WO2016029971A1

WO2016029971A1 - Carrier modulation in communications

Info

Publication number: WO2016029971A1
Application number: PCT/EP2014/068431
Authority: WO
Inventors: Esa Tapani Tiirola; Kari Pekka Pajukoski
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2014-08-29
Filing date: 2014-08-29
Publication date: 2016-03-03

Abstract

A method disclosed comprising selecting (201), in a network node, a predefined time unit PTU defining a maximum resource allocation unit in time in downlink. The network node schedules (202) one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU. Based on the scheduling, the network node causes (205) transmission of one or more messages to a terminal device by using a single carrier operation mode.

Description

DESCRIPTION

TITLE

CARRIER MODULATION IN COMMUNICATIONS

TECHNICAL FIELD

The invention relates to the field of cellular communication systems and, particularly, carrier modulation.

BACKGROUND

OFDM signals involve a high peak-to-average power ratio which may cause the clipping of peaks in transmitted signals due to a limited linear range of high power amplifiers. If the amplifier is operated only in a linear region, i.e. with a large output back-off, an undistorted signal can be transmitted. This, however, leads to a low signal-to-noise ratio in a receiver.

BRIEF DESCRIPTION

The invention is defined by the independent claims. Embodiments are defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 is illustrates a wireless communication system to which embodiments of the invention may be applied;

Figures 2 and 3 illustrate signalling diagrams of procedures for single carrier modulation according to an embodiment of the invention;

Figures 4 and 5 illustrate processes for single carrier modulation according to some embodiments of the invention;

Figure 6 illustrates resource allocation for a terminal device according to an embodiment of the invention; Figure 7 and 8 illustrate multiplexing within PTU according to some embodiments of the invention; Figures 9 and 10 illustrate blocks diagrams of apparatuses according to some

embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words "comprising" and "including" should be understood as not limiting the described embodiments to consist of only those features that have been mentioned and such embodiments may contain also features/structures that have not been specifically mentioned.

Figure 1 illustrates a wireless communication scenario to which embodiments of the invention may be applied. Referring to Figure 1 , a cellular communication system may comprise a radio access network comprising base stations disposed to provide radio coverage in a determined geographical area. The base stations may comprise macro cell base stations 102 arranged to provide terminal devices 106 with the radio coverage over a relatively large area spanning even over several square miles, for example. In densely populated hotspots where improved capacity is required, small area cell base stations 100 may be deployed to provide terminal devices 104 with high data rate services. Such small area cell base stations may be called micro cell base stations, pico cell base stations, or femto cell base stations. The small area cell base stations typically have significantly smaller coverage area than the macro base stations 102. The cellular communication system may operate according to specifications of the 3^rd generation partnership project (3GPP) long-term evolution (LTE) advanced or its evolution version. The physical layer of LTE is built on top of OFDMA (for downlink) and SC-FDMA (for uplink) technologies. OFDMA enables flexibility in frequency domain multiplexing, inter- symbol-interference ( IS I) free transmission, low-complexity reception (due to the fact that channel equalization may be made in subcarrier wise), and low-complexity MIMO extension. In addition to LTE downlink, OFDMA is adopted in many areas such as in digital TV (DVB-T and DVB-H) and wireless local area network (WLAN) applications.

OFDMA involves high peak-to-average power ratio (PAPR) of a transmitted signal which requires high linearity in the transmitter. An amplifier is to stay in a linear area with the use of extra power back-off in order to prevent problems to the output signal and spectrum mask. The use of additional back-off leads to reduced amplifier power efficiency or smaller output power. This may cause the range to be shortened, or when the same average output power level is maintained, the energy is consumed faster due to higher amplifier power consumption. The power efficiency is a reason why 3GPP decided to use OFDMA in the downlink direction but to use the power efficient SC-FDMA in the uplink direction. The power efficiency is used as a design parameter for mobile devices running on their own batteries and having a limited transmit power. A cubic metric (CM) difference between SC-FDMA and OFDMA is summarized in Table 1 below, wherein CM difference represents the difference in required output back-off (OBO). The CM difference translates into a corresponding difference in link budget and energy consumption. CM is a good measure for power amplifier efficiency especially on the uplink side, whereas OBO is a better measure on the downlink side.

Table 1

Regarding, power efficiency in LTE DL, the output back-off (OBO) has a direct impact to energy consumption. For example, assuming that 80 W linearized power requires a power amplifier with an input power of 480 W (3 x 160 W). For typical 3-sector base stations with two power amplifiers per sector, the linearized output power per base station site is 6 x 80 W = 480 W, and the input power per base station site is 6 x 3 x 160 W = 2,88 kW, wherein 10 000 base station sites consume 28,8 MW. Thus, a 3 dB reduction in the output back-off reduces the power consumption per site by 1 ,44 kW.

Power amplifier (PA) cost depends on the (linearized) output power. PA cost reduces quite slowly (in the order of a few percent/year) e.g. compared to the cost reduction of baseband processing. Hence, reducing the output back-off has a direct impact to the PA cost. E.g. the 3 dB reduction in the output back-off reduces the PA cost by 50%. For example, assuming a typical 3-sector base station with two power amplifiers per sector (80 W, a 55 $), the total cost of the power amplifiers is 330 $. Assuming that the output back-off is reduced by 3 dB, the total cost of the power amplifiers is reduced by 165 $/site. It is assumed that in DL side, OBO difference between a single carrier and OFDMA is even larger than a CM difference.

In the DL side, UEs share the same power amplifier resources (in UL, power amplifier resources are UE-specific). Thus, maintaining single carrier properties of multiplexed DL signals is a challenge. Furthermore, there is a link budget imbalance between UL and DL. This is due to the fact that transmit power difference between UE and eNB may be relatively large (e.g. up to 25 dB). Thus, having a common multiplexing design where single carrier transmission is applied in both UL and DL is a challenge.

In order to benefit from single carrier transmission, low peak-to-average power ratio (PAPR) property needs to be maintained not only when transmitting data and reference signals on physical uplink shared channel (PUSCH) but also when transmitting uplink controls signals with or without simultaneous UL data allocation. Separate control signalling schemes have been specified for different scenarios, such as control only (HARQ-ACK, HARQ-ACK+CSI, SRI), RS only, PUSCH data only, and various

combinations of them.

Modern cellular communication systems are wideband systems where a large bandwidth may be scheduled to a single terminal device for the transmission of data. The scheduled resources may be indicated (in frequency) in terms of physical resource blocks or frequency resource blocks. Each frequency resource block has a determined bandwidth and a centre frequency and one or more frequency resource blocks may be scheduled to the terminal device at a time. The frequency resource blocks scheduled to the terminal device may be contiguous and, thus, form a continuous scheduled band for the terminal device. However, the resource blocks may be non-contiguous in which case the form a non-contiguous band fragmented into a plurality of smaller bands. Let us now describe an embodiment of the invention for selecting and signalling link adaptation parameters with reference to Figures 2 and 3. Figures 2 and 3 illustrate signalling diagrams illustrating methods for communicating in a single carrier operation mode between a base station of a cellular communication system, e.g. base station 100 or 102, and a terminal device of the cellular communication system, e.g. the terminal device 104 or 106. In another embodiment, the procedures of Figures 2 and 3 may be carried out between the terminal device and an access node or, more generally, a network node. The network node may be a server computer or a host computer. For example, the server computer or the host computer may generate a virtual network through which the host computer communicates with the terminal device. In general, virtual networking may involve a process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization may involve platform virtualization, often combined with resource

virtualization. Network virtualization may be categorized as external virtual networking which combines many networks, or parts of networks, into the server computer or the host computer. External network virtualization is targeted to optimized network sharing.

Another category is internal virtual networking which provides network-like functionality to the software containers on a single system. Virtual networking may also be used for testing the terminal device.

Referring to Figure 2, a predefined time unit PTU defining a maximum resource allocation unit in time in downlink is selected in the base station (block 201 ). In block 202, the base station decides on a resource allocation by scheduling one or more terminal devices. A scheduling periodicity may be one predefined time unit PTU. Based on the scheduling, the base station may cause transmission of a control message to a terminal device, the control message comprising at least one information element indicating the resource allocation scheduled to the terminal device (step 203). In block 204, the terminal device acquires from the base station the control message comprising the at least one information element indicating the resource allocation scheduled to the terminal device. Based on the scheduling, the base station may cause transmission of one or more further messages to the terminal device by using a single carrier operation mode (step 205). The one or more further messages may comprise a data signal, control signal, a reference signal, or a signal or message of any other suitable signal/message type. In block 206, the terminal device acquires from the base station the one or more further message by using the single carrier operation mode.

Referring to Figure 3, a predefined time unit PTU defining a minimum resource allocation unit in time in uplink is selected in the base station (block 301 ). In block 302, the base station decides on a resource allocation by scheduling one or more terminal devices. A scheduling periodicity may be one predefined time unit PTU. Based on the scheduling, the base station may cause transmission of a control message to a terminal device, the control message comprising at least one information element indicating the resource allocation scheduled to the terminal device (step 303). In block 304, the terminal device acquires from the base station the control message comprising the at least one information element indicating the resource allocation scheduled to the terminal device. Based on the scheduling, the terminal device may cause transmission of one or more further messages to the base station by using a single carrier operation mode (step 305). The one or more further message may comprise a data signal, control signal, a reference signal, or a signal or message of any other suitable signal/message type. In block 306, the base station acquires from the terminal device the one or more further messages by using the single carrier operation mode.

In an embodiment, TDM scheduling is used in downlink.

In an embodiment, FDM scheduling is used in uplink. In an embodiment, a periodic control channel is included in the downlink in the predefined time unit (PTU). TDM is applied between the control channel and data channel(s).

In an embodiment, multiple user devices in uplink and downlink may be scheduled during one PTU. In an embodiment, HARQ-ACK timing and scheduling timing are defined to be a multiple of a predefined time unit PTU length (N x PTU, Νε [0, 1, 2, ... ] ).

In an embodiment, an operation mode is used which maintains single carrier properties in both UL and DL while maintaining link budget. This applies also in a scenario where eNB's Tx power is » UE's Tx power. When operating in this mode, only one signal at a time is transmitted via one Tx chain/antenna port. This applies to different signals and channels (including e.g. data channels, control channels, reference signals).

In an embodiment, the predefined time unit (PTU) defines a maximum periodicity for control channel transmission (in both UL and DL).

In an embodiment, in the downlink, multiplexing methods between UEs (UE#1 , UE#2) within PTU include TDM and spatial multiplexing (and/or spatial streams, in the form of SU-MIMO and MU-MIMO) (see Figure 6). An allocated resource may contain the entire system bandwidth in frequency (TDM only). In TDM/FDM, symbol level granularity may be applied in the resource allocation, wherein the allocated resource contains one or more (consecutive) symbols. The usage of FDM (parallel transmission) within PTU is limited to the case with multiple Tx chains (antenna ports), wherein different Tx chains may apply parallel transmission (i.e. FDM) for different UEs and/or DL channels. Both localized FDMA and IFDMA may be applied to facilitate FDMA. Spatial multiplexing is another form of parallel transmission. Spatial multiplexing may utilize a pre-coding operation

maintaining the single carrier (or low CM) properties of a transmitted signal. The pre- coding operation may cover both SU-MIMO and MU-MIMO.

In an embodiment, in the uplink, multiplexing methods between UEs within PTU include FDM and spatial multiplexing (see Figure 6). Different UEs may be multiplexed within PTU in frequency and/or space (MU-MIMO). Pre-coding and spatial multiplexing within UE may be based on codebooks maintaining the single carrier (or low CM) properties. PRB level granularity may be applied in the resource allocation, wherein an allocated resource contains one or more (consecutive) PRBs.

Thus, in an embodiment, FDM in DL is realized over antenna ports. In DL both MU-MIMO and SU-MIMO are realized such that single carrier properties are met. FDM and TDM are realized within similar sized PTU in both UL and DL. Figure 6 illustrates an exemplary resource allocation for a single user terminal (UE#1 ), covering both control signalling and data signalling. In the situation of Figure 6, control channel periodicity equals to 1 PTU, TDM is applied between control and data parts (in both UL and DL), a variable resource size in DL is achieved by means of varying single carrier symbol allocation, and block based processing is considered. In a typical case, cyclic prefix is included in each block. The minimum allocation unit in time (i.e. SC symbol in Figure 6) may also be more than one symbol (one symbol is assumed in Figure 6). Furthermore, the minimum allocation unit in time may or may not include a separate reference signal portion. For simplicity, reference signal portions are not shown in Figure 6. Variable resource size in UL is achieved by means of varying the PRB allocation. In the absence of the data part, the control channel is transmitted via a separate control channel resource (this is shown in UL, TTI(n+2)).

In an embodiment, the single carrier operation mode is realized on top of DFT-S-OFDMA, and the base station is configured to select between the SC mode and the OFDMA mode (either in a link specific manner, or jointly for both links).

In an embodiment, when multiplexing within PTU, there may be more than one Tx antenna/power amplifiers available for DL transmission in the base station. If pre-coded MIMO is used with one or more spatial layers, codebooks preserving a single carrier property of the transmitted message are applied in the pre-coding. In that case, the pre- coding covers both SU-MIMO and MU-MIMO, and the resource allocation in frequency may be common for different Tx antennas. Alternatively, if single carrier transmission is extended to support multiple simultaneous clusters or combs in the frequency domain (i.e. FDM), the maximum number of frequency domain clusters or combs corresponds to the number of Tx chains or antenna ports. These scenarios are depicted in Figure 7 for user terminals UEA, UEB. Spatial multiplexing corresponds to the SU-MIMO case. Localized FDMA utilizes frequency domain clusters. Interleaved FDMA (IFDMA) utilizes frequency domain combs.

In an embodiment, in case of the pre-coded MIMO, low CM codebooks are applied. In case of low CM codebooks (Rel-10, LTE UL SU-MIMO), only one layer is transmitted from one antenna port at a time. This is illustrated in Figure 8, and relates to LTE UL SU-MIMO codebook entries available for case of 4 Tx antennas and 3 spatial layers.

Thus, a considerable OBO reduction in the DL side (compared to LTE based on OFDMA) is obtainable, providing significant reduction in both energy consumption and the PA cost. A good link budget is obtainable in the UL side with a "clean control plane" arrangement. Bandwidth extension is obtainable in a cost efficient manner. The method and the system may be applied as a part of a massive MIMO 5G system, supporting power efficient single carrier transmission using a 5G air interface.

The term pre-coding is used herein to refer to beamforming for supporting multi-stream (or multi-layer) transmission in multi-antenna wireless communications. In conventional single-stream beamforming, the same signal is emitted from each of the transmit antennas with appropriate weighting (phase and gain) such that the signal power is maximized at the receiver output. When the receiver has multiple antennas, single-stream beamforming is not able to simultaneously maximize the signal level at each of the receive antennas. In order to maximize the throughput in multiple receive antenna systems, multi-stream transmission may be required.

In addition to/instead of the future 5G system, the method and the system may be applied in an evolution of LTE/LTE-A (e.g. Rel-13/Rel-14). The method and the system enable maintaining good capacity and coverage performance in different operating environments. The method and the system enable network operators to obtain energy savings, thus increasing profitability and friendliness to the environment.

Let us now describe some embodiments with reference to Figures 4 and 5. Figures 4 and 5 illustrate embodiments for single carrier modulation. Referring to Figure 4, the base station may select a predefined time unit PTU defining a maximum resource allocation unit in time in downlink (block 401 ). In block 402, the base station may decide on a resource allocation by scheduling one or more terminal devices, such that a scheduling periodicity is one predefined time unit PTU. Based on the scheduling, the base station may cause transmission of a control message to a terminal device, the control message comprising at least one information element indicating the resource allocation scheduled to the terminal device (block 403). Further, based on the scheduling, the base station may cause transmission of one or more further messages to the terminal device by using a single carrier operation mode (block 404). The one or more further message may comprise a data channel message, control channel message, a reference signal, or a signal or message of any other suitable signal/message type. Alternatively, in block 401 , the base station may select a predefined time unit PTU defining a minimum resource allocation unit in time in uplink, wherein, in block 404, the base station acquires from the terminal device one or more further messages by using the single carrier operation mode.

Referring to Figure 5, the terminal device may acquire from the base station a control message comprising at least one information element indicating the resource allocation scheduled to the terminal device (block 501 ). In block 502, the terminal device acquires from the base station one or more further messages by using a single carrier operation mode. The one or more further messages may comprise a data channel message, control channel message, a reference signal, or a signal or message of any other suitable signal/message type.

Alternatively, in block 502, the terminal device causes transmission of the one or more further messages to the base station by using the single carrier operation mode.

In an embodiment, the embodiments of Figures 4 and 5 may be combined. For example, both criteria may be fulfilled to select one scheme, e.g. the number of connected terminal devices must be below the threshold and the coherence bandwidth below the bandwidth of the operating band in order to select the frequency-selective link adaptation scheme. In a further modification, the processes of Figures 4 and/or 5 may be exclusive to macro base stations, e.g. the base station 102 may carry out the embodiments of Figure 2, 3, 4 and/or 5 but the small cell base station 100 may not (or vice versa).

An embodiment provides an apparatus comprising at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to carry out the procedures of the above-described base station or the network node. The at least one processor, the at least one memory, and the computer program code may thus be considered as an embodiment of means for executing the above- described procedures of the base station or the network node. Figure 9 illustrates a block diagram of a structure of such an apparatus. The apparatus may be comprised in the base station or the network node, e.g. the apparatus may form a chipset or a circuitry in the base station or the network node. In some embodiments, the apparatus is the base station or the network node. The apparatus comprises a processing circuitry 10 comprising the at least one processor. The processing circuitry 10 may comprise a PTU selector 18 configured to select a predefined time unit PTU defining a maximum resource allocation unit in time in downlink. The apparatus may further comprise a scheduler circuitry 14 configured to schedule frequency resource blocks in transmission time intervals to the terminal devices. The scheduler circuitry 14 may output to a control message generator

(not shown in Figure 9) information on the schedulings and the control message generator may create the scheduling messages indicating the schedulings to terminal devices on a control channel. The PTU selector 18 may be configured to output the predefined time unit PTU to the scheduler 14. The scheduler may be configured to schedule one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU. Upon scheduling the user terminals, the scheduler may output a signal indicating a scheduled resource allocation to a message generator 12 configured to generate one or more further messages to a terminal device by using a single carrier operation mode. In another embodiment, the PTU selector 18 is configured to select a predefined time unit PTU defining a minimum resource allocation unit in time in uplink. The processing circuitry 10 may comprise the circuitries 12 to 18 as sub-circuitries, or they may be considered as computer program modules executed by the same physical processing circuitry. The memory 20 may store one or more computer program products 24 comprising program instructions that specify the operation of the circuitries 12 to 18. The memory 20 may further store a database comprising definitions for the selection of the link adaptation scheme, for example. The apparatus may further comprise a communication interface 22 providing the apparatus with radio communication capability with the terminal devices. The communication interface 22 may comprise a radio communication circuitry enabling wireless communications and comprise a radio frequency signal processing circuitry and a baseband signal processing circuitry. The baseband signal processing circuitry may be configured to carry out the functions of the transmitter and/or the receiver, as described above in connection with Figures 1 to 9. In some embodiments, the communication interface may be connected to a remote radio head comprising at least an antenna and, in some embodiments, radio frequency signal processing in a remote location with respect to the base station. In such embodiments, the communication interface 22 may carry out only some of radio frequency signal processing or no radio frequency signal processing at all. The connection between the communication interface 22 and the remote radio head may be an analogue connection or a digital connection. An embodiment provides another apparatus comprising at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to carry out the procedures of the above-described terminal device. The at least one processor, the at least one memory, and the computer program code may thus be considered as an embodiment of means for executing the above-described procedures of the terminal device. Figure 10 illustrates a block diagram of a structure of such an apparatus. The apparatus may be comprised in the terminal device, e.g. it may form a chipset or a circuitry in the terminal device. In some embodiments, the apparatus is the terminal device. The apparatus comprises a processing circuitry 50 comprising the at least one processor. The processing circuitry 50 may comprise a communication controller circuitry 54 configured to extract scheduling messages received from a serving base station, to determine communication resources scheduled to the terminal device, e.g. frequency resource block(s) and associated transmission time intervals, and to control the terminal device to transmit or receive data between the base station in the scheduled communication resources. The apparatus may further comprise a message generator 52 configured to transfer one or more further messages to the network node by using a single carrier operation mode.

The processing circuitry 50 may comprise the circuitries 52, 54 as sub-circuitries, or they may be considered as computer program modules executed by the same physical processing circuitry. The memory 60 may store one or more computer program products

64 comprising program instructions that specify the operation of the circuitries 52, 54. The apparatus may further comprise a communication interface 62 providing the apparatus with radio communication capability with base stations of one or more cellular

communication networks. The communication interface 62 may comprise a radio communication circuitry enabling wireless communications and comprise a radio frequency signal processing circuitry and a baseband signal processing circuitry. The baseband signal processing circuitry may be configured to carry out the functions of the transmitter and/or the receiver, as described above in connection with Figures 2 to 10.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware- only circuit implementations such as implementations in only analog and/or digital circuitry; (b) combinations of circuits and software and/or firmware, such as (as applicable): (i) a combination of processor(s) or processor cores; or (ii) portions of processor(s)/software including digital signal processor(s), software, and at least one memory that work together to cause an apparatus to perform specific functions; and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of 'circuitry' applies to all uses of this term in this application. As a further example, as used in this application, the term "circuitry" would also cover an

implementation of merely a processor (or multiple processors) or portion of a processor, e.g. one core of a multi-core processor, and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular element, a baseband integrated circuit, an application-specific integrated circuit (ASIC), and/or a field-programmable grid array (FPGA) circuit for the apparatus according to an embodiment of the invention.

The processes or methods described above in connection with Figures 2 to 10 may also be carried out in the form of one or more computer process defined by one or more computer programs. The computer program shall be considered to encompass also a module of a computer programs, e.g. the above-described processes may be carried out as a program module of a larger algorithm or a computer process. The computer program(s) may be in source code form, object code form, or in some intermediate form, and it may be stored in a carrier, which may be any entity or device capable of carrying the program. Such carriers include transitory and/or non-transitory computer media, e.g. a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package. Depending on the processing power needed, the computer program may be executed in a single electronic digital processing unit or it may be distributed amongst a number of processing units.

The present invention is applicable to cellular or mobile communication systems defined above but also to other suitable communication systems. The protocols used, the specifications of cellular communication systems, their network elements, and terminal devices develop rapidly. Such development may require extra changes to the described embodiments. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

List of abbreviations

3GPP third generation partnership project

ACK acknowledgement

DL downlink eNB enhanced node-B, base station

LTE long term evolution

OFDM orthogonal frequency division multiplexing

OFDMA OFDM access

TDD time division duplex

UL uplink

5G 5th generation

CM cubic metric

CSI channel state information

DVB-T digital video broadcasting terrestrial

DVT-H digital video broadcasting handheld

FDM frequency division multiplexing

FDMA FDM access

HARQ hybrid automatic repeat request

ISI inter symbol interference

MIMO multiple input multiple output

MU multi user

OBO output back-off PA power amplifier

PAPR peak-to-average power ratio

PAR peak-to-average ratio

PRB physical resource block

PSK phase shift keying

PTU predefined time unit

PUSCH physical uplink shared channel

QAM quadrature amplitude modulation

RS reference signal

SC-FDMA single carrier FDMA

SRI scheduling request indicator

SU single user

TDM time division multiplexing

TV television

Tx transmitter

WLAN wireless local area network

UE user equipment

I FDMA interleaved FDMA

DFT discrete Fourier transform

IFFT inverse fast Fourier transform

CP cyclic prefix

Ant. antenna

Freq. frequency

Claims

1 . A method comprising: selecting, in a network node, a predefined time unit PTU defining a maximum resource allocation unit in time in downlink; scheduling, in the network node, one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU; and based on the scheduling causing, in the network node, transmission of one or more messages to a terminal device by using a single carrier operation mode.

2. A method comprising: selecting, in a network node, a predefined time unit PTU defining a minimum resource allocation unit in time in uplink; scheduling, in the network node, one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU; and based on the scheduling acquiring, in the network node, one or more messages from a terminal device by using a single carrier operation mode.

3. The method of claim 1 or 2, wherein the single carrier operation mode corresponds to a transmission scheme where for each antenna port only one modulated symbol is transmitted at a time.

4. The method of claim 1 , 2 or 3, further comprising using time division multiplexing between parallel channels in downlink and frequency division multiplexing between parallel channels in uplink.

5. The method of any of claims 1 to 4, further comprising determining that HARQ-ACK timing and scheduling timing are a multiple of a predefined time unit PTU length.

6. The method of any of claims 1 to 5, further comprising using, in the downlink, TDM as a multiplexing procedure between user terminals within the predefined time unit PTU.

7. The method of any of claims 1 to 5, further comprising using, in the downlink, spatial multiplexing and/or spatial streams in the form of SU-MIMO and/or MU-MIMO as a multiplexing procedure between user terminals within the predefined time unit PTU.

8. The method of any of claims 1 to 7, further comprising using, in the uplink, FDM as a multiplexing procedure between user terminals within the predefined time unit PTU.

9. The method of any of claims 1 to 8, further comprising using, in the uplink, spatial multiplexing as a multiplexing procedure between user terminals within the predefined time unit PTU.

10. The method of any of claims 1 to 9, further comprising, if pre-coded MIMO is used with one or more spatial layers, codebooks preserving a single carrier property of the transmitted message are applied in the pre-coding.

1 1 . The method of any of claims 1 to 9, wherein, if single carrier transmission is extended to support multiple simultaneous clusters or combs in a frequency domain, the maximum number of frequency domain clusters or combs corresponds to the number of Tx chains or antenna ports.

12. A method comprising: acquiring, in a terminal device, a control message from a network node, the control message comprising at least one information element indicating a resource allocation scheduled to the terminal device, in which a scheduling periodicity is one predefined time unit PTU defining a maximum resource allocation unit in time in downlink; and based on the acquiring acquiring, in the terminal device, one or more further messages from the network node by using a single carrier operation mode.

13. A method comprising: acquiring, in the terminal device, a control message from a network node, the control message comprising at least one information element indicating a resource allocation scheduled to the terminal device, in which a scheduling periodicity is one predefined time unit PTU defining a minimum resource allocation unit in time in uplink; and based on the acquiring causing, in the terminal device, transmission of one or more further messages to the network node by using a single carrier operation mode.

14. An apparatus comprising: at least one processor; and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: select a predefined time unit PTU defining a maximum resource allocation unit in time in downlink; schedule one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU; and based on the scheduling cause transmission of one or more messages to a terminal device by using a single carrier operation mode.

15. An apparatus comprising: at least one processor; and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: select a predefined time unit PTU defining a minimum resource allocation unit in time in uplink; schedule one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU; and based on the scheduling acquire one or more messages from a terminal device by using a single carrier operation mode.

16. The apparatus of claim 14 or 15, wherein the single carrier operation mode

corresponds to a transmission scheme where for each antenna port only one modulated symbol is transmitted at a time.

17. The apparatus of claim 14, 15 or 16, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to use time division multiplexing between parallel channels in downlink and frequency division multiplexing between parallel channels in uplink.

18. The apparatus of any of claims 14 to 17, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to determine that HARQ-ACK timing and scheduling timing are a multiple of a predefined time unit PTU length.

19. The apparatus of any of claims 14 to 18, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to use, in the downlink, TDM as a multiplexing procedure between user terminals within the predefined time unit PTU.

20. The apparatus of any of claims 14 to 18, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to use, in the downlink, spatial multiplexing and/or spatial streams in the form of SU-MIMO and/or ML) -Ml MO as a multiplexing procedure between user terminals within the predefined time unit PTU.

21 . The apparatus of any of claims 14 to 20, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to use, in the uplink, FDM as a multiplexing procedure between user terminals within the predefined time unit PTU.

22. The apparatus of any of claims 14 to 20, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to use, in the uplink, spatial multiplexing as a multiplexing procedure between user terminals within the predefined time unit PTU.

23. The apparatus of any of claims 14 to 22, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to apply codebooks preserving a single carrier property of the transmitted message in the pre-coding, if pre-coded MIMO is used with one or more spatial layers.

24. The apparatus of any of claims 14 to 23, wherein, if single carrier transmission is extended to support multiple simultaneous clusters or combs in a frequency domain, the maximum number of frequency domain clusters or combs corresponds to the number of Tx chains or antenna ports.

25. An apparatus comprising: at least one processor; and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: acquire a control message from a network node, the control message comprising at least one information element indicating a resource allocation scheduled to the terminal device, in which a scheduling periodicity is one predefined time unit PTU defining a maximum resource allocation unit in time in downlink; and based on the acquiring acquire, one or more further messages from the network node by using a single carrier operation mode.

26. An apparatus comprising: at least one processor; and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: acquire a control message from a network node, the control message comprising at least one information element indicating a resource allocation scheduled to the terminal device, in which a scheduling periodicity is one predefined time unit PTU defining a minimum resource allocation unit in time in uplink; and based on the acquiring cause transmission of one or more further messages to the network node by using a single carrier operation mode.

27. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into an apparatus, execute the method according to any preceding claim 1 to 12.

28. A computer program product embodied on a non-transitory distribution medium readable by a computer and comprising program instructions which, when loaded into the computer, execute a computer process comprising: selecting, in a network node, a predefined time unit PTU defining a maximum resource allocation unit in time in downlink; scheduling, in the network node, one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU; and based on the scheduling causing, in the network node, transmission of one or more messages to a terminal device by using a single carrier operation mode.

29. A computer program product embodied on a non-transitory distribution medium readable by a computer and comprising program instructions which, when loaded into the computer, execute a computer process comprising: selecting, in a network node, a predefined time unit PTU defining a minimum resource allocation unit in time in uplink; scheduling, in the network node, one or more terminal devices such that a scheduling periodicity is one predefined time unit PTU; and based on the scheduling acquiring, in the network node, one or more messages from a terminal device by using a single carrier operation mode.