US-12627549-B2 - Multiple symbol shift configuration

US12627549B2US 12627549 B2US12627549 B2US 12627549B2US-12627549-B2

Abstract

A method for reducing inter symbol interference (ISI) and inter carrier interference (ICI) in transmissions between a sender and a recipient within a wireless communication network. For at least one multicarrier symbol comprising a first subcarrier modulated with an original reference signal and multiplexed with a second subcarrier modulated with an original payload signal. The method includes applying a multiple symbol shift configuration on at least a second multicarrier symbol adjacent to the first multicarrier symbol by repeating the original reference signal and the original payload signal in the second multicarrier symbol on respective subcarriers and applying a linear phase shift to each repeated reference signal and payload signal. The same linear phase shift is used for both the repeated reference signal and the repeated payload signal.

Inventors

Robert Baldemair
Joao Vieira
Muris Sarajlic

Assignees

TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Dates

Publication Date: 20260512
Application Date: 20210525

Claims (15)

1 . A method for reducing inter symbol interference (ISI) and inter carrier interference (ICI) in transmissions between a sender and a recipient within a wireless communication network, at least a first multicarrier symbol comprising a first subcarrier modulated with an original reference signal and multiplexed with a second subcarrier modulated with an original payload signal, the method comprising: applying a multiple symbol shift configuration on at least a second multicarrier symbol adjacent to the first multicarrier symbol by: repeating the original reference signal and the original payload signal in the second multicarrier symbol on respective subcarriers; and applying a linear phase shift to the repeated reference signal and the repeated payload signal, the same linear phase shift being used for both the repeated reference signal and the repeated payload signal.
2 . The method according to claim 1 , wherein the original reference signal is at least one of a Demodulation Reference Signal (DMRS), Channel State Information Reference signal (CSI-RS) or a Sounding Reference Signal (SRS), or any other reference signal compatible with a multiple symbol structure.
3 . The method according to claim 1 , wherein the original payload signal is a Data signal or control signal.
4 . The method according to claim 1 , further comprising: determining whether a performance criterion is met prior to applying the multiple symbol shift configuration; and applying the multiple symbol shift configuration when it is determined that the performance criterion is met.
5 . The method according to claim 4 , wherein determining whether the performance criterion is met comprises at least one of the following: determining whether an anticipated delay spread in the wireless communication network exceeds a delay spread threshold value; determining whether a high-order modulation coding scheme is used for transmissions within the wireless communication network; determining whether there is a risk that a cyclic prefix applied to the multicarrier symbol is shorter than an impulse response associated with transmitting the multicarrier symbol; and receiving from the recipient an indication that the multiple symbol shift configuration is to be applied, wherein the recipient is one of a wireless communication device and a network node.
6 . The method according to claim 1 , further comprising: instructing the recipient to apply the multiple symbol configuration, wherein the recipient is at least one of a wireless communication device and a network node.
7 . An apparatus for reducing inter symbol interference (ISI) and inter carrier interference (ICI) in transmissions between a sender and a recipient within a wireless communication network, the apparatus comprising controlling circuitry configured to cause, for at least a first multicarrier symbol comprising a first subcarrier modulated with an original reference signal and multiplexed with a second subcarrier modulated with an original payload signal: application of a multiple symbol shift configuration on at least a second multicarrier symbol adjacent to the first multicarrier symbol by: repetition of the original reference signal and the original payload signal in the second multicarrier symbol on respective subcarriers; and application of a linear phase shift to each repeated reference signal and payload signal, wherein the same linear phase shift is used for both the repeated reference signal and the repeated payload signal.
8 . The apparatus according to claim 7 , wherein the original reference signal is at least one of a Demodulation Reference Signal (DMRS), Channel state information Reference signal (CSI-RS) or a Sounding Reference Signal (SRS), or any other reference signal compatible with a multiple symbol structure.
9 . The apparatus according to claim 7 , wherein the original payload signal is a Data signal or Control signal.
10 . The apparatus according to claim 7 , wherein the controlling circuitry is further configured to cause: determination of whether a performance criterion is met prior to causing application of the multiple symbol shift configuration; and application of the multiple symbol shift configuration when it is determined that the performance criterion is met.
11 . The apparatus according to claim 10 , wherein the determination of whether the performance criterion is met comprises at least one of the following: determination of whether an anticipated delay spread in the wireless communication network exceeds a delay spread threshold value; determination of whether a high modulation coding scheme is used for transmissions within the wireless communication network; determination of whether there is a risk that a cyclic prefix applied to the multicarrier symbol is shorter than an impulse response associated with transmitting the multicarrier symbol; and reception of an indication that the multiple symbol configuration is to be applied from the recipient, wherein the recipient is one of a wireless communication device and a network node.
12 . The apparatus according to claim 7 , wherein the controlling circuitry is configured to cause: instruction of the recipient, to apply the multiple symbol shift configuration, wherein the recipient is at least one of a wireless communication device and a network node.
13 . The apparatus according to claim 7 , the apparatus being comprised in a network node configured to operate in a wireless communication network and configured to serve at least one wireless communication device, the network node operably connected to the wireless communication network.
14 . The apparatus according to claim 7 , the apparatus being comprised in a wireless communication device configured to be operably connected to a wireless communication network and to be served by at least one network node associated with the wireless communication network.
15 . A non-transitory computer storage medium storing a computer program, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out a method for reducing inter symbol interference (ISI) and inter carrier interference (ICI) in transmissions between a sender and a recipient within a wireless communication network, at least a first multicarrier symbol comprising a first subcarrier modulated with an original reference signal and multiplexed with a second subcarrier modulated with an original payload signal, the method comprising: applying a multiple symbol shift configuration on at least a second multicarrier symbol adjacent to the first multicarrier symbol by: repeating the original reference signal and the original payload signal in the second multicarrier symbol on respective subcarriers; and applying a linear phase shift to the repeated reference signal and the repeated payload signal, the same linear phase shift being used for both the repeated reference signal and the repeated payload signal.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a Submission Under 35 U.S.C. § 371 for U.S. National Stage Patent Application of International Application Number: PCT/EP2021/063791, filed May 25, 2021 entitled “MULTIPLE SYMBOL SHIFT CONFIGURATION,” the entirety of which is incorporated herein by reference. TECHNICAL FIELD The present invention relates generally to the field of wireless communication. More particularly, it relates to methods and apparatuses for reducing inter-carrier interference (ICI) and inter-symbol interference (ISI) in a carrier. BACKGROUND In a multicarrier system such as an Orthogonal Frequency Division Multiplex (OFDM) system, a cyclic prefix is typically used to enable simple frequency-domain equalization. The cyclic prefix turns the linear convolution of the channel into a circular convolution. Typically, the cyclic prefix of an OFDM-symbol is obtained by copying the last samples of the symbol and attaching them to the beginning. Hence, a circular signal structure is obtained since the first and last samples in the symbol are equal in each OFDM symbol. In order to function properly, the cyclic prefix should preferably be longer (i.e. comprise enough symbol samples) than the impulse response of the channel (or at least the part of the impulse response of the channel that contains most energy) together with any other components in the transmission chain which could introduce linear distortions. Such components may e.g. be transmit- and receiver filters. Furthermore, the cyclic prefix should preferably also provide margins for non-perfect time synchronization. If the cyclic prefix is too short, inter-symbol and inter-carrier interference (ISI and ICI) may typically occur because interference from the previous symbol may smear into the current one and the transients at the beginning of the current symbol are not yet completely decayed. One strategy for handling this problem is typically to rely on advanced receivers such as time-domain equalizers that try to shorten the overall impulse response and/or advanced frequency-domain equalizers that try to minimize ISI and ICI. However, such advanced receivers require an accurate estimate of the impulse response to work. However, with an insufficient cyclic prefix, the channel estimate is already corrupted which makes the above proposed techniques difficult or even impossible. Therefore, there is a need for methods and apparatuses for robust channel estimation in wireless communication systems that utilize multicarrier transmissions. SUMMARY It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. It is an object of some embodiments to solve or at least mitigate some of the above disadvantages and to provide method, apparatus, computer program product, network node and wireless communication device for reducing ISI and ICI. According to a first aspect, this is achieved by a method for reducing inter symbol interference (ISI) and inter carrier interference (ICI) in transmissions between a sender and a recipient within a wireless communication network. For at least one multicarrier symbol comprising a first subcarrier modulated with an original reference signal and multiplexed with a second subcarrier modulated with an original payload signal, the method comprises applying a multiple symbol shift configuration on at least a second multicarrier symbol adjacent to the first multicarrier symbol by repeating the original reference signal and the original payload signal in the second multicarrier symbol on respective subcarriers and by applying a linear phase shift to each repeated reference signal and payload signal. The same linear phase shift is used for both the repeated reference signal and the repeated payload signal. In some embodiments, the method may further comprise that the original reference signal is at least one of a Demodulation Reference Signal (DMRS), a Channel State Information Reference Signal (CSI-RS) or a Sounding Reference Signal (SRS) or any other reference signal compatible with a multiple symbol structure. In some embodiments the method may further comprise that the original payload signal is a Data signal or control signal. In some embodiments, the method may further comprise determining whether a performance criterion is met prior to applying the multiple symbol shift configuration; and performing the step of applying the multiple symbol shift configuration when it is determined that the performance criterion is met. In some embodiments, the method may further comprise determining whether the performance criterion is met by determining at least one of the following: determining whether an anticipated delay spread in the wireless communication network exceeds a delay spr