Enhancing data transfer

There is provided a method comprising: obtaining, by an apparatus, a first data block, a second data block and a third data block; generating a first signal, wherein a first part of the first signal is generated based on a data of the first data block, and wherein a second part of the first signal is generated based on a data of the second data block, the second part being subsequent in time domain compared with the first part; generating a second signal, wherein a first part of the second signal is generated based on a data of the third data block, and wherein a second part of the second signal is generated based on the data of the second data block, the second part being subsequent in time domain compared with the first part; and transmitting the first and second signals.

RELATED APPLICATION

This application was originally filed as PCT Application No. PCT/EP2015/061006 filed May 19, 2015.

TECHNICAL FIELD

The invention relates to communications.

BACKGROUND

The number of terminal devices used for different communication purposes within radio communication networks is increasing. Enhancing the radio communication networks ability to handle increased amount of traffic on a wireless radio channel may increase the overall performance of the system.

BRIEF DESCRIPTION

According to an aspect, there is provided the subject matter of the independent claims. Some embodiments are defined in the dependent claims.

One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Embodiments described may be implemented in a radio system, such as in at least one of the following: Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and/or 5G system. The present embodiments are not, however, limited to these systems.

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties. One example of a suitable communications system is the 5G concept, as listed above. It is assumed that network architecture in 5G will be quite similar to that of the LTE-advanced. 5G is likely to use multiple input-multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates. 5G will likely be comprised of more than one radio access technology (RAT), each optimized for certain use cases and/or spectrum.

FIG. 1illustrates an example of a radio system to which embodiments of the invention may be applied. Referring toFIG. 1, radio communication networks, such as the Long Term Evolution (LTE), the LTE-Advanced (LTE-A) of the 3rdGeneration Partnership Project (3GPP), or the predicted future 5G solutions, are typically composed of at least one network element, such as a network element102, providing a cell104. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico-cell, for example. The network element102may be an evolved Node B (eNB) as in the LTE and LTE-A, a radio network controller (RNC) as in the UMTS, a base station controller (BSC) as in the GSM/GERAN, or any other apparatus capable of controlling radio communication and managing radio resources within a cell. For 5G solutions, the implementation may be similar to LTE-A, as described above. The network element102may be a base station or a small base station, for example. In the case of multiple eNBs, or similar, in the communication network, the eNBs may be connected to each other with an X2 interface as specified in the LTE. Other communication methods between the network elements may also be possible.

The network element102may be further connected via an S1 interface to an evolved packet core (EPC)130, more specifically to a mobility management entity (MME) and to a system architecture evolution gateway (SAE-GW).

The cell104may provide service for at least one terminal device110,120, wherein the at least one terminal device110,120may be located within and/or comprised in the cell104. The at least one terminal device110,120may communicate with the network element102using a communication link(s)116,126, which may be understood as communication link(s) for end-to-end communication, wherein source device transmits data to the destination device via the network element102and/or core network. The communication link(s)116,126may be controlled by the network element102. This may mean that resource allocation, such as Physical Resource Block (PRB) allocation, may be decided by the network element102. Resource allocation may be based on data from the network element102and/or the data from the at least one terminal device110,120. For example, Channel Quality Indicators (CQI) may be received from the at least one terminal device110,120.

The at least one terminal device110,120may reside within some distance from the network element102, and thus different terminal devices110,120may be within different distances from the network element102.

Further, it is possible that there are other cells in the area of the cell104. The other cells may be at least partially in the area of the cell104. The other cells may be provided, for example, by other network elements providing macro, micro, pico and/or femto cells. The at least one terminal device110,120may be simultaneously within multiple cells provided by the other network elements. The serving network element may be selected by various criteria, such as received power, signal to noise ratio (SNR) and path loss, to name a few.

The at least one terminal device110,120may be a terminal device of a radio system, e.g. a computer (PC), a laptop, a palm computer, a mobile phone, a smart phone, a tablet, a phablet or any other user terminal or user equipment capable of communicating with the radio communication network. The at least one terminal device110may be stationary or on the move.

The network element102, the at least one terminal device110,120and/or the other network elements may support Dual Connectivity (DC) or similar, and/or Multiple Input Multiple Output (MIMO) connectivity. Thus, for example, data may be transmitted by multiple network elements and/or data may be transmitted by a single network element using multiple antennas for the transmission, wherein the transmission may be substantially simultaneous. Naturally, the receiver may comprise, for example, multiple antennas and/or communication circuitries that are able to detect and/or receive the transmissions from multiple sources.

In an embodiment, the at least one terminal device110,120is able to communicate with other similar devices via the network element102. The other devices may be within the cell104and/or may be within other cells provided by other network elements.

In an embodiment, the at least one terminal device110,120may communicate directly with other terminal devices using, for example, Device-to-Device (D2D) communication. For example, inFIG. 1, a first terminal device110may communicate (e.g. transfer information) with a second terminal device120using a D2D communication link121between the devices, and vice versa. This may enhance the performance of the radio communication network.

As there is at least some distance between terminal devices110,120and the network element102, providing the cell104, communication links116,126,121may suffer from time dispersion of wireless signals used to transmit and receive information. Further, as the distances may vary between devices, time dispersion may become an increasing concern.

Time dispersion characteristics of a wireless channel(s), comprised in the communication links116,126,121, may introduce inter-symbol interference (ISI) in the received signal, which may reduce change for correct detection of the transferred information by the receiver. For example, if the network element102transmits data to the first terminal device110, the terminal device110may receive the same transmitted sub-carrier signal from multiple paths. The signal may be, for example, travel directly to the first terminal device110and/or it may bounce one or more times from objects and/or different layers of atmosphere.

The effects of the ISI may be countered using a guard period between adjacent time symbols. Nonetheless, such guard period may introduce and/or increase a radio communication system overhead which may increase linearly with the delay spread of the channel. For example, in Orthogonal Frequency Division Multiplexing (OFDM) systems, the guard period may be replaced by a Cyclic Prefix (CP) that may be obtained as a copy of a last part of the time symbol, and appended at the beginning of the time symbol itself. The CP may allow converting the linear convolution with the channel to a circular convolution, thus enabling low complexity one-tap frequency domain equalization. The CP is typically hardcoded in the system numerology and its duration is defined as a compromise between the necessity of coping with radio channels experiencing different propagation characteristics, and maintaining a reasonable overhead. The reason for the hard-coding may be to ensure the same performance over the entire cell coverage area (e.g. coverage area of cell104) while maintaining orthogonality between scheduled users (e.g. at least one terminal device110,120). From a system perspective, the CP represents pure (e.g. undesired) overhead, and is discarded at the receiver.

In high-Doppler environments, an LTE uplink (UL) performance may suffer from performance degradation. The reason for such degradation may be that a rate of reference symbol (RS) transmission struggles to cope with fast changes of the wireless radio channel. For example, in high Doppler environments, the radio channel at one end of the slot may have little correlation with the channel at another end of the slot, and thus, applying a single channel estimate for data demodulation may become increasingly problematic as the terminal device speed grows.

Zero Tail Discrete Fourier Transform-spread OFDM (ZT DTF-s-OFDM) signal(s) convert the CP to a low power tail which may be a part of the Inverse Fast Fourier Transform (IFFT) output, and may also meant to cope with the delay spread of the wireless radio channel. The main advantage of the ZT DFT-s-OFDM signal, with respect to traditional CP-OFDM, may be the possibility of dynamically adjusting tail duration of the signal depending on the estimated characteristics of the multipath wireless radio channel. However, even though adaptive, the low power tail may still provide overhead in the radio communication system perspective.

Emerging waveforms, such as Generalized Frequency Division Multiplexing (GFDM) or Filter Bank Multicarrier (FBMC) may have the promise of eliminating the CP overhead due to well-designed shaping filter applied at each subcarrier of the signal, which may reduce the impact of the ISI. Nonetheless, such waveforms may still require some time domain overhead for accommodating the tails of the filter or complex iterative process at the receiver to restore the orthogonality of the frequency resources.

Regarding the performance degradation for high speed mobiles, there may be few options, such as adding an additional reference block (e.g. Reference Symbol (RS)). This may however create a RS overhead. By introducing an additional RS DFT-s-OFDMA symbol, the terminal device throughput may drop by about 20%, since there would be, for example, only 5 instead of 6 data DFT-s-OFDMA symbols.

Second option may be to divide some DFT-s-OFDMA symbols to portions and to piggy-back RS signal with the data transmission in a portion of DFT-s-OFDMA symbol. The problem with this option may be the increased overall CP overhead since the number of CPs may increase.

There is provided a solution to enhance the performance of the radio communication system by converting, at least partly, the system overhead into useful information, while preserving, at least partly, robustness of the wireless radio channel to the delay spread. A new signal form may be introduced as a part of the solution.

FIG. 2illustrates a block diagram according to an embodiment of the invention. Referring toFIG. 2, in step202, an apparatus, such as the at least one terminal device110,120, the network element102, a communication circuitry comprised in the at least one terminal device110,120, and/or a communication circuitry comprised in the network element102, may obtain a first data block, a second data block and a third data block. The data blocks may comprise information that is to be delivered from a transmitting device to a receiving device.

In step204, the apparatus may generate a first signal, wherein a first part of the first signal is generated based on a data of the first data block, and wherein a second part of the first signal is generated based on a data of the second data block, the second part of the first signal being subsequent in time domain compared with the first part of the first signal.

Similarly, in step206, the apparatus may generate a second signal, wherein a first part of the second signal is generated based on a data of the third data block, and wherein a second part of the second signal is generated based on the data of the second data block, the second part of the second signal being subsequent in time domain compared with the first part of the second signal.

The generation of the first and second signals based on the data of the first, second and third data blocks may mean that the data of the data blocks is comprised in the first and second signals as described above. For example, if the first data block comprises binary number 0100110, the generated first part of the first signal may comprise said binary number. This may mean that when the first signal is received, the receiver may modulate the received signal to back into the binary form comprising said binary number.

Further, as the second parts of the first and second signals may be generated based on the data of the second data block, the second parts of the first and second signals may comprise at least partially the same data. In an embodiment, the second parts of the first and second signal are generated based on the same data. In an embodiment, the second parts of the first and second signals are substantially identical. Thus, the second parts of the first and second signals may be generated from the data of the second data block. In other words, the second parts of the first and second signals may be generated using the data of the second data block as an input.

In step208, the apparatus may transmit or cause transmission of the first and second signals. The transmitting, by the apparatus, may comprise transmitting the first signal and/or the second signal to a receiving apparatus, which may be similar as the transmitting apparatus. For example, the at least one terminal device110,120may transmit the first signal and the second signal to the network element102, and/or vice versa. It may also be possible that the transmitting comprises broadcasting the first and/or second signals. For example, the network element102may broadcast the first and second signals to a plurality of terminal devices. In another example, the at least one terminal device110,120may broadcast the first and second signals to the plurality of terminal devices.

In an embodiment, the first signal is a first multicarrier signal. In another embodiment, the first signal is a first single-carrier signal.

In an embodiment, the second signal is a second multicarrier signal. In another embodiment, the second signal is a second single-carrier signal. In the following, some embodiments are described in the context of the multicarrier signals but the embodiments are applicable to the single-carrier signals as well.

In an embodiment, the apparatus broadcasts at least one of the second portion of the first multicarrier signal, the second portion of the second multicarrier signal. In such case, it may be possible that the apparatus either transmits or broadcasts the first portions of the signals. Further, it is possible that one of the first portion of the first multicarrier signal and the first portion of the second multicarrier signal may be broadcasted, whereas the other first portion may be transmitted using end-to-end type communication (i.e. unicast). For example, the first and third parts may have different receivers. Similarly, the first and third parts may be transmitted to one receiver. In such case, the second parts may be transmitted to the same receiver (to which the first and/or third parts are transmitted to) or to different receiver(s).

The second parts of the first and second multicarrier signals may be conventionally considered to be radio communication system overhead. The present solution enables to use the second parts to carry useful information while still maintaining the robustness to the delay spread. For example, the first parts of the signals may be varying between the signals. Thus, the first multicarrier signal may carry different data compared with the second multicarrier signal. However, the second parts of the signals may be fixed between the signals as they may be generated based on the same data. The second parts of the signals may be located in place of the guard periods, and may be repeated for a set of consecutive signals. For example, the apparatus may generate 14 signals each representing one fixed-tail (FT) DFT-s-OFDM symbol, wherein the second parts of said 14 signals may be fixed and/or generated based on the same data, such as the data of the second data block. Thus, the same fixed part and/or fixed-tail may be repeated for, for example, duration of a sub-frame (i.e. LTE subframe).

Let us assume, for example, that the wireless radio channel is slowly varying over a set of consecutive symbols (i.e. FT DFT-s-OFDM symbols). As explained above, a symbol may be represented by a multicarrier signal, such as the first and/or the second multicarrier signals. In a way, it may be understood that the information comprised in the symbol may be carried by the signal. In case the length of a second part of the symbol (e.g. the second part of the multicarrier signal) is sufficient to cope with an excess delay spread of the wireless radio channel, the cyclicity of the signal may be preserved at the receiver and traditional low complexity one-tap frequency domain equalization may be performed. This may be because each symbol may experience from the previous symbol the similar delay spread component, or ISI, that itself is creating to the next symbol. This may allow restoring a similar situation compared with the traditional CP-based transmission (i.e. the copy of the last portion of the symbol appended at its beginning).

Therefore, the receiver of the first and second multicarrier signals may use the repeated second parts of the signals similar to a situation of using the CP. However, as the second parts of the first and second multicarrier signals are transmitted by the transmitter, the receiver may also use the received second parts of said signals instead of omitting them, and thus useful information may be transferred and the delay spread may still be handled by the receiver. Further, the second parts may be comprised in the tails of the multicarrier signals. For example, a last part of a multicarrier signal, such as a tail of the first multicarrier signal, may extend, in time domain, over the second multicarrier signal. However, using the above method the interference caused by the tail may be reduced and/or removed, and as said, useful information may be transmitted.

There is also provided a signal comprising: a first multicarrier signal, wherein a first part of the first multicarrier signal is generated from a data of a first data block, wherein a second part of the first multicarrier signal is generated from a data of a second data block, and wherein the second part of the first multicarrier signal is subsequent in time domain compared with the first part of the first multicarrier signal, and a second multicarrier signal, wherein a first part of the second multicarrier signal is generated from a data of a third data block, wherein a second part of the second multicarrier signal is generated from the data of the second data block, and wherein the second part of the second multicarrier signal is subsequent in time domain compared with the first part of the second multicarrier signal. Said signal may be transmitted by the apparatus and received by another. For example, the first terminal device110may transmit the signal to the network element102, and/or vice versa.

Let us now look closer on embodiments of the invention.FIGS. 3A to 3Cillustrate some embodiments. Referring toFIG. 3A, an example of generating a multicarrier signal340according to an embodiment may be shown. As described earlier, the multicarrier signal340, such as the first and/or second multicarrier signals, may comprise a first part and a second part. InFIG. 3A, the first part may be a first part342, and the second part may be a second part344. The second part344may be a fixed part as it may be fixed between two or more signals each representing a time domain symbol. Similarly, the first part may a variable part as it may change between time domain symbols or signals. Thus, the second part344may be referred also a fixed part and the first part may be referred to as a variable part.

In an embodiment, the second part344is a fixed part. The first part342may be a variable part. The second part344may be, for example, constant in time (i.e. reference signals), it may be varying in time, but constant for a number of consecutive FT DFT-s-OFDM symbols (i.e. reference symbols or low rate signaling, such as ACK/NACK, or Channel Quality Indicator (CQI) information).

The second part344of the multicarrier signal340may be a tail of the multicarrier signal340, for example. This may mean that the second part344extends, in time domain, from the end of the multicarrier signal340towards the beginning of said signal. For example, if we consider multiple subcarriers that are comprised in the multicarrier signal340, the tail of the multicarrier signal340may comprise tail of at least one subcarrier signal.

In an embodiment, the second parts of the first and second multicarrier signals, described above, are tails of said signals, and wherein said signals are fixed-tail multicarrier signals. Example of this is given in relation to multicarrier signal340. This may mean that at the receiver, for example, the second part344, transmitted by the transmitter, may be detected and/or received as the tail of the multicarrier signal340. As described, the tail may extend at least partially over the next time symbol.

If we look closer on how the signals are formed in the example ofFIG. 3A, a number of data inputs302,304may be used.FIG. 3Amay be understood to shown how each multicarrier signal is generated. In other words, the modulation and transformation of the data to a signal may be performed signal by signal. The generation may comprise using Discrete Fourier Transform (DFT)310, subcarrier mapping320and/or Inverse Fast Fourier Transform (IFFT)330. Each step may be performed by a dedicated circuitry, for example. For example, the apparatus described in relation toFIG. 2, may comprise a DFT circuitry, a subcarrier mapping circuitry, and IFFT circuitry. It may also be possible that the apparatus comprises a communication circuitry capable and/or configured at least to perform the steps310,320,330shown inFIG. 3A.

As shown, the data inputs302,304may be used as inputs to the signal generation. Outputs of the DFT310may be modulated and/or channel coded. After modulation, in subcarrier mapping, the modulated and/or channel coded outputs may be mapped to subcarriers. After the subcarrier mapping, the multicarrier signal340may be generated by transforming the frequency domain representation to time domain using the IFFT330.

The first part342of the multicarrier signal340may be generated from a data of a first data block302, whereas the second part344may be generated from a data of the second block304. This is similar as described in relation toFIG. 2.

In an embodiment, the second data block304comprises samples each having power that differs substantially from zero. That is, the data of the second data block304may comprise values that are not representing zero power. In other words, the samples in the second data block304may comprise information. In an embodiment, the second data block304comprises at least one sample that is substantially zero and/or very low power.

In an embodiment, the tails of the first and second multicarrier signal are generated from the data of the second data block, described in relation toFIG. 2, and wherein the tails of the first and second multicarrier signal comprise the same data. For example, inFIG. 3A, the second part344may be generated from the second data block304. Similarly, if further signals are generated, the tails of the signals may comprise the same data, whereas the first parts (i.e. first part342) may be varying between signals.

In an embodiment, the multicarrier signal340and/or the first and second signals, described in relation toFIG. 2, are FT DTF-s-OFDM signals.

Referring toFIG. 3B, a sequence of consecutive multicarrier signals352,354,356may be shown. In this example, three consecutive signals may be shown, but as described, the number of generated signals may be more or less, for example, 2, 7, 14 signals, but not limited to these numbers.

As inFIG. 3A, a first, second and/or third multicarrier signals352,354,356may each comprise the first part342and the second part344. A delay spread362of the signals may be shown inFIG. 3B. Each signal may cause interference to at least adjacent signals. However, as the invention proposes, these delay spreads362may be handled by repeating the second part344between the signals, and further this enables carrying information in the second part344.

In an embodiment, the first part342of the first multicarrier signal352is longer in time domain compared with the second part344of the first multicarrier signal352. Similarly, the first parts of the second and third multicarrier signals354,356may be longer compared with the second parts. However, the duration of the first part and/or the second part may vary between the multicarrier signals352,354,356. For example, the second part of the second multicarrier signal354may be longer compared with the second part of the first multicarrier signal352.

In an embodiment, the apparatus is capable of changing the duration or length of the second part344. The duration may be changed for each signal such that the duration of the second part344may vary between consecutive signals. Naturally it is possible that duration of each signal comprising the same second part may be changed. Thus, for example, two consecutive signals comprising the same second part may be generated so that the duration of the second parts is the same between said two consecutive signals.

In an embodiment, the first and second multicarrier signals352,354are transmitted consecutively in time domain. Naturally, the third multicarrier signal356may be transmitted after the second multicarrier signal, if there are more than two multicarrier signals to be transmitted. Further, the apparatus may transmit a plurality of multicarrier signals consecutively, wherein each signal of the plurality of multicarrier signals comprises the same second part. In an embodiment, the plurality of multicarrier signals are transmitted substantially simultaneously.

Referring toFIG. 3C, the second parts of the first, second and/or third multicarrier signals may be used to transmit control message(s). For example, the apparatus may transmit a control message to another apparatus using the second parts. In an embodiment, the second data block304ofFIG. 3Acomprises the control message. Thus, one or more multicarrier signals352,354,356may be used to carry the control message to the receiving apparatus.

In the example ofFIG. 3C, the second part of each multicarrier signal352,354,356may comprise an Acknowledgement (ACK) message. Similarly, Negative Acknowledgement (NACK) message may be transmitted. It needs to be noted again that although three signals are shown, the solution may be applicable to two or more signals. Naturally, only one signal may be formed. However, this may not bring the same benefits as using two or more signals due to the absence of repetition of the second part.

The control message comprised in the second data block304may be related to channel estimation, phase noise and frequency offset estimation, and/or data receiving acknowledgement (i.e. ACK/NACK), for example. However, these are only examples, and thus the control message may comprise and/or be related to virtually any control message that may be transmitted from the apparatus to another apparatus using a signal. For example, let us consider a case where the network element102wants to provide a configuration control message towards a terminal device and uses this approach to convey the information. In one example, paging information or system information is transmitted by the network element102to the terminal device. Also, for the uplink direction, the terminal device may transmit, for example, buffer status reports and/or advanced scheduling requests to the network element102. In an embodiment, the second parts of the multicarrier signals352,354,356are used as a low rate communication channel. Again it is reminded that two or more signals may be used. For example the second part of a FT DFT-s-OFDM signal may be used to map the ACK/NACK feedback for a Hybrid Automatic Repeat reRequest (HARQ) process. The same ACK/NACK message may be mapped over a set of time symbols, e.g. over an entire radio frame and/or a sub-frame. The set of time symbols may mean that each time symbol is represented by a FT DFT-s-OFDM signal. Using such approach may correspond to a repetition coding of the control message (e.g. ACK/NACK) which may allow obtaining combining gain at the receiver.

Repeating the control message for duration of two or more time symbols may also be beneficial in that the receiver may more reliably receive the transmitted control message. For example, if the control message would only be sent once, the receiving may be more unreliable compared to a situation where the control message is transmitted two or more times.

In an embodiment, the control message is divided between at least two multicarrier signals. For example, the first part of the first multicarrier signal352may comprise a first part of the control message, whereas the first part of the second multicarrier signal354may comprise a second part of the control message. The second parts of the first and second multicarrier signals352,354may comprise a third part of the control message. As said the second parts may comprise the same data and/or be substantially identical.

FIGS. 4A to 4Billustrate some embodiments. Although inFIGS. 4A to 4Bthe first terminal device110, or some other terminal device, is shown to be transmitting the described multicarrier signals, it may be equally possible that the multicarrier signals are transmitted by the network element102. Thus, it may be possible to use the described solution for uplink and/or downlink direction. In an embodiment, the apparatus performing the generation of the signals410and/or transmission of the signals comprises the first terminal device110, a part of the terminal device110(i.e. communication circuitry), the network element102, and/or a part of the network element102. The first terminal device110and/or the network element102may be comprised in a cellular network, such as the radio communication system described above.

Referring toFIG. 4A, the first terminal device110may transmit a first multicarrier signal410and a second multicarrier signal420to the network element102. The first and second signals410,420may be similar and/or the same multicarrier signals as described in relation toFIGS. 1 to 3C, for example.

In the example ofFIG. 4A, the first terminal device110may transmit the first and second multicarrier signals410,420simultaneously to the network element102. This may be achieved, for example, if the transmitted and the receiver are MIMO capable. In an embodiment, the first and second multicarrier signals410,420are transmitted substantially simultaneously in time domain.

In an embodiment, the first and second multicarrier signals410,420are transmitted using DC. For example, the network element102generates the signals410,420and transmits the first signal410to the first terminal device110, and causes another network element to transmit the second signal to the first terminal device110. The signals may be transmitted between the network elements using, for example, air interface and/or X2-interface. Naturally, it may be possible that only the data is transmitted between the network elements, and thus the signal generation is performed by the transmitting network element. The DC transmission may be coordinated, by the network element, so that the first and second multicarrier signals410,420are received substantially simultaneously by the first terminal device110. This may require, for example, changing Timing Advance (TA) value of the transmitting network element.

Referring toFIG. 4B, the transmitting of the first and second multicarrier signals410,420, by for example the first terminal device110or the network element102, may comprise broadcasting the second part414of the first multicarrier signal410and/or the second part424of the second multicarrier signal420. For example, the first terminal device110may broadcast the second part(s)414,424to a group of terminal devices402,404,406. This may be enabled by the D2D communication, for example. In an embodiment, the network element102broadcasts the second part(s)414,424to the group of terminal devices402,404,406. The group may normally comprise more than two or more terminal devices, but in special cases the group may comprise only one terminal device. In such case, the transmitting may be broadcasting if it is not directed to a single receiver. That is, the transmitting may not be unicasting.

Still referring toFIG. 4B, the first terminal device110may transmit the first part(s)412,414to the network element102. This may be performed together with the broadcasting of the second part(s)414,424. It needs to be further noted that although inFIG. 4Bthe first and second multicarrier signals are shown to be substantially simultaneous in time domain, it may be equally possible that they are transmitted and/or broadcasted one after the other (e.g. they are adjacent in time domain).

FIGS. 5A to 5Billustrate some embodiments.FIGS. 5A to 5Bmay illustrate embodiments that are usable in relation to the multicarrier signals introduced in relation toFIGS. 1 to 4B, for example. It needs to be noted that an update of the control message, such as a low rate communication channel message described above, may generate a non-cyclical ISI on a first symbol, or a first multicarrier signal, to which the new control message may be mapped. For example, if a first control message is transmitted over a first radio frame, and a second control message is transmitted over a second radio frame, meaning that multicarrier signals transmitted during the first radio frame may comprise the first control message, and multicarrier signals transmitted during the second radio frame may comprise the second control message, the transition between the two frames may cause the non-cyclical ISI on the first multicarrier signal of the second radio frame. To enhance delay spread control between changing second parts, the second part of the multicarrier signal may need to be manipulated.

Referring toFIG. 5A, a fixed part (also called as a second part)504,506of a multicarrier signal may be shown. The fixed part504,506may be similar or the same as the second part344shown inFIG. 3C, for example. As shown the fixed part502,504of the multicarrier signal may be generated so that the fixed part502,504comprises a first and second parts502,504, wherein the second part504comprises substantially zero values. This may allow to containing the energy components due the multipath propagation in the symbol itself, and thus reducing the impact of the energy spillover over the next symbol (or next multicarrier signal). In a way it may be understood that the length of the fixed part and/or the tail of the multicarrier signal is reduced by setting zero values at an end portion of the fixed part and/or the tail. As shown, a delay spread508may still be caused, but it may extend less over the next signal.

In an embodiment, a second data block, such as the second data block304, comprises a data part and a zero part, the zero part comprising at least one substantially zero value. For example, that the second parts of the first and second multicarrier signals352,354may be generated so that the zero part is subsequent in time domain compared with the data part. The effect of this may be shown inFIG. 5A, as also described above.

Referring toFIG. 5B, at least two multicarrier signals, such as the first and second multicarrier signals352,354, may be shown. A second part514of the first multicarrier signal352may be generated from the data of the second data block304, wherein a second part524,526of the second multicarrier signal354may be generated from at least one value of the second data block304and from at least one substantially zero value so that the at least one substantially zero value is subsequent in time domain compared with the at least one value of the second data block304. Thus, as shown inFIG. 5B, the second part524,526of the second multicarrier signal354may comprise the value part524and the zero part526.

Using this approach the interference to a consecutive signal, comprising a changed control message, may be reduced. This is due to that a second delay spread528may extend less over the next multicarrier signal compared to a first delay spread518extending over the second multicarrier signal. However, the second part524,526of the second multicarrier signal354may comprise at least most of the information comprised in the second part514of the first multicarrier signal352. In an embodiment, the second part524,526of the second multicarrier signal354and the second part514of the first multicarrier signal352differ from each other due to the introducing of the zero part526, wherein the zero part526may limit the data transmitted in the second part524,526of the second multicarrier signal354.

Still referring toFIG. 5B, it needs to be noted that the first parts512,522of the multicarrier signals352,354may comprise different data and/or may be generated from different data. As explained, the first part of the first multicarrier signal352may be generated based on one data block, whereas the first part of the second multicarrier signal354may be generated based on another data block.

FIG. 6illustrates a flow diagram according to an embodiment of the invention. Referring toFIG. 6, the network element102may transmit data to the first terminal device110(block602). The data may be any downlink data that is normally transmitted between the network and the user device, such as voice call data, SMS data, or mobile data, to name a few examples. It may also comprise configuration information, for example. The first terminal device110may receive the downlink data.

In block604, the first terminal device110may obtain and/or generate data that is to be transmitted to uplink direction (i.e. to the network element102). The data may comprise, for example, first, second and third data blocks described in relation toFIG. 2. In block606, the first terminal device110may continue on generating at least two multicarrier signals based on the data to be transmitted. For example, if there are two data blocks (i.e. first and third data blocks), the first terminal device110may generate two multicarrier signals.

The second data block obtained may comprise, for example, ACK and/or NACK message related to the data receiving in block602. That is, the first terminal device110may, for example, generate the data of the second data block based on the receiving of the data transmission (block602).

In block608, the first terminal device110may transmit the at least two multicarrier signals to the network element102. For example, if there are two multicarrier signals to be transmitted, wherein the signals comprise the first and third data blocks, the second parts (i.e. fixed parts or fixed tails) of the signals may be generated so that they comprise the ACK/NACK message to the data transmission of block602. Using such approach may help to handle the ISI, but may also save radio resources, as the ACK/NACK message may not need to be transmitted using a separate signal, and thus, time symbols may be saved.

FIG. 7provide apparatus700comprising a control circuitry (CTRL)710, such as at least one processor, and at least one memory730including a computer program code (software)732, wherein the at least one memory and the computer program code (software)732, are configured, with the at least one processor, to cause the respective apparatus700to carry out any one of the embodiments ofFIGS. 1 to 6, or operations thereof.

In an embodiment, these operations may comprise tasks, such as, obtaining, by an apparatus, a first data block, a second data block and a third data block; generating a first multicarrier signal, wherein a first part of the first multicarrier signal is generated based on a data of the first data block, and wherein a second part of the first multicarrier signal is generated based on a data of the second data block, the second part of the first multicarrier signal being subsequent in time domain compared with the first part of the first multicarrier signal; generating a second multicarrier signal, wherein a first part of the second multicarrier signal is generated based on a data of the third data block, and wherein a second part of the second multicarrier signal is generated based on the data of the second data block, the second part of the second multicarrier signal being subsequent in time domain compared with the first part of the second multicarrier signal; and transmitting the first and second multicarrier signals.

Referring toFIG. 7, the memory730may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The memory730may comprise a database734for storing data.

The apparatus700may further comprise radio interface (TRX)720comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The TRX may provide the apparatus with communication capabilities to access the radio access network and enable communication between network nodes, for example. In the case the apparatus700is the network element102, the TRX may provide the apparatus700connection to the above-mentioned X2 interface. The TRX may comprise standard well-known components such as an amplifier, filter, frequency-converter, (de)modulator, and encoder/decoder circuitries and one or more antennas.

The apparatus700may also comprise user interface740comprising, for example, at least one keypad, a microphone, a touch display, a display, a speaker, etc. The user interface740may be used to control the respective apparatus by a user of the apparatus700.

In an embodiment, the apparatus700may be or be comprised in a base station (also called a base transceiver station, a Node B, a radio network controller, or an evolved Node B, for example). In an embodiment, the apparatus700is or is comprised in the network element102.

In an embodiment, the apparatus700may be or be comprised in a terminal device, such as the first terminal device110or similar.

The control circuitry710may comprise a data obtainer circuitry712configured to obtaining a first data block, a second data block and a third data block. The control circuitry710may further comprise a signal generator circuitry714. The signal generator circuitry714may be configured to generate a first multicarrier signal, wherein a first part of the first multicarrier signal is generated based on a data of the first data block, and wherein a second part of the first multicarrier signal is generated based on a data of the second data block, the second part of the first multicarrier signal being subsequent in time domain compared with the first part of the first multicarrier signal. The signal generator circuitry714may be further configured to generate a second multicarrier signal, wherein a first part of the second multicarrier signal is generated based on a data of the third data block, and wherein a second part of the second multicarrier signal is generated based on the data of the second data block, the second part of the second multicarrier signal being subsequent in time domain compared with the first part of the second multicarrier signal. Further, the control circuitry710may comprise a signal transmitter circuitry716configured to transmit the first and second multicarrier signals. For example, the first terminal device110may transmit the first and second multicarrier signals to the network element102.

In an embodiment, as shown inFIG. 8, at least some of the functionalities of the apparatus700may be shared between two physically separate devices, forming one operational entity. Therefore, the apparatus700may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes. Thus, the apparatus700ofFIG. 7, utilizing such shared architecture, may comprise a remote control unit (RCU)852, such as a host computer or a server computer, operatively coupled (e.g. via a wireless or wired network) to a remote radio head (RRH)854located in the base station. In an embodiment, at least some of the described processes may be performed by the RCU852. In an embodiment, the execution of at least some of the described processes may be shared among the RRH854and the RCU852.

In an embodiment, the RCU852may generate a virtual network through which the RCU852communicates with the RRH854. 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 (i.e. to the RCU). 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 at least one terminal device110,120.

In an embodiment, at least some of the processes described in connection withFIGS. 1 to 6may be carried out by an apparatus comprising corresponding means for carrying out at least some of the described processes. Some example means for carrying out the processes may include at least one of the following: detector, processor (including dual-core and multiple-core processors), digital signal processor, controller, receiver, transmitter, encoder, decoder, memory, RAM, ROM, software, firmware, display, user interface, display circuitry, user interface circuitry, user interface software, display software, circuit, antenna, antenna circuitry, and circuitry. In an embodiment, the at least one processor, the memory, and the computer program code form processing means or comprises one or more computer program code portions for carrying out one or more operations according to any one of the embodiments ofFIGS. 1 to 6or operations thereof. In an embodiment, these operations may comprise tasks, such as, obtaining, by an apparatus, a first data block, a second data block and a third data block; generating a first multicarrier signal, wherein a first part of the first multicarrier signal is generated based on a data of the first data block, and wherein a second part of the first multicarrier signal is generated based on a data of the second data block, the second part of the first multicarrier signal being subsequent in time domain compared with the first part of the first multicarrier signal; generating a second multicarrier signal, wherein a first part of the second multicarrier signal is generated based on a data of the third data block, and wherein a second part of the second multicarrier signal is generated based on the data of the second data block, the second part of the second multicarrier signal being subsequent in time domain compared with the first part of the second multicarrier signal; and transmitting the first and second multicarrier signals.

According to yet another embodiment, the apparatus carrying out the embodiments comprises a circuitry including at least one processor and at least one memory including computer program code. When activated, the circuitry causes the apparatus to perform at least some of the functionalities according to any one of the embodiments ofFIGS. 1 to 6, or operations thereof. In an embodiment, these operations may comprise tasks, such as, obtaining, by an apparatus, a first data block, a second data block and a third data block; generating a first multicarrier signal, wherein a first part of the first multicarrier signal is generated based on a data of the first data block, and wherein a second part of the first multicarrier signal is generated based on a data of the second data block, the second part of the first multicarrier signal being subsequent in time domain compared with the first part of the first multicarrier signal; generating a second multicarrier signal, wherein a first part of the second multicarrier signal is generated based on a data of the third data block, and wherein a second part of the second multicarrier signal is generated based on the data of the second data block, the second part of the second multicarrier signal being subsequent in time domain compared with the first part of the second multicarrier signal; and transmitting the first and second multicarrier signals.