source: 3GPP TS 22.368 V13.1.0, Annex B, the contents of which are incorporated herein by reference). This list is not exhaustive and is intended to be indicative of some examples of machine-type communication applications. (Table 3)

[0098]

[0099] Applications, services, and solutions may be an MVNO (Mobile Virtual Network Operator) service, an emergency radio communication system, a PBX (Private Branch eXchange) system, a PHS / Digital Cordless Telecommunications system, a POS (Point of sale) system, an advertise calling system, an MBMS (Multimedia Broadcast and Multicast Service), a V2X (Vehicle to Everything) system, a train radio system, a location related service, a Disaster / Emergency Wireless Communication Service, a community service, a video streaming service, a femto cell application service, a VoLTE (Voice over LTE) service, a charging service, a radio on demand service, a roaming service, an activity monitoring service, a telecom carrier / communication NW selection service, a functional restriction service, a PoC (Proof of Concept) service, a personal information management service, an ad-hoc network / DTN (Delay Tolerant Networking) service, etc.

[0100] Further, the above-described UE categories are merely examples of applications of the technical ideas and example embodiments described in the present document. Needless to say, these technical ideas and embodiments are not limited to the above-described UE and various modifications can be made thereto.

[0101] It should also be understood that embodiments of the present disclosure should not be limited to these embodiments but that numerous modifications and variations may be made by one of ordinary skill in the art in accordance with the principles of the present disclosure and be included within the spirit and scope of the present disclosure as hereinafter claimed.

[0102] 7. Supplementary Notes The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes.

[0103] (Supplementary Note 1) A communication device comprising: a wireless transceiver configured to communicate with another communication device through a wireless channel; and at least one controller configured to send at least one information to the another communication device, such that the another communication device transmits uplink reference signal to the communication device following the at least one information, using two or more symbols in a time-slot with at least one non-overlapping subcarrier. (Supplementary Note 2) The communication device according to supplementary note1 wherein the uplink reference signal is a sounding reference signal (SRS). (Supplementary Note 3) The communication device according to supplementary note 1 or 2 wherein the uplink reference signal is at least one of a periodic SRS, a semi-persistent SRS, or an aperiodic SRS. (Supplementary Note 4) The communication device according to any one of supplementary notes 1-3 wherein the at least one information includes at least one of an SRS resource comprising: a. bandwidth configuration for SRS transmission b. periodicity for SRS transmission (Supplementary Note 5) The communication device according to any one of supplementary notes 1-3, wherein the SRS is transmitted using a bandwidth configuration which is at least one of b-SRS = 1, 2, or 3. (Supplementary Note 6) The communication device according to any one of supplementary notes 1-3, and 5, wherein the SRS is transmitted on at least one first sub-band and at least one second sub-band such that: a. the first sub-band includes at least one subcarrier that is not included in the second sub-band. b. the first sub-band and second sub-band are configured in the same time slot, but on different symbols. (Supplementary Note 7) The communication device according to supplementary note 6 wherein the SRS configuration is done using a single SRS resource. (Supplementary Note 8) The communication device according to any one of supplementary notes 1 to 7, wherein a gap of at least one OFDM symbol is inserted between the first sub-band and the at least one second sub-band of a UE to enable antenna switching. (Supplementary Note 9) The communication device according to any one of supplementary notes 1 to 8 wherein a set of common parameters are configured as same for all SRS Resources of a UE, and another set of specific parameters are configured differently for each SRS Resource of a UE. (Supplementary Note 10) The communication device according to any one of supplementary notes 1 to 6 wherein the SRS configuration is done with at least one of: a. frequency-hopping b. comb hopping c. cyclic-shift hopping. (Supplementary Note 11) A communication device comprising: a wireless transceiver configured to communicate with another communication device through a wireless channel and at least one controller configured to send at least one information to the another communication device, such that the another communication device transmits uplink sounding reference signal (SRS) to the communication device following the at least one information, using two or more symbols in a single time-slot with at least one non-overlapping subcarrier wherein: a) a plurality of SRS resources are integrated into a single combined SRS resource and allocated to the another communication device b) the parameters having common values in the plurality of SRS resources according to the a) are specified only once in the combined SRS resource, and the parameters with different values in the plurality of SRS resources are specified individually in the combined SRS resource. (Supplementary Note 12) The communication device according to supplementary note 11 wherein at least one of the parameters c-SRS, b-SRS, slot index, periodicity has common values for the plurality of SRS resources. (Supplementary Note 13) The communication device according to supplementary note 11 wherein at least one of the startPosition and freqDomainPosition has different values for the plurality of SRS resources. (Supplementary Note 14) A communication method comprising: a wireless transceiver configured to communicate with another communication device through a wireless channel and at least one controller configured to send at least one information to the another communication device, such that the another communication device transmits uplink sounding reference signal (SRS) to the communication device following the at least one information, using two or more symbols in a single time-slot with at least one non-overlapping subcarrier wherein: a) a plurality of SRS resources are integrated into a single combined SRS resource and allocated to the another communication device b) the parameters having common values in the plurality of SRS resources according to the a) are specified only once in the combined SRS resource, and the parameters with different values in the plurality of SRS resources are specified individually in the combined SRS resource. (Supplementary Note 15) The communication method according to supplementary note 14 wherein at least one of the parameters c-SRS, b-SRS slot index, periodicity has common values for the plurality of SRS resources. (Supplementary Note 16) The communication method according to supplementary note 14 wherein at least one of the startPosition and freqDomainPosition has different values for the plurality of SRS resources. (Supplementary Note 17) A method for radio resource control (RRC) signaling to configure sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration and allocated by a base station to a user terminal. (Supplementary Note 18) A method for radio resource control (RRC) signaling according to supplementary note 17 wherein the user terminal can use multiple SRS resources in a single time slot. (Supplementary Note 19) A method according to supplementary note 17 or 18 wherein parameters related to SRS configuration in the multiple SRS resources are separated into common parameters and specific parameters. (Supplementary Note 20) A method according to any one of supplementary notes 17 to 19 wherein: (a) the common parameters have same values in the multiple SRS resources and are specified only once in the combined configuration, and (b) the specific parameters have different values in the multiple SRS resources and all different values are specified individually in the combined configuration.

[0104] 8. Further Supplementary Notes The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following further supplementary notes.

[0105] (Further supplementary note 1) A communication device comprising: a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid; and at least one processor configured to: generate configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and send the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver. (Further supplementary note 2) The communication device according to further supplementary note 1, wherein the reference signal is a sounding reference signal (SRS). (Further supplementary note 3) The communication device according to further supplementary note 2 wherein the reference signal is at least one of a periodic SRS, a semi-persistent SRS, or an aperiodic SRS. (Further supplementary note 4) The communication device according to any one of further supplementary notes 1-3, wherein the configuration information enables the another communication device to perform frequency hopping over different Orthogonal Frequency Division Multiplexing (OFDM) symbols in the single time slot. (Further supplementary note 5) The communication device according to further supplementary note 4, wherein the at least one processor performs full-band channel sounding in the single time-slot according to randomized resource allocation over the different OFDM symbols in the single time-slot. (Further supplementary note 6) The communication device according to any one of further supplementary notes 1-5, wherein the configuration information configures at least one of reference signal resources of: a) bandwidth configuration for the reference signal transmission; and b) periodicity for the reference signal transmission. (Further supplementary note 7) The communication device according to any one of further supplementary notes 1-6, wherein the configuration information configures a bandwidth configuration which is at least one of BSRS= 1, 2, or 3 according to Third Generation Partnership Project Technical Specification 3GPP TS 38.211. (Further supplementary note 8) The communication device according to any one of further supplementary notes 1-7, wherein the configuration information configures at least one first sub-band and at least one second sub-band, wherein: the first sub-band includes at least one subcarrier that is not included in the second sub-band; and the first sub-band and the second sub-band are configured in same time-slot but on different symbols. (Further supplementary note 9) The communication device according to further supplementary note 8, wherein the configuration for the reference signal transmission is done using a single SRS resource. (Further supplementary note 10) The communication device according to any one of further supplementary notes 1-9, wherein a gap of at least one symbol is inserted between reference signal transmissions respectively from different antennas of the another communication device to enable antenna switching. (Further supplementary note 11) The communication device according to any one of further supplementary notes 1-10, wherein the configuration information enables the reference signal transmission through at least one of frequency-hopping, comb hopping, and cyclic-shift hopping. (Further supplementary note 12) The communication device according to any one of further supplementary notes 1-11, wherein a plurality of reference signal resources are integrated into a single combined reference signal resource and allocated to the another communication device, wherein a set of parameters related to the configuration information includes a first set of common parameters and a second set of specific parameters, wherein the first set of common parameters are configured as same for the reference signal resources, and the second set of specific parameters are configured differently for each of the reference signal resources. (Further supplementary note 13) The communication device according to further supplementary note 12, wherein the first set of common parameters include at least one of parameters of c-SRS, b-SRS, slotIndex, periodicityAndOffset-p, and periodicityAndOffset-sp according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having common values for the plurality of reference signal resources. (Further supplementary note 14) The communication device according to further supplementary note 12 or 13, wherein the second set of specific parameters include at least one of the startPosition and freqDomainPosition according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having different values for the plurality of reference signal resources. (Further supplementary note 15) The communication device according to any one of further supplementary notes 1-14, wherein the different frequency sub-bands include a first frequency sub-band and a second frequency sub-band, wherein the first frequency sub-band is allocated to a first symbol, the second frequency sub-band is allocated to a second symbol, and the first symbol and the second symbol are in the single time-slot according to the configuration information. (Further supplementary note 16) A communication method of a communication device including a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid; and a controller, the communication method by the controller, comprising: generating configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and sending the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver. (Further supplementary note 17) The communication method according to further supplementary note 16, wherein the reference signal is a sounding reference signal (SRS). (Further supplementary note 18) The communication method according to further supplementary note 17, wherein the reference signal is at least one of a periodic SRS, a semi-persistent SRS, or an aperiodic SRS. (Further supplementary note 19) The communication method according to any one of further supplementary notes 16-18, wherein the configuration information enables the another communication device to perform frequency hopping over different Orthogonal Frequency Division Multiplexing (OFDM) symbols in the single time slot. (Further supplementary note 20) The communication method according to further supplementary note 19, wherein full-band channel sounding in the single time-slot is performed according to randomized resource allocation over the different OFDM symbols in the single time-slot. (Further supplementary note 21) The communication method according to any one of further supplementary notes 16-20, wherein the configuration information configures at least one of reference signal resources of: a) bandwidth configuration for the reference signal transmission; and b) periodicity for the reference signal transmission. (Further supplementary note 22) The communication method according to any one of further supplementary notes 16-21, wherein the configuration information configures a bandwidth configuration which is at least one of BSRS= 1, 2, or 3 according to Third Generation Partnership Project Technical Specification 3GPP TS 38.211. (Further supplementary note 23) The communication method according to any one of further supplementary notes 16-22, wherein the configuration information configures at least one first sub-band and at least one second sub-band, wherein: the first sub-band includes at least one subcarrier that is not included in the second sub-band; and the first sub-band and the second sub-band are configured in same time-slot but on different symbols. (Further supplementary note 24) The communication method according to further supplementary note 23, wherein the configuration for the reference signal transmission is done using a single SRS resource. (Further supplementary note 25) The communication method according to any one of further supplementary notes 16-24, wherein a gap of at least one symbol is inserted between reference signal transmissions respectively from different antennas of the another communication device to enable antenna switching. (Further supplementary note 26) The communication method according to any one of further supplementary notes 16-25, wherein the configuration information enables the reference signal transmission through at least one of frequency-hopping, comb hopping, and cyclic-shift hopping. (Further supplementary note 27) The communication method according to any one of further supplementary notes 16-26, wherein a plurality of reference signal resources are integrated into a single combined reference signal resource and allocated to the another communication device, wherein a set of parameters related to the configuration information includes a first set of common parameters and a second set of specific parameters, wherein the first set of common parameters are configured as same for the reference signal resources, and the second set of specific parameters are configured differently for each of the reference signal resources. (Further supplementary note 28) The communication method according to further supplementary note 27, wherein the first set of common parameters include at least one of parameters of c-SRS, b-SRS, slotIndex, periodicityAndOffset-p, and periodicityAndOffset-sp according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having common values for the plurality of reference signal resources. (Further supplementary note 29) The communication method according to further supplementary note 27 or 28, wherein the second set of specific parameters include at least one of the startPosition and freqDomainPosition according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having different values for the plurality of reference signal resources. (Further supplementary note 30) The communication method according to any one of further supplementary notes 16-29, wherein the different frequency sub-bands include a first frequency sub-band and a second frequency sub-band, wherein the first frequency sub-band is allocated to a first symbol, the second frequency sub-band is allocated to a second symbol, and the first symbol and the second symbol are in the single time-slot according to the configuration information. (Further supplementary note 31) A communication method for radio resource control (RRC) signaling in a communication system including a base station and a user terminal, the method by the base station comprising: configuring a sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration; and allocating the single combined configuration to the user terminal. (Further supplementary note 32) The communication method according to further supplementary note 31, wherein the user terminal is configured to use the multiple SRS resources in a single time slot to send the SRS to the base station. (Further supplementary note 33) The communication method according to further supplementary note 31 or 32, wherein parameters related to the single combined configuration are separated into common parameters and specific parameters, wherein the common parameters are configured as same for the multiple SRS resources, wherein the specific parameters are configured differently for each of the multiple SRS resources. (Further supplementary note 34) The communication method according to further supplementary note 33, wherein: the common parameters have same values in the multiple SRS resources and are specified only once in the single combined configuration, and the specific parameters have different values in the multiple SRS resources and all different values are specified individually in the single combined configuration. (Further supplementary note 35) A program executed by a controller of a communication device including a wireless transceiver configured to communicate with another communication device through a wireless channel in predetermined resource grid, the program comprising a set of instructions for: generating configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and sending the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver. (Further supplementary note 36) A program executed by a controller of a base station for radio resource control (RRC) signaling, the program comprising a set of instructions for: configuring a sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration; and allocating the single combined configuration to a user terminal. (Further supplementary note 37) The program according to further supplementary note 36, wherein the user terminal is configured to use the multiple SRS resources in a single time slot to send the SRS to the base station. (Further supplementary note 38) The program according to further supplementary note 36 or 37, wherein parameters related to the single combined configuration are separated into common parameters and specific parameters, wherein the common parameters are configured as same for the multiple SRS resources, wherein the specific parameters are configured differently for each of the multiple SRS resources. (Further supplementary note 39) The program according to further supplementary note 38, wherein: the common parameters have same values in the multiple SRS resources and are specified only once in the single combined configuration, and the specific parameters have different values in the multiple SRS resources and all different values are specified individually in the single combined configuration.

[0106] The above-described example embodiments can be applied to wireless communication devices such as radio base stations and radio access point.

[0107] 100 Base station 101 Transceiver 102 Controller 103 Program memory 200 User terminal

Claims

1. A communication device comprising: a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid ; and at least one processor configured to: generate configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and send the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver.

2. The communication device according to claim 1, wherein the reference signal is a sounding reference signal (SRS).

3. The communication device according to claim 2 wherein the reference signal is at least one of a periodic SRS, a semi-persistent SRS, or an aperiodic SRS.

4. The communication device according to any one of claims 1-3, wherein the configuration information enables the another communication device to perform frequency hopping over different Orthogonal Frequency Division Multiplexing (OFDM) symbols in the single time slot.

5. The communication device according to claim 4, wherein the at least one processor performs full-band channel sounding in the single time-slot according to randomized resource allocation over the different OFDM symbols in the single time-slot.

6. The communication device according to any one of claims 1-5, wherein the configuration information configures at least one of reference signal resources of: a) bandwidth configuration for the reference signal transmission; and b) periodicity for the reference signal transmission.

7. The communication device according to any one of claims 1-6, wherein the configuration information configures a bandwidth configuration which is at least one of BSRS= 1, 2, or 3 according to Third Generation Partnership Project Technical Specification 3GPP TS 38.211.

8. The communication device according to any one of claims 1-7, wherein the configuration information configures at least one first sub-band and at least one second sub-band, wherein: the first sub-band includes at least one subcarrier that is not included in the second sub-band; and the first sub-band and the second sub-band are configured in same time-slot but on different symbols.

9. The communication device according to claim 8, wherein the configuration for the reference signal transmission is done using a single SRS resource.

10. The communication device according to any one of claims 1-9, wherein a gap of at least one symbol is inserted between reference signal transmissions respectively from different antennas of the another communication device to enable antenna switching.

11. The communication device according to any one of claims 1-10, wherein the configuration information enables the reference signal transmission through at least one of frequency-hopping, comb hopping, and cyclic-shift hopping.

12. The communication device according to any one of claims 1-11, wherein a plurality of reference signal resources are integrated into a single combined reference signal resource and allocated to the another communication device, wherein a set of parameters related to the configuration information includes a first set of common parameters and a second set of specific parameters, wherein the first set of common parameters are configured as same for the reference signal resources, and the second set of specific parameters are configured differently for each of the reference signal resources.

13. The communication device according to claim 12, wherein the first set of common parameters include at least one of parameters of c-SRS, b-SRS, slotIndex, periodicityAndOffset-p, and periodicityAndOffset-sp according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having common values for the plurality of reference signal resources.

14. The communication device according to claim 12 or 13, wherein the second set of specific parameters include at least one of the startPosition and freqDomainPosition according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having different values for the plurality of reference signal resources.

15. The communication device according to any one of claims 1-14, wherein the different frequency sub-bands include a first frequency sub-band and a second frequency sub-band, wherein the first frequency sub-band is allocated to a first symbol, the second frequency sub-band is allocated to a second symbol, and the first symbol and the second symbol are in the single time-slot according to the configuration information.

16. A communication method of a communication device including a wireless transceiver configured to communicate with another communication device through a wireless channel in a predetermined resource grid; and a controller, the communication method by the controller, comprising: generating configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and sending the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver.

17. The communication method according to claim 16, wherein the reference signal is a sounding reference signal (SRS).

18. The communication method according to claim 17, wherein the reference signal is at least one of a periodic SRS, a semi-persistent SRS, or an aperiodic SRS.

19. The communication method according to any one of claims 16-18, wherein the configuration information enables the another communication device to perform frequency hopping over different Orthogonal Frequency Division Multiplexing (OFDM) symbols in the single time slot.

20. The communication method according to claim 19, wherein full-band channel sounding in the single time-slot is performed according to randomized resource allocation over the different OFDM symbols in the single time-slot.

21. The communication method according to any one of claims 16-20, wherein the configuration information configures at least one of reference signal resources of: a) bandwidth configuration for the reference signal transmission; and b) periodicity for the reference signal transmission.

22. The communication method according to any one of claims 16-21, wherein the configuration information configures a bandwidth configuration which is at least one of BSRS= 1, 2, or 3 according to Third Generation Partnership Project Technical Specification 3GPP TS 38.211.

23. The communication method according to any one of claims 16-22, wherein the configuration information configures at least one first sub-band and at least one second sub-band, wherein: the first sub-band includes at least one subcarrier that is not included in the second sub-band; and the first sub-band and the second sub-band are configured in same time-slot but on different symbols.

24. The communication method according to claim 23, wherein the configuration for the reference signal transmission is done using a single SRS resource.

25. The communication method according to any one of claims 16-24, wherein a gap of at least one symbol is inserted between reference signal transmissions respectively from different antennas of the another communication device to enable antenna switching.

26. The communication method according to any one of claims 16-25, wherein the configuration information enables the reference signal transmission through at least one of frequency-hopping, comb hopping, and cyclic-shift hopping.

27. The communication method according to any one of claims 16-26, wherein a plurality of reference signal resources are integrated into a single combined reference signal resource and allocated to the another communication device, wherein a set of parameters related to the configuration information includes a first set of common parameters and a second set of specific parameters, wherein the first set of common parameters are configured as same for the reference signal resources, and the second set of specific parameters are configured differently for each of the reference signal resources.

28. The communication method according to claim 27, wherein the first set of common parameters include at least one of parameters of c-SRS, b-SRS, slotIndex, periodicityAndOffset-p, and periodicityAndOffset-sp according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having common values for the plurality of reference signal resources.

29. The communication method according to claim 27 or 28, wherein the second set of specific parameters include at least one of the startPosition and freqDomainPosition according to at least one of Third Generation Partnership Project Technical Specification 3GPP TS 38.211 and 3GPP TS 38.331 having different values for the plurality of reference signal resources.

30. The communication method according to any one of claims 16-29, wherein the different frequency sub-bands include a first frequency sub-band and a second frequency sub-band, wherein the first frequency sub-band is allocated to a first symbol, the second frequency sub-band is allocated to a second symbol, and the first symbol and the second symbol are in the single time-slot according to the configuration information.

31. A communication method for radio resource control (RRC) signaling in a communication system including a base station and a user terminal, the method by the base station comprising: configuring a sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration; and allocating the single combined configuration to the user terminal.

32. The communication method according to claim 31, wherein the user terminal is configured to use the multiple SRS resources in a single time slot to send the SRS to the base station.

33. The communication method according to claim 31 or 32, wherein parameters related to the single combined configuration are separated into common parameters and specific parameters, wherein the common parameters are configured as same for the multiple SRS resources, wherein the specific parameters are configured differently for each of the multiple SRS resources.

34. The communication method according to claim 33, wherein: the common parameters have same values in the multiple SRS resources and are specified only once in the single combined configuration, and the specific parameters have different values in the multiple SRS resources and all different values are specified individually in the single combined configuration.

35. A program executed by a controller of a communication device including a wireless transceiver configured to communicate with another communication device through a wireless channel in predetermined resource grid, the program comprising a set of instructions for: generating configuration information for reference signal transmission of the another communication device, wherein different frequency sub-bands are allocated to different symbols in a single time-slot according to the configuration information; and sending the configuration information to the another communication device through the wireless transceiver so that a reference signal following the configuration information is received from the another communication device through the wireless transceiver.

36. A program executed by a controller of a base station for radio resource control (RRC) signaling, the program comprising a set of instructions for: configuring a sounding reference signal (SRS) wherein multiple SRS resources are combined in a single combined configuration; and allocating the single combined configuration to a user terminal.

37. The program according to claim 36, wherein the user terminal is configured to use the multiple SRS resources in a single time slot to send the SRS to the base station.

38. The program according to claim 36 or 37, wherein parameters related to the single combined configuration are separated into common parameters and specific parameters, wherein the common parameters are configured as same for the multiple SRS resources, wherein the specific parameters are configured differently for each of the multiple SRS resources.

39. The program according to claim 38, wherein: the common parameters have same values in the multiple SRS resources and are specified only once in the single combined configuration, and the specific parameters have different values in the multiple SRS resources and all different values are specified individually in the single combined configuration.

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