Signal phasing for transmissions in a communications network

Abstract

According to example aspects of the present disclosure, a method is provided that includes, for a sequence of binary data, generating a sequence of trellis coded modulation symbols in a complex quadrature phase shift keying, QPSK, constellation by means of a trellis code; generating a discrete Fourier transform, DFT, precoded orthogonal frequency-division multiplexing, OFDM, signal based on at least the sequence of trellis coded modulation symbols; and performing a transmission based on the generated DFT precoded OFDM signal, wherein a phase change between two consecutive trellis coded modulation symbols of the sequence is determined by the trellis code, and wherein an absolute difference between two phase changes determined consecutively by the trellis code is at most π / 2.

Description

Technical Field

[0001] Various example embodiments generally relate to communication networks, and more specifically to signal phase transitions for transmission in such networks. Background Technology

[0002] The signal phase transitions used for transmission can be used in various cellular communication networks, such as those operating under 5G radio access technology. 5G radio access technology can also be referred to as New Radio (NR) access technology. The 3rd Generation Partnership Project (3GPP) has developed standards for 5G / NR. Methods, apparatus, and computer programs related to enhancements in transmission within cellular communication networks are needed. Such enhancements may also be beneficial in other wireless communication networks, such as future 6G networks, or in any other suitable wireless communication network. Summary of the Invention

[0003] The subject matter of the independent claims is provided in several respects. Several example embodiments are defined in the dependent claims.

[0004] The scope of protection sought by the various exemplary embodiments of this disclosure is set forth in the independent claims. Exemplary embodiments and features (if any) described in this specification that do not fall within the scope of the independent claims are to be construed as examples useful for understanding the various exemplary embodiments of this disclosure.

[0005] According to a first aspect of this disclosure, an apparatus is provided, comprising at least one processor and at least one memory storing instructions, said instructions, when executed by the at least one processor, causing the apparatus to at least: generate a trellis-coded modulation symbol sequence in a complex quadrature phase shift keying (QPSK) constellation for a binary data sequence by means of trellis codes; generate a discrete Fourier transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signal based at least on the trellis-coded modulation symbol sequence; and perform transmission based on the generated DFT pre-coded OFDM signal, wherein a phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis codes, and wherein the absolute difference between two consecutive phase transitions determined by the trellis codes is at most π / 2.

[0006] Example embodiments of the apparatus according to the first aspect may include at least one feature from the following bullet point list or any combination of the following features: - Wherein the trellis code is a two-state recursive trellis code including a first state and a second state, wherein the phase transition used to generate the corresponding trellis codec modulation symbol when transitioning from the first state to the second state or from the second state to the first state is equal to 0, wherein the phase transition used to generate the corresponding trellis codec modulation symbol when transitioning from the first state back to the first state is equal to +π / 2, and wherein the phase transition used to generate the corresponding trellis codec modulation symbol when transitioning from the second state back to the second state is equal to -π / 2; - The apparatus is further configured to: determine a first phase transition of the first grid codec modulation symbol used to generate the sequence to be 0; and based on determining the first phase transition to be 0, determine a second phase transition of the second continuous grid codec modulation symbol used to generate the sequence to be -π / 2, 0, or +π / 2; - The apparatus is further configured to: determine that a first phase transition of the first grid-coded modulation symbol used to generate the sequence is -π / 2; and based on the determination that the first phase transition is -π / 2, determine that a second phase transition of the second continuous grid-coded modulation symbol used to generate the sequence is -π / 2 or 0; - The apparatus is further configured to: determine that a first phase transition of a first grid-coded modulation symbol for generating a sequence is +π / 2; and based on the determination that the first phase transition is +π / 2, determine that a second phase transition of a second continuous grid-coded modulation symbol for generating a sequence is +π / 2 or 0; - The apparatus is further configured to: insert additional modulation symbols interleaved with the lattice-coded modulation symbol sequence, wherein the interleaved modulation symbols have the same amplitude as the previous and consecutive lattice-coded modulation symbols, and phase interpolated from the phase of the previous and consecutive lattice-coded modulation symbols; and generate a DFT pre-coded OFDM signal based at least on the lattice-coded modulation symbol sequence and the interleaved modulation symbols; - The apparatus is further configured to generate a DFT pre-coded OFDM signal by truncating the DFT domain sequence to a preferred bandwidth of size M+E DFT bins for input to the inverse fast Fourier transform (IFFT), where M represents the length of the sequence and E represents a positive integer, where 0 ≤ E ≤ M. - in M+E Each DFT frequency grid is centered around the DC frequency grid of the DFT domain sequence; - The device is further configured to: determine whether the size of the allocation transmitted in the frequency domain is lower than a threshold; and when the size of the allocation transmitted is lower than or equal to the threshold, perform an insertion; - The device is further configured to: determine whether the size of the allocation transmitted in the frequency domain is lower than a threshold; and consider the allocation invalid when the size of the allocation transmitted is higher than the threshold; - Where the threshold is half of the maximum allocation size transmitted in the frequency domain; - The device is further configured such that: one bit of each binary data sequence generates a trellis-coded modulation symbol for a trellis-coded modulation symbol sequence.

[0007] According to a second aspect of this disclosure, an apparatus is provided, comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the at least one processor, causing the apparatus to at least: receive a Discrete Fourier Transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signal; determine a trellis-coded modulation symbol sequence from the DFT pre-coded OFDM signal; and determine a binary data sequence from the trellis-coded modulation symbol sequence and based on a trellis code used to generate the trellis-coded modulation symbol sequence, wherein a phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

[0008] Example embodiments of the apparatus according to the second aspect may include at least one feature from the following bullet point list or any combination of the following features: - Wherein the trellis code is a two-state recursive trellis code including a first state and a second state, wherein the phase transition used to decode the corresponding trellis codec modulation symbol when transitioning from the first state to the second state or from the second state to the first state is equal to 0, wherein the phase transition used to decode the corresponding trellis codec modulation symbol when transitioning from the first state back to the first state is equal to +π / 2, and wherein the phase transition used to decode the corresponding trellis codec modulation symbol when transitioning from the second state back to the second state is equal to -π / 2; - The apparatus is further configured to: determine a first phase transition of 0 for a first grid codec modulation symbol for a decoded sequence; and based on determining the first phase transition of 0, determine a second phase transition of -π / 2, 0, or +π / 2 for a second consecutive grid codec modulation symbol for a decoded sequence; - The apparatus is further configured to: determine that a first phase transition of a first grid-coded modulation symbol for a decoded sequence is -π / 2; and based on the determination that the first phase transition is -π / 2, determine that a second phase transition of a second consecutive grid-coded modulation symbol for a decoded sequence is -π / 2 or 0; - The apparatus is further configured to: determine that a first phase transition of a first grid-coded modulation symbol for a decoding sequence is +π / 2; and based on the determination that the first phase transition is +π / 2, determine that a second phase transition of a second continuous grid-coded modulation symbol for a decoding sequence is +π / 2 or 0.

[0009] According to a third aspect of this disclosure, a first method is provided, comprising: generating a trellis-coded modulation symbol sequence in a complex quadrature phase shift keying (QPSK) constellation for a binary data sequence by means of trellis codes; generating a discrete Fourier transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signal based at least on the trellis-coded modulation symbol sequence; and performing transmission based on the generated DFT pre-coded OFDM signal, wherein a phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis codes, and wherein the absolute difference between two consecutively determined phase transitions by the trellis codes is at most π / 2.

[0010] An example embodiment of the first method according to the third aspect corresponds to an example embodiment of the apparatus according to the first aspect.

[0011] According to a fourth aspect of this disclosure, a second method is provided, comprising: receiving a Discrete Fourier Transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signal; determining a trellis-coded modulation symbol sequence from the DFT pre-coded OFDM signal; and determining a binary data sequence from the trellis-coded modulation symbol sequence and based on a trellis code used to generate the trellis-coded modulation symbol sequence, wherein a phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

[0012] An example embodiment of the second method according to the fourth aspect corresponds to an example embodiment of the apparatus according to the second aspect.

[0013] According to a fifth aspect of this disclosure, an apparatus is provided, comprising: means for generating a trellis-coded modulation symbol sequence for a binary data sequence in a complex quadrature phase shift keying (QPSK) constellation by means of trellis codes; means for generating a discrete Fourier transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signal based at least on the trellis-coded modulation symbol sequence; and means for performing transmission based on the generated DFT pre-coded OFDM signal, wherein a phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis codes, and wherein the absolute difference between two consecutive phase transitions determined by the trellis codes is at most π / 2.

[0014] Example embodiments of the apparatus according to the fifth aspect correspond to example embodiments of the apparatus according to the first aspect.

[0015] According to a sixth aspect of this disclosure, an apparatus is provided, comprising: means for receiving a Discrete Fourier Transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signal; means for determining a trellis-coded modulation symbol sequence from the DFT pre-coded OFDM signal; and means for determining a binary data sequence from the trellis-coded modulation symbol sequence and based on a trellis code for generating the trellis-coded modulation symbol sequence, wherein a phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

[0016] An example embodiment of the apparatus according to the sixth aspect corresponds to an example embodiment of the apparatus according to the second aspect.

[0017] According to a seventh aspect of this disclosure, a non-transitory computer-readable medium is provided having a computer-readable instruction set stored thereon, which, when executed by at least one processor, causes a device to perform at least the first method according to the third aspect or the second method according to the fourth aspect.

[0018] According to an eighth aspect of this disclosure, a computer program including instructions is provided, which, when executed by a device, cause the device to perform a first method according to a third aspect or a second method according to a fourth aspect. Attached Figure Description

[0019] Figure 1 Examples of network scenarios according to at least some example embodiments are shown; Figure 2a A first example of bit mapping and phase transition according to at least some example embodiments is shown; Figure 2b A second example of bit mapping and phase transition according to at least some example embodiments is shown; Figure 3a Examples of the operation of a transmitter according to at least some example embodiments are shown; Figure 3b Examples of the operation of the receiver according to at least some example embodiments are shown; Figure 4 An example apparatus capable of supporting at least some of the example embodiments is shown; Figure 5 A flowchart of a first method according to at least some example embodiments is shown; and Figure 6 A flowchart of a second method according to at least some example embodiments is shown. Detailed Implementation

[0020] Embodiments of this disclosure provide improvements to signal phase transitions for transmission in cellular communication networks. More specifically, embodiments of this disclosure achieve low peak-to-average power ratio (PAPR) transmission in such networks.

[0021] Figure 1 Examples of network scenarios according to at least some example embodiments are shown. Figure 1 In an example scenario, a communication system may exist, comprising a user equipment (UE) 110, a wireless network node 120, and core network elements 130. The UE 110 may connect to the wireless network node 120 via an air interface 115. The UE 110 may connect to the wireless network node 120, for example, by using multiple beams simultaneously or one at a time. That is, the air interface 115 may be a beam-based air interface.

[0022] UE 110 may include, for example, a smartphone, cellular phone, machine-to-machine (M2M) node, machine-type communication (MTC) node, Internet of Things (IoT) node, automotive telemetry unit, laptop computer, tablet computer, or virtually any suitable wireless terminal. Wireless network node 120 may be considered a serving node of UE 110, and a cell of wireless network node 120 may be a serving cell of UE 110. At least some example embodiments of this disclosure can be applied in the context of low-power wide-area (LPWA).

[0023] The air interface between UE 110 and wireless network node 120 can be configured according to the fact that both UE 110 and wireless network node 120 are configured to support a Radio Access Technology (RAT). Examples of cellular RATs include Long Term Evolution (LTE), New Radio (NR), which can also be referred to as 5G, Radio Access Technology, and MulteFire. Future 6G can also be an example of a cellular RAT.

[0024] For example, in the context of LTE, Radio Network Node 120 may be referred to as an eNB, while in the context of NR, Radio Network Node 120 may be referred to as a gNB. In some example embodiments, Radio Network Node 120 may be referred to as a Transceiver Point (TRP), or multiple TRPs that can be co-located or non-co-located. In any case, the example embodiments of this disclosure are not limited to any particular wireless technology. Rather, the example embodiments can be utilized in any wireless communication system where phase transitions for transmission are used.

[0025] Wireless network node 120 can connect to core network 130 directly or via at least one intermediate node through interface 125. Core network 130 can also connect to another network (…) via interface 135. Figure 1(Not shown in the image) Coupled, the other network can provide access to other networks, for example, via a global interconnection network. The wireless network node 120 can be connected directly to the core network 130 or another core network, or via at least one intermediate node.

[0026] In some example embodiments, the network scenario may include a relay node in place of or in addition to UE 110 and / or radio network node 120. For example, a relay may be used when operating on millimeter-wave frequencies. One example of a relay node may be an Integrated Access and Backhaul (IAB) node. An IAB node may also be referred to as a self-backhaul relay. Another example of a relay may be an out-of-band relay. Typically, a relay node may include two parts: - The Distributed Unit (DU) portion can facilitate the functionality of the wireless network node 120 (such as a gNB). Therefore, in some example embodiments, the relayed DU portion may be referred to as the wireless network node 120, and the DU can perform the tasks of the wireless network node 120; - The mobile terminal MT portion can facilitate the functionality of UE 110, namely, the backhaul link, which can be a communication link between a parent node (DU) (such as the DU portion of wireless network node 120) and a relay (such as an IAB node). In some example embodiments, the MT portion may be referred to as UE 110 and perform the tasks of UE 110.

[0027] At least some exemplary embodiments of this disclosure can be described using NR specifications and terminology. However, it should be noted that the same radio frequency (RF) limitations may be faced, at least in 6G. Therefore, the exemplary embodiments of this disclosure can be similarly applied to 6G or any other similar systems in the future.

[0028] Using NR as an example, at least in the downlink, at least one modulation method can be used, such as Quadrature Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (QAM), 64QAM, and even up to 1024 QAM. However, uplink coverage is a particularly important issue. As an example, at least two waveforms can be supported for the uplink, such as Orthogonal Frequency Division Multiplexing (OFDM) and Discrete Fourier Transform Extended OFDM (DFT-s-OFDM). DFT-s-OFDM can be used to significantly reduce PAPR, thus enabling better coverage. Furthermore, in the uplink, π / 2 Binary Phase Shift Keying (BPSK) can be configured, and frequency domain spectral shaping (FDSS) can be used to achieve very low PAPR. In addition, FDSS can be used with and without spectral extension, where spectral extension can be utilized to increase coverage, for example, for π / 2 BPSK or QPSK modulation.

[0029] In the future, at least in 6G, additional coverage solutions may be needed. These additional coverage solutions could be beneficial, at least for enhanced mobile broadband (eMBB) (e.g., when operating in the 6-15 GHz frequency range) and for various LPWA use cases.

[0030] Furthermore, π / 2 BPSK with FDSS can provide a low PAPR, for example, a 3dB PAPR reduction at the 1% complementary cumulative distribution function (CCDF) point compared to QPSK. Therefore, a reduced MPR (i.e., higher radiated power) can be achieved at UE 110. However, even a lower PAPR might be desirable. Even with modulation methods with constant amplitude symbols (such as BPSK), the amplitude of the generated waveform can vary significantly, and abrupt phase transitions may occur between consecutive symbols and / or samples. Furthermore, phase discontinuities may arise due to the cyclic prefix CP, and have an impact on the waveform's PAPR and out-of-band (OOB) characteristics. Therefore, a modulation method that minimizes both PAPR and OOB is needed, as the waveform's PAPR and spectrum play a crucial role in waveform coverage. At least in some scenarios, a lower PAPR can also reduce the power consumption of UE 110. A smaller PAPR can also help reduce the cost (complexity) of the UE 110 transmitter. The modulation method disclosed herein can be used by any wireless transmitter (such as UE 110 or wireless network node 120).

[0031] Out-of-band (OOB) transmissions (e.g., Adjacent Channel Leakage Ratio (ACLR) or spectrum emission masking) can very quickly limit the coverage area of ​​UE 110 when the allocation is not in the center of the operating band or when the allocation is large compared to the bandwidth of the operating band. In some example embodiments, the allocation of the above 50 resource blocks can be considered large. For example, assuming a channel bandwidth of 20 MHz and a subcarrier spacing of 15 kHz, the total number of resource blocks could be 100. In this case, UE 110 may need and be allowed to apply a large Maximum Power Reduction (MPR) to meet OOB transmission limits. It is also evident from the specifications that MPR requirements have been defined differently for different allocation areas, as shown in, for example, Table 1.

[0032] Table 1 Maximum Power Reduction (MPR) for Power Level 3

[0033] Even without any shaping, QPSK and π / 2 BPSK for DFT-s-OFDM may be constrained by ACLR or spectral transmit mask SEM for edge allocations, and even for internal allocations if the allocation size is large enough. Similarly, for external allocations (which can be between internal and edge allocations), QPSK and π / 2 BPSK for DFT-s-OFDM can be ACLR or SEM-constrained. Depending on the scenario, there may also be other resource block regions with associated MPR and / or other maximum / minimum transmit power related requirements.

[0034] Therefore, at least some example embodiments of this disclosure provide an implementation for trellis coding to transmit binary data sequences using symbols of a QPSK constellation. Trellis coding can be used to avoid abrupt phase transitions in the generated symbol sequence. The generated symbol sequence can cover the entire transmission. Alternatively or additionally, phase interpolation can be applied to the trellis-coded signal, instead of linear FDSS, to generate an oversampled signal with reduced amplitude and phase changes.

[0035] In some example embodiments, trellis coding and phase interpolation can be used together to significantly reduce out-of-band (OOB) transmissions and phase-reactive propagation (PAPR) of the transmitted signal. These advantages can be achieved without bandwidth extension (i.e., transmitting M bits using M subcarriers in a DFT-s-OFDM signal). However, in some example embodiments, bandwidth extension can be applied to further enhance these advantages. Furthermore, the use of trellis coding enables the use of efficient sequence detection methods, such as the Soft Output Viterbi (SOVA) algorithm or the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm, for soft detection of transmitted symbol sequences. Using such efficient detection methods can improve link performance.

[0036] In some example embodiments, both OOB and PAPR can be improved if abrupt phase transitions (continuous +π / 2 and -π / 2) are avoided by using a two-state trellis code as follows: - After phase transition 0, phase transitions of -π / 2 and +π / 2 are allowed; - After the phase transition -π / 2, phase transitions of -π / 2 and 0 are allowed; and - After the phase transition +π / 2, phase transitions +π / 2 and 0 are allowed.

[0037] Therefore, a wireless transmitter, such as UE 110 or wireless network node 120, can generate a trellis-coded modulation symbol sequence in a complex QPSK constellation using trellis codes for a binary data sequence. The wireless transmitter can then generate a DFT-precoded OFDM signal based at least on the trellis-coded modulation symbol sequence. The wireless transmitter can then perform transmission based on the generated DFT-precoded OFDM signal, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code (and is equal to 0, +π / 2, or -π / 2), and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

[0038] In some example embodiments, bit rates higher than 1 bit per modulation symbol may be considered. However, the example embodiments of this disclosure may be particularly advantageous for the case of 1 bit per symbol. For example, if the goal is to achieve a π / 2 BPSK data rate with significantly improved PAPR and OOB, the case of 1 bit per symbol may be particularly beneficial for 6G.

[0039] Figure 2a A first example of bit mapping and phase transition according to at least some example embodiments is shown. Figure 2b A second example of bit mapping and phase transition according to at least some example embodiments is shown. More specifically, Figure 2a and Figure 2b Bit mappings and phase transition diagrams for two alternative recursive lattice encoding / decoding processes are shown. Figure 2a and Figure 2b In the middle, b and These indicate that the current binary value being encoded is equal to the previously encoded binary value or its complement. The first state of the lattice encoding / decoding process is represented by "+", and the second state is represented by "-". That is, Figure 2a and Figure 2b The lattice code is shown, which is a two-state recursive lattice code comprising first states 202 and 212 and second states 204 and 214 respectively. Wireless transmitters (such as...) Figure 1 The UE110 or wireless network node120 can generate a grid-coded modulation symbol in a grid-coded modulation symbol sequence for each bit of the binary data sequence.

[0040] Figure 2aA first-state trellis diagram is depicted for generating a trellis-encoded modulation symbol sequence from a binary data sequence. Complex modulation symbols are selected from a complex constellation of {1, j, -1, -j}. The trellis encoder is initialized in the first state 202, and the binary value '1' and the complex modulation symbol '1' are assumed to be the starting values ​​(other initialization choices are possible). The transmitter can determine the phase transition of the continuous trellis-encoded modulation symbols as follows: If the first binary value in the binary data sequence to be decoded is '1', i.e., the same value as the initial binary value (b), then the phase transition can be '+π / 2', corresponding to the complex modulation symbol 'j' (if starting from the complex modulation symbol '1', and the positive angle is counterclockwise), and the transmitter can remain in the first state 202. Otherwise, if the first binary value in the binary data sequence to be encoded is '0', i.e., a value different from the initial binary value (b), then the phase transition can be '+π / 2', corresponding to the complex modulation symbol 'j' (if starting from the complex modulation symbol '1', and the positive angle is counterclockwise), and the transmitter can remain in the first state 202. If the phase transition is '0', corresponding to the same modulation symbol '1', then the transmitter can move to the second state 204. Therefore, the phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning from the first state 202 to the second state 204 can be equal to 0. When transitioning back from the first state 202 to the first state 202 (or equivalently when remaining in the first state 202), the phase transition used to generate the corresponding trellis-coded modulation symbol can be equal to +π / 2.

[0041] Assuming the previous binary value '0' was encoded as the complex modulation symbol '1', and assuming the transmitter is in state 204, if the next binary value in the binary data sequence to be encoded is '1', i.e., a value different from the previous binary value ( If the next binary value in the binary data sequence to be encoded is '0', which is the same value as the previous binary value (b), then the phase transition can be '0', which corresponds to the complex modulation symbol '1', and the transmitter can move to the first state 202. Therefore, the phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning from the second state 204 to the first state 202 can be equal to 0. The phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning back from the second state 204 to the second state 204 (or equivalently while remaining in the second state 204) can be equal to -π / 2. From the first state 202, the operation of the transmitter can continue again by determining the phase transition of the next trellis-coded modulation symbol as described above.

[0042] Figure 2bA second-state trellis diagram is depicted for generating a trellis-encoded modulation symbol sequence from a binary data sequence. The complex modulation symbols are again selected from a complex constellation of {1, j, -1, -j}. The trellis encoder is initialized in the first state 212, and the binary value '1' and the complex modulation symbol '1' are assumed as initial values ​​(other initialization choices are possible). The transmitter can determine the phase transition of the continuous trellis-encoded modulation symbols as follows: If the first binary value in the binary data sequence to be encoded is '0', i.e., a value different from the initial binary value (… If the first binary value in the binary data sequence to be encoded is '1', i.e., the same value as the initial binary value (b), then the phase transition can be '0', corresponding to the same modulation symbol '1', and the transmitter can move to the second state 214. Therefore, the phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning from the first state 212 to the second state 214 can be equal to 0. The phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning back from the first state 212 (or equivalently, when remaining in the first state 212) can be equal to +π / 2.

[0043] Assuming the previous binary value '1' was encoded as modulation symbol '1', and assuming the transmitter is in state 214, if the next binary value in the binary data sequence to be encoded is '1', i.e., the same value as the previous binary value (b), then the phase transition could be '-π / 2', corresponding to the complex modulation symbol '-j', and the transmitter could remain in state 214. Otherwise, if the next binary value in the binary data sequence to be encoded is '0', i.e., a value different from the previous binary value (b), then the phase transition could be '-π / 2', corresponding to the complex modulation symbol '-j', and the transmitter could remain in state 214. If the phase transition is '0', corresponding to the complex modulation symbol '1', the transmitter can move to the first state 212. Therefore, the phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning from the second state 214 to the first state 212 can be equal to 0. The phase transition used to generate the corresponding trellis-coded modulation symbol when transitioning back from the second state 214 (or equivalently while remaining in the second state 214) can be equal to -π / 2. From the first state 212, the operation of the transmitter can continue again by determining the phase transition of the next trellis-coded modulation symbol as described above.

[0044] In some example embodiments, the wireless transmitter may determine that the first phase transition of the first lattice-coded modulation symbol used to generate the sequence is 0. In this case, the wireless transmitter may determine the second phase transition of the second consecutive lattice-coded modulation symbol used to generate the sequence to be -π / 2, 0, or +π / 2 based on determining that the first phase transition is 0.

[0045] In some example embodiments, the wireless transmitter may determine that the first phase transition of the first lattice-coded modulation symbol used to generate the sequence is -π / 2 (in the second states 204, 214). In this case, the wireless transmitter may determine, based on the determination that the first phase transition is -π / 2, that the second phase transition of the second consecutive lattice-coded modulation symbol used to generate the sequence is either -π / 2 or 0 (to remain in the second states 204, 214 or move to the first states 202, 212).

[0046] In some example embodiments, the wireless transmitter may determine that the first phase transition of the first lattice-coded modulation symbol used to generate the sequence is +π / 2 (in the first states 202, 212). In this case, the wireless transmitter may determine, based on the determination that the first phase transition is +π / 2, that the second phase transition of the second consecutive lattice-coded modulation symbol used to generate the sequence is either +π / 2 or 0 (to remain in the first states 202, 212 or move to the second states 204, 214).

[0047] Therefore, there can exist a state: "+" (first state 202, 212), from which the next phase transition is... / 2 or 0, and a state "-" (second state 204, 214), from which the phase transition is / 2 or 0. The purpose of bit mapping can be to minimize the Hamming distance of a sequence with a small Euclidean distance. As an example, the binary data sequence {1 1 0 0 10} can correspond to the phase transition sequence {π / 2, π / 2, 0, 0, -π / 2}, for example, assuming the encoding / decoding process starts with the state '+' and the binary value '1'. After trellis encoding / decoding, and assuming the initial complex modulation symbol is '1', the sequence can be represented as the complex QPSK symbol sequence {j, -1, -1, -1, -1, j}.

[0048] In some example embodiments, it is possible to obtain from Choose complex modulation symbols from complex constellations instead of the complex constellation {1,j,-1,-j}.

[0049] In some example embodiments, consider Figure 2a and Figure 2b The phase transition diagram can have four alternative bit mappings. However, Figure 2a and Figure 2b The two additional bit mappings not shown in the diagram may result in significantly worse link performance.

[0050] Figure 3a An example of the operation of a transmitter according to at least some example embodiments is shown. Figure 3b Examples of receiver operation according to at least some example embodiments are shown. Therefore, Figure 3a and Figure 3bThe entire transmission scheme is shown together, including baseband transmitter and receiver signal processing, but excluding error control codec elements. Figure 3a The wireless transmitter can be UE 110 or wireless network node 120, and Figure 3b The wireless receiver can be either wireless network node 120 or UE 110.

[0051] Reference Figure 3a In step 302, the transmitter can determine the bit source. In step 304, the transmitter can, for example, based on... Figure 2a or Figure 2b Mesh coding / decoding is performed on the QPSK constellation. In step 306, the transmitter can perform a 2x oversampling via phase interpolation. Therefore, after mesh coding / decoding, the transmitter can oversample the signal by a factor of two using phase interpolation. Phase interpolation is accomplished by inserting new additional modulation symbols interleaved with the mesh-coded modulation symbol sequence. The interleaved modulation symbols can have the same amplitude as the previous and consecutive mesh-coded modulation symbols, and the phase interpolated from the previous and consecutive mesh-coded modulation symbols. This phase interpolation may not be a linear filtering process, but it can significantly reduce PAPR and OOB transmissions compared to linear FDSS.

[0052] After phase interpolation, for example, the bit sequence {1 1 0 0 1 0} can appear as the complex symbol sequence {j, (-1+j) / √2, -1, -1, -1, -1, -1, -1, -1, (-1+j) / √2, j}. Additionally, cyclic expansion (i.e., interpolation between the first and last input samples) can be used to obtain a 2x oversampled sequence of length 2M. Continuing with the previous example, the resulting complex symbol sequence of length 12 is {j, (-1+j) / √2, -1, -1, -1, -1, -1, -1, -1, (-1+j) / √2, j, j}.

[0053] In step 308, the transmitter can perform DFT processing. A DFT can be performed on the oversampled symbol sequence, where the bandwidth of the oversampled symbol sequence can be twice the bandwidth of the initial symbol sequence.

[0054] At step 310, the transmitter may perform subcarrier mapping using spectral truncation or FDSS shaping (if any). FDSS may be applied to the oversampled DFT sequence. However, in some example embodiments, the DFT-domain sequence may be truncated to a preferred bandwidth by mapping M+E DFT bins, which may be centered on the DC bin of the DFT-domain sequence. For example, M bins may follow the existing frequency-domain resource allocation (received by UE 110 from the radio network node 120), and bandwidth expansion may be performed by reserving E / 2 bins on both sides of the M bins. In some example embodiments, M may be the number of bits mapped to a DFT-s-OFDM symbol (i.e., also representing the length of the modulated symbol sequence before oversampling), and E may correspond to the excess band size (if any). The zero excess band case (E = 0) may be preferred, but increasing the excess band (0 < E ≤ M) provides lower PAPR and lower OOB emissions. Thus, E may be a positive integer where 0 ≤ E ≤ M.

[0055] At step 312, the transmitter may perform IFFT processing. At step 314, the transmitter may perform CP insertion. The signal may be transmitted after this step. Thus, the transmitter may perform transmission based on the generated DFT precoded OFDM signal, where the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and where the absolute difference between two phase transitions consecutively determined by the trellis code is at most π / 2.

[0056] In some example embodiments, the transmitter may generate a DFT precoded OFDM signal based at least on the sequence of trellis-coded modulation symbols inserted at step 306 and the interleaved modulation symbols.

[0057] Referring to Figure 3b In step 322, the receiver may receive the DFT precoded signal and perform CP removal. In step 324, the receiver may perform FFT processing. In step 326, the receiver may perform filtering and channel equalization through a weight mask. In step 328, the receiver may perform IFFT. In step 330, the receiver may perform detection, i.e., determine the trellis-coded modulation symbol sequence from the DFT precoded OFDM signal, and determine the binary data sequence from the trellis-coded modulation symbol sequence and based on the trellis code used to generate the trellis-coded modulation symbol sequence, where the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and where the absolute difference between two phase transitions consecutively determined by the trellis code is at most π / 2.

[0058] In some example embodiments, the transmitter can determine whether the size of the transmission allocation in the frequency domain is below a threshold. When the size of the transmission allocation is below or equal to the threshold, the transmitter can perform the insertion of additional modulation symbols interleaved with the trellis-coded modulation symbol sequence, wherein the interleaved modulation symbols have the same amplitude as the previous and consecutive trellis-coded modulation symbols, and the phase interpolated from the phase of the previous and consecutive trellis-coded modulation symbols. The transmitter can then generate a DFT-pre-coded OFDM signal based at least on the trellis-coded modulation symbol sequence and the interleaved modulation symbols. Alternatively, when the size of the transmission allocation is above the threshold, the transmitter can consider the allocation invalid.

[0059] For example, the insertion of interleaved modulation symbols can be limited to the allocation size. 0.5* (PRB), where the nominal size ( It can be one of the following: - For example, the maximum bandwidth portion size defined in the 3GPP standard specification (e.g., 275 RBs in NR); or - The maximum allocation size that UE 110 can apply to other uplink transmission schemes, such as DFT-s-OFDM without mesh coding.

[0060] Therefore, the threshold for inserting interleaved modulation symbols can be half the maximum allocation size transmitted in the frequency domain, such as the maximum bandwidth portion size or the applicable maximum allocation size.

[0061] In some example embodiments, the maximum allocation size obtained ( It may be necessary to follow existing DFT size rules; for example, the number of PRBs can be implemented as follows: Where a, b, and c can be integers. Therefore, a DFT size that may already exist in the implementation can be used. In this case, no additional hardware will be required.

[0062] Figure 4An example apparatus capable of supporting at least some of the example embodiments is shown. A device 400 is shown, which may include, for example, a UE 110 or a wireless network node 120, or a control device configured to potentially control its functionality when installed therein. Device 400 includes a processor 410, which may include, for example, a single-core or multi-core processor, wherein the single-core processor includes one processing core, and the multi-core processor includes more than one processing core. Processor 410 typically includes a control device. Processor 410 may include more than one processor. Processor 410 may be a control device. Processing cores may include, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core manufactured by Advanced Micro Devices Corporation. Processor 410 may include at least one Qualcomm Snapdragon and / or Intel Atom processor. Processor 410 may include at least one application-specific integrated circuit (ASIC). Processor 410 may include at least one field-programmable gate array (FPGA). Processor 410 may be a component for performing method steps in device 400. Processor 410 may be configured at least partially by computer instructions to perform actions.

[0063] A processor may include, or be configured as, one or more circuits configured to perform stages of the methods according to the example embodiments described herein. As used herein, the term “circuit” may refer to one or more of the following: (a) a hardware-only circuit implementation, such as an implementation in analog and / or digital circuits only; and (b) a combination of hardware circuitry and software, such as, if applicable: (i) a combination of analog and / or digital hardware circuitry with software / firmware; and (ii) any portion of a hardware processor having software (including digital signal processors, software, and memory that work together to enable a device such as a mobile phone or server to perform various functions); and (c) hardware circuitry and / or processors that require software (e.g., firmware) to operate, such as a microprocessor or a portion thereof, but where the software may not be present when it is not required to operate.

[0064] This definition of "circuit" applies to all uses of the term in this application (including in any claim). As another example, as used in this application, the term "circuit" also covers implementations of hardware circuitry or processors (or processors in general) and their accompanying software and / or firmware. The term "circuit" also covers, for example and if applicable to a particular claim element, baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or network devices.

[0065] Device 400 may include memory 420. Memory 420 may include random access memory and / or permanent memory. Memory 420 may include at least one RAM chip. For example, memory 420 may include solid-state, magnetic, optical, and / or holographic memory. Memory 420 may be at least partially accessible by processor 410. Memory 420 may be at least partially included in processor 410. Memory 420 may be a means for storing information. Memory 420 may include computer instructions configured to be executed by processor 410. When computer instructions configured to cause processor 410 to perform certain actions are stored in memory 420, and device 400 as a whole is configured to operate under the guidance of processor 410 using computer instructions from memory 420, processor 410 and / or at least one of its processing cores may be considered to be configured to perform said certain actions. Memory 420 may be at least partially included in processor 410. Memory 420 may be at least partially external to device 400, but accessible by device 400.

[0066] Device 400 may include a transmitter 430. Device 400 may include a receiver 440. Transmitter 430 and receiver 440 may be configured to transmit and receive information according to at least one cellular or non-cellular standard. Transmitter 430 may include more than one transmitter. Receiver 440 may include more than one receiver. For example, transmitter 430 and / or receiver 440 may be configured to operate according to Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), and / or 5G / NR standards.

[0067] Device 400 may include a near-field communication (NFC) transceiver 450. The NFC transceiver 450 may support at least one NFC technology, such as Bluetooth, Wibree, or similar technologies.

[0068] Device 400 may include a user interface (UI) 460. UI 460 may include at least one of a display, keyboard, touchscreen, vibrator arranged to signal to the user by causing device 400 to vibrate, speaker, and microphone. The user may be able to operate device 400 via UI 460, for example, to accept incoming telephone calls, initiate telephone or video calls, browse the internet, manage digital files stored in memory 420 or accessible in the cloud via transmitter 430 and receiver 440 or via NFC transceiver 450, and / or play games.

[0069] Device 400 may include or be arranged to accept a user identity module 470. User identity module 470 may include, for example, a subscriber identity module SIM card that can be installed in device 400. User identity module 470 may include subscription information identifying the user of device 400. User identity module 470 may include password information that can be used to verify the identity of the user of device 400 and / or facilitate the encryption of transmitted information and billing of the user of device 400 for communications performed via device 400.

[0070] Processor 410 may be equipped with a transmitter arranged to output information from processor 410 to other devices included in device 400 via electrical leads within device 400. Such a transmitter may include a serial bus transmitter arranged to output information to memory 420 for storage, for example, via at least one electrical lead. Alternatively, the transmitter may include a parallel bus transmitter. Similarly, processor 410 may include a receiver arranged to receive information from other devices included in device 400 via electrical leads within device 400. Such a receiver may include a serial bus receiver arranged to receive information from receiver 440, for example, via at least one electrical lead, for processing within processor 410. Alternatively, the receiver may include a parallel bus receiver.

[0071] Device 400 may include Figure 4 Other devices not shown. For example, in the case where device 400 includes a smartphone, it may include at least one digital camera. Some devices 400 may include a rear camera and a front camera, wherein the rear camera may be designed for digital photography and the front camera for video calling. Device 400 may include a fingerprint sensor arranged to at least partially authenticate the user of device 400. In some example embodiments, device 400 lacks at least one of the above-mentioned devices. For example, some devices 400 may lack an NFC transceiver 450 and / or a user identity module 470.

[0072] Processor 410, memory 420, transmitter 430, receiver 440, NFC transceiver 450, UI 460, and / or user identity module 470 can be interconnected in various ways via electrical leads within device 400. For example, each of the aforementioned devices can be individually connected to the main bus within device 400 to allow the devices to exchange information. However, as those skilled in the art will understand, this is merely an example, and various ways of interconnecting at least two of the aforementioned devices may be chosen depending on the exemplary embodiment without departing from the scope of the exemplary embodiment.

[0073] Figure 5This is a flowchart of a first method according to at least some example embodiments. The steps of the first method can be performed by any wireless transmitter (such as UE 110 or wireless network node 120) or by a control device configured to potentially control its functions when installed therein.

[0074] The first method may include, in step 510, generating a trellis-coded modulation symbol sequence in a complex QPSK constellation using trellis codes for a binary data sequence. The first method may further include, in step 520, generating a DFT pre-coded OFDM signal based at least on the trellis-coded modulation symbol sequence. Finally, the first method may include, in step 530, performing transmission based on the generated DFT pre-coded OFDM signal, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis codes, and wherein the absolute difference between two consecutive phase transitions determined by the trellis codes is at most π / 2.

[0075] Figure 6 This is a flowchart of a second method according to at least some example embodiments. The steps of the second method can be performed by any wireless receiver (such as UE 110 or wireless network node 120) or by a control device configured to potentially control its functions when installed therein.

[0076] The second method may include, in step 610, receiving a DFT-pre-coded OFDM signal. The second method may further include, in step 620, determining a trellis-coded modulation symbol sequence from the DFT-pre-coded OFDM signal. Finally, the second method may include, in step 630, determining a binary data sequence from the trellis-coded modulation symbol sequence and based on the trellis code used to generate the trellis-coded modulation symbol sequence, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

[0077] It should be understood that the disclosed example embodiments are not limited to the specific structures, process steps, or materials disclosed herein, but are extended to their equivalents, as will be recognized by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting.

[0078] Throughout this specification, any reference to an exemplary embodiment or an exemplary embodiment implies that a particular feature, structure, or characteristic described in connection with the exemplary embodiment is included in at least one exemplary embodiment. Therefore, the phrases "in one exemplary embodiment" or "in an exemplary embodiment" appearing in various places throughout this specification do not necessarily refer to the same exemplary embodiment. Precise numerical values ​​are also disclosed where terms such as, for example, approximately or substantially, are used to refer to numerical values.

[0079] As used herein, for convenience, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list. However, these lists should be interpreted as if each member of the list were individually identified as a separate and unique member. Therefore, without indication to the contrary, any individual member of such a list should not be construed as a de facto equivalent of any other member of the same list solely based on their presentation in the common group. Furthermore, various exemplary embodiments and examples may be cited herein along with alternatives to their various components. It should be understood that such exemplary embodiments, examples, and alternatives should not be construed as de facto equivalents of each other, but should be considered as separate and autonomous representations.

[0080] In the example embodiments, an apparatus such as, for example, UE 110 or wireless network node 120 may include components for performing the example embodiments described above and any combination thereof.

[0081] In exemplary embodiments, a computer program may be configured to cause a method according to the above exemplary embodiments and any combination thereof. In exemplary embodiments, a computer program product embodied on a non-transitory computer-readable medium may be configured to control a processor to perform processes including the above exemplary embodiments and any combination thereof.

[0082] In example embodiments, an apparatus such as, for example, UE 110 or wireless network node 120 may include at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to perform at least the example embodiments described above and any combination thereof.

[0083] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more exemplary embodiments. Numerous specific details, such as examples of length, width, shape, etc., have been provided in the foregoing description to provide a thorough understanding of exemplary embodiments of this disclosure. However, those skilled in the art will recognize that this disclosure can be practiced without one or more specific details or using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring various aspects of this disclosure.

[0084] While the foregoing examples illustrate the principles of exemplary embodiments in one or more specific applications, it will be apparent to those skilled in the art that numerous modifications can be made to the form, use, and details of the implementations without inventive effort and without departing from the principles and concepts of this disclosure. Therefore, this disclosure is not intended to be limited except by the claims set forth below.

[0085] The verbs “comprising” and “including” are used herein as open-ended restrictions, neither excluding nor requiring the presence of any unlisted features. Unless otherwise expressly stated, the features recited in the dependent claims may be freely combined with each other. Furthermore, it should be understood that the use of “a” or “an,” i.e., the singular form, throughout this document does not exclude a plurality.

[0086] Industrial applicability At least some example implementations have found industrial applications in cellular communication networks, such as in 3GPP networks.

[0087] List of acronyms 3GPP Third Generation Partner Program ACLR adjacent channel leakage ratio BCJRBahl-Cocke-Jelinek-Raviv BPSK binary phase shift keying BS base station CCDF Complementary Cumulative Distribution Function DFT (Discrete Fourier Transform) DU Distribution Unit eMBB Enhanced Mobile Broadband FDSS frequency domain spectral shaping GSM Global Mobile Communication System IAB Integration Access and Backhaul IBE in-band firing IFFT (Inverse Fast Fourier Transform) IoT LPWA (Low Power Wide Area) LTE Long Term Evolution M2M (Machine-to-Machine) MPR maximum power reduction MT mobile terminal NFC Near Field Communication NR New Radio OBO output rollback OFDM (Orthogonal Frequency Division Multiplexing) OOB outside the band PAPR peak-to-average power ratio PRB Physical Resource Block PUCCH (Physical Uplink Control Channel) PUSCH Physical Uplink Shared Channel QAM Quadrature Amplitude Modulation QPSK quadrature phase shift keying RAT radio access technology RB resource blocks RF radio frequency RRC Radio Resource Control SEM Spectral Emission Mask SOVA soft-output Viterbi algorithm TRP transceiver point UE User Equipment UI User Interface WCDMA Wideband Code Division Multiple Access WiMAX Wireless Global Microwave Access Interoperability WLAN wireless local area network List of reference numerals

Claims

1. An apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by said at least one processor, causing the apparatus to at least: - For binary data sequences, trellis codes are used to generate trellis-coded modulation symbol sequences in a complex quadrature phase shift keying (QPSK) constellation; - Generate Discrete Fourier Transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signals based at least on the aforementioned grid-coded modulation symbol sequences; and Transmission is performed based on the generated DFT pre-coded OFDM signal, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

2. The apparatus of claim 1, wherein the trellis code is a two-state recursive trellis code comprising a first state and a second state, wherein the phase transition for generating the corresponding trellis codec modulation symbol when transitioning from the first state to the second state or from the second state to the first state is equal to 0, wherein the phase transition for generating the corresponding trellis codec modulation symbol when transitioning back from the first state is equal to +π / 2, and wherein the phase transition for generating the corresponding trellis codec modulation symbol when transitioning back from the second state is equal to -π / 2.

3. The apparatus according to claim 1 or 2, wherein the apparatus is further configured to: - Determine that the first phase transition of the first grid-coded modulation symbol used to generate the sequence is 0; and - Based on determining that the first phase transition is 0, the second phase transition for generating the second continuous grid coding / decoding modulation symbol of the sequence is determined to be -π / 2, 0, or +π / 2.

4. The apparatus according to any one of the preceding claims, wherein the apparatus is further configured to: - The first phase transition used to generate the first grid-coded modulation symbol of the sequence is determined to be -π / 2; and - Based on the determination that the first phase transition is -π / 2, the second phase transition used to generate the second continuous grid encoding / decoding modulation symbol of the sequence is determined to be -π / 2 or 0.

5. The apparatus according to any one of the preceding claims, wherein the apparatus is further configured to: - The first phase transition of the first grid-coded modulation symbol used to generate the sequence is determined to be +π / 2; and - Based on determining that the first phase transition is +π / 2, the second phase transition used to generate the second continuous grid encoding / decoding modulation symbol of the sequence is determined to be either +π / 2 or 0.

6. The apparatus according to any one of the preceding claims, wherein the apparatus is further configured to: - Insert additional modulation symbols interleaved with the lattice-coded modulation symbol sequence, wherein the interleaved modulation symbols have the same amplitude as the previous and consecutive lattice-coded modulation symbols, and a phase interpolated from the phase of the previous and consecutive lattice-coded modulation symbols; and - The DFT pre-coded OFDM signal is generated based at least on the grid-coded modulation symbol sequence and the interleaved modulation symbols.

7. The apparatus of claim 6, wherein the apparatus is further configured to: - By truncating the DFT field sequence to a size of M+E The preferred bandwidth of each DFT frequency grid is used as the input for Inverse Fast Fourier Transform (IFFT) to generate the DFT pre-coded OFDM signal, wherein... M Indicates the length of the sequence, and E Represents a positive integer, where 0 ≤ E ≤ M .

8. The apparatus according to claim 7, wherein... M+E Each DFT frequency grid is centered around the DC frequency grid of the DFT domain sequence.

9. The apparatus according to any one of claims 6 to 8, wherein the apparatus is further configured to: - Determine whether the size of the allocated transmission in the frequency domain is below a threshold; and The insertion is performed when the size of the allocated transfer is less than or equal to the threshold.

10. The apparatus according to any one of claims 6 to 9, wherein the apparatus is further configured to: - Determine whether the size of the allocated transmission in the frequency domain is below a threshold; and - When the size of the allocated transmission exceeds the threshold, the allocation is considered invalid.

11. The apparatus of claim 9 or claim 10, wherein the threshold is half the maximum allocation size of the transmission in the frequency domain.

12. The apparatus according to any one of the preceding claims, wherein the apparatus is further configured to: - One bit of each binary data sequence generates a grid-coded modulation symbol sequence.

13. A method comprising: - For binary data sequences, trellis codes are used to generate trellis-coded modulation symbol sequences in a complex quadrature phase shift keying (QPSK) constellation; - Generate Discrete Fourier Transform (DFT) pre-coded orthogonal frequency division multiplexing (OFDM) signals based at least on the grid-coded modulation symbol sequence; as well as Transmission is performed based on the generated DFT pre-coded OFDM signal, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

14. An apparatus comprising at least one processor and at least one memory storing instructions, the instructions, when executed by said at least one processor, causing the apparatus to at least: - Receive Discrete Fourier Transform (DFT) pre-encoded and decoded Orthogonal Frequency Division Multiplexing (OFDM) signals; - Determine the trellis-coded modulation symbol sequence from the DFT pre-coded OFDM signal; and - A binary data sequence is determined from the trellis-coded modulation symbol sequence and based on the trellis code used to generate the trellis-coded modulation symbol sequence, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

15. The apparatus of claim 14, wherein the lattice code is a two-state recursive lattice code comprising a first state and a second state, wherein the phase transition for decoding the corresponding lattice codec modulation symbol is equal to 0 when transitioning from the first state to the second state or from the second state to the first state, wherein the phase transition for decoding the corresponding lattice codec modulation symbol is equal to +π / 2 when transitioning back from the first state to the first state, and wherein the phase transition for decoding the corresponding lattice codec modulation symbol is equal to -π / 2 when transitioning back from the second state to the second state.

16. A method comprising: - Receive Discrete Fourier Transform (DFT) pre-encoded and decoded Orthogonal Frequency Division Multiplexing (OFDM) signals; - Determine the trellis-coded modulation symbol sequence from the DFT pre-coded OFDM signal; as well as - A binary data sequence is determined from the trellis-coded modulation symbol sequence and based on the trellis code used to generate the trellis-coded modulation symbol sequence, wherein the phase transition between two consecutive trellis-coded modulation symbols of the sequence is determined by the trellis code, and wherein the absolute difference between two consecutive phase transitions determined by the trellis code is at most π / 2.

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