Apparatus and method for transmitting and receiving data in communication system

A method for transmitting and receiving data in a communication system includes adding symbols to both ends of a transmitted signal block, filtering the transmitted signal block, removing the symbols from the filtered transmitted signal block and transmitting the transmitted signal block to a receiver through a channel. A transmitter includes a controller configured to add symbols to both ends of a transmitted signal block through the symbol adder, filter the transmitted signal block, remove the symbols from the filtered transmitted signal block through the symbol remover, and transmit the transmitted signal block through the transceiver to a receiver through a channel. A receiver includes a controller configured to add symbols to both ends of the received signal block through the symbol adder, filter the received signal block and reconstruct data from the received signal block.

The present application is related to and claims the priority under 35 U.S.C. §119(a) to Korean Application Serial No. 10-2015-0151181, which was filed in the Korean Intellectual Property Office on Oct. 29, 2015, the entire content of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and a method for transmitting and receiving data in a communication system.

BACKGROUND

Demands for improvement in system capacity are growing due to an increase in the amount of data used by users. A non-orthogonal transmission scheme is considered to be a solution to such demands. In particular, faster-than-Nyquist (FTN) signaling is favored as a non-orthogonal transmission method for increasing a data rate while simultaneously improving spectrum efficiency.

Here, FTN signaling is a transmission scheme in which symbols are transmitted at a rate higher than the Nyquist rate at which orthogonality between symbols is satisfied. That is, FTN signaling is a transmission scheme of transmitting time-domain sampling pulses at an artificially faster symbol rate than Nyquist signaling in order to break orthogonality between symbols.

SUMMARY

However, since FTN signaling transmits symbols at a rate higher than the Nyquist rate, inter-symbol interference (ISI) occurs. Further, ISI causes the occurrence of inter-block interference (MI) in a block-based transmission system. Since IBI damages data, a method for eliminating IBI is additionally needed.

To address the above-discussed deficiencies, it is a primary object to provide a method and an apparatus for eliminating IBI from a block using the addition and removal of symbols.

Another exemplary embodiment of the present disclosure proposes a method and an apparatus for equalizing a block in view of both ISI caused by FTN and ISI caused by a channel in order to reduce the computational complexity of a receiver.

Further, still another exemplary embodiment of the present disclosure proposes a method and an apparatus for transmitting a block via PE in view of ISI in order to reduce the computational complexity of a receiver.

In addition, yet another exemplary embodiment of the present disclosure proposes a method and an apparatus for allowing a transmitter to pre-equalize a block in view of ISI and allowing a receiver to additionally equalize the block in view of remaining ISI in order to reduce the computational complexity of the receiver.

An operating method of a transmitter according to an exemplary embodiment of the present disclosure may include: adding symbols to both ends of a transmitted signal block; filtering the transmitted signal block; removing the symbols from the filtered transmitted signal block; and transmitting the transmitted signal block to a receiver through a channel.

An operating method of a receiver according to an exemplary embodiment of the present disclosure may include: adding symbols to both ends of a received signal block received from a transmitter through a channel; filtering the received signal block; removing the symbols from the filtered received signal block; and reconstructing data from the received signal block.

A transmitter according to an exemplary embodiment of the present disclosure may include: a transceiver; a symbol adder configured to add symbols; a symbol remover configured to remove the symbols; and a controller configured to add symbols to both ends of a transmitted signal block through the symbol adder, to filter the transmitted signal block, to remove the symbols from the filtered transmitted signal block through the symbol remover, and to transmit the transmitted signal block through the transceiver to a receiver through a channel.

A receiver according to an exemplary embodiment of the present disclosure may include: a transceiver; a symbol adder configured to add symbols; a symbol remover configured to remove the symbols; and a controller configured to receive a received signal block through the transceiver from a transmitter through a channel, to add symbols to both ends of the received signal block through the symbol adder, to filter the received signal block, to remove the symbols from the filtered received signal block through the symbol remover, and to reconstruct data from the received signal block.

DETAILED DESCRIPTION

The present disclosure may have various embodiments, and modifications and changes may be made therein. Therefore, the present disclosure will be described in detail with reference to particular embodiments shown in the accompanying drawings. However, it should be understood that the present disclosure is not limited to the particular embodiments, but includes all modifications/changes, equivalents, and/or alternatives falling within the spirit and the scope of the present disclosure. In describing the drawings, similar reference numerals may be used to designate similar elements.

The terms “have”, “may have”, “include”, or “may include” used in the various embodiments of the present disclosure indicate the presence of disclosed corresponding functions, operations, elements, and the like, and do not limit additional one or more functions, operations, elements, and the like. In addition, it should be understood that the terms “include” or “have” used in the various embodiments of the present disclosure are to indicate the presence of features, numbers, steps, operations, elements, parts, or a combination thereof described in the specifications, and do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or a combination thereof.

The terms “A or B”, “at least one of A or/and B” or “one or more of A or/and B” used in the various embodiments of the present disclosure include any and all combinations of words enumerated with it. For example, “A or B”, “at least one of A and B” or “at least one of A or B” means (1) including at least one A, (2) including at least one B, or (3) including both at least one A and at least one B.

Although the term such as “first” and “second” used in various embodiments of the present disclosure may modify various elements of various embodiments, these terms do not limit the corresponding elements. For example, these terms do not limit an order and/or importance of the corresponding elements. These terms may be used for the purpose of distinguishing one element from another element. For example, a first user device and a second user device all indicate user devices and may indicate different user devices. For example, a first element may be named a second element without departing from the scope of right of various embodiments of the present disclosure, and similarly, a second element may be named a first element.

It will be understood that when an element (e.g., first element) is “connected to” or “(operatively or communicatively) coupled with/to” to another element (e.g., second element), the element may be directly connected or coupled to another element, and there may be an intervening element (e.g., third element) between the element and another element. To the contrary, it will be understood that when an element (e.g., first element) is “directly connected” or “directly coupled” to another element (e.g., second element), there is no intervening element (e.g., third element) between the element and another element.

The expression “configured to (or set to)” used in various embodiments of the present disclosure may be replaced with “suitable for”, “having the capacity to”, “designed to”, “adapted to”, “made to”, or “capable of” according to a situation. The term “configured to (set to)” does not necessarily mean “specifically designed to” in a hardware level. Instead, the expression “apparatus configured to . . . ” may mean that the apparatus is “capable of . . . ” along with other devices or parts in a certain situation. For example, “a processor configured to (set to) perform A, B, and C” may be a dedicated processor, e.g., an embedded processor, for performing a corresponding operation, or a generic-purpose processor, e.g., a Central Processing Unit (CPU) or an application processor (AP), capable of performing a corresponding operation by executing one or more software programs stored in a memory device.

FIG. 1is a diagram of a communication system according to an exemplary embodiment of the present disclosure.

Referring toFIG. 1, a communication system includes a transmitter101, a receiver103, and a channel105.

Describing each component, the channel105is a transmission path for carrying data and can carry data, transmitted from the transmitter101, to the receiver103.

The transmitter101can generate data and can transmit the generated data through the channel105. For example, the transmitter101can generate and transmit data using faster-than-Nyquist (FTN) signaling. Here, FTN signaling is a transmission scheme in which symbols are transmitted at a rate higher than a Nyquist rate at which orthogonality between symbols is satisfied. That is, FTN signaling is a transmission scheme of transmitting time-domain sampling pulses at an artificially faster symbol rate than Nyquist signaling in order to break orthogonality between symbols. Here, Nyquist signaling is a transmission scheme of transmitting symbols at the Nyquist rate.

Since FTN signaling transmits symbols faster than Nyquist signaling, the transmitter101can reduce signaling time between transmitted symbols. Due to the reduction in signaling time between symbols, FTN signaling can improve spectral efficiency while allowing an increase in data rate of the transmitter101.

However, since FTN signaling transmits symbols at a rate higher than the Nyquist rate, inter-symbol interference (ISI) inevitably occurs. Since the transmitter101transmits data based on a unit of a block including a plurality of symbols (for example, a transmitted signal block), not a unit of a symbol, inter-block interference (IBI) occurs in the transmitter101.

For example, to eliminate IBI, the transmitter101can add a cyclic prefix (CP) and a cyclic suffix (CS) (hereinafter referred to as an “FTN CP and CS”) to a transmitted signal block at a front end of a pulse shaping filter employing FTN signaling. The transmitter101can perform FTN on the FTN CP and CS-added transmitted signal block through the pulse shaping filter. Here, the transmit101can remove the FTN CP and CS from the FTN CP and CS-added transmitted signal block at a rear end of the pulse shaping filter. That is, the transmitter101can perform FTN CP and CS addition and removal, thereby eliminating IBI by the pulse shaping filter from the transmitted signal block. The transmitter101can transmit the IBI-eliminated transmitted signal block to the receiver103through the channel105.

The receiver103can receive data through the channel105and can reconstruct the received data. For example, the receiver103can receive and reconstruct data using FTN signaling.

For example, to eliminate IBI inevitably occurring in FTN signaling, the receiver103can add an FTN CP and CS to a received signal block at a front end of a matched filter employing FTN signaling. The receiver103can perform FTN on the FTN CP and CS-added received signal block through the matched filter. Here, the FTN CP and CS of the received signal block can include IBI caused by the matched filter performing FTN.

The receiver103can remove the FTN CP and CS from the FTN CP and CS-added received signal block at a rear end of the matched filter. That is, the receiver103can perform FTN CP and CS addition and removal, thereby eliminating IBI by the matched filter from the received signal block. The receiver103can reconstruct data using the IBI-eliminated received signal block.

FIG. 2is a block diagram of a transmitter according to a first exemplary embodiment of the present disclosure.

Referring toFIG. 2, a transmitter101can include a controller201, an FTN CP and CS adder203, a transmit (Tx) pulse shaping filter205, an FTN CP and CS remover207, a channel CP adder209, and an up converter211.

Describing each component, the FTN CP and CS adder203can receive data based on a unit of a transmitted signal block according to control by the controller201. For example, a transmitted signal block can include encoded symbols. The FTN CP and CS adder203can add an FTN CP and CS to the received transmitted signal block to eliminate IBI caused by the Tx pulse shaping filter205and can output the FTN CP and CS-added transmitted signal block to the Tx pulse shaping filter205.

For example, as illustrated inFIG. 3, the FTN CP and CS adder203can receive successive transmitted signal blocks301and303, can add a CP305to the front of the transmitted signal block301, and can add a CS307to the rear thereof. Further, the FTN CP and CS adder203can add a CP309to the front of the transmitted signal block303and can add a CS311to the rear thereof. For example, the lengths of the CPs and CSs can be determined based on the performance of the Tx pulse shaping filter205, for example, the length of a tap. Here, the tap is the maximum time-axis length of the Tx pulse shaping filter205or a receive (Rx) matched filter and is determined by sampling. For example, referring toFIG. 32, the Tx pulse shaping filter205has the maximum amplitude in a ninth time sample, and a graph3201can have eight taps right and left based on the ninth time sample3203.

For example, the FTN CP and CS adder203can generate an FTN CP and CS-added transmitted signal block using the following equation.
d=Cpd[Equation 1]

Here,ddenotes an FTN CP and CS-added transmitted signal block and has an (N+2P) size. d denotes a transmitted signal block, d=[d0, . . . , dk, . . . , dN−1]TεCN×1. Cpdenotes an FTN CP and CS adding matrix and has an (N+2P)×N size. P denotes the length of each of a CP and a CS.

The Tx pulse shaping filter205can receive the FTN CP and CS-added transmitted signal block, can filter the transmitted signal block in a base band, and can apply FTN to the filtered transmitted signal block according to control by the controller201. For example, the Tx pulse shaping filter205can be a squeezed sampling pulse shaping filter.

For example, applying FTN to a transmitted signal block can mean transmitting a transmitted signal via sampling faster than the existing Nyquist rate. That is, applying FTN to a transmitted signal block can mean that the Tx pulse shaping filter transmits transmitted signals to overlap to be artificially non-orthogonal in terms of time (the existing Nyquist rate allows transmitted signals to be transmitted not to overlap in terms of time) so that the transmission is performed at an artificially faster symbol rate to break orthogonality between symbols.

For example, as illustrated inFIG. 3, the Tx pulse shaping filter205can filter the FTN CP and CS-added transmitted signal blocks301and303with a pulse-shaped filter for sampling, thereby generating the filtered transmitted signal blocks301and303(indicated with diagonal lines). For example, the FTN CP305and CS307of the transmitted signal block301can include ISI and IBI caused by the Tx pulse shaping filter205performing FTN. The FTN CP309and CS311of the transmitted signal block303can include IBI caused by the Tx pulse shaping filter205performing FTN. The Tx pulse shaping filter205can output the FTN-applied transmitted signal block to the FTN CP and CS remover207.

For example, the Tx pulse shaping filter205can generate an FTN-applied transmitted signal block using the following equation.
t=Gtd[Equation 2]

The FTN CP and CS remover207can receive the FTN-applied transmitted signal block and can remove the FTN CP and CS from the received transmitted signal block according to control by the controller201. For example, as illustrated inFIG. 3, the FTN CP and CS remover207can remove the FTN CP305and CS307from the transmitted signal block301filtered with the pulse-shaped filter for sampling and can remove the FTN CP309and CS311from the transmitted signal block303filtered with the pulse-shaped filter for sampling. The FTN CP and CS remover207can output the FTN CP and CS-removed transmitted signal block to the channel CP adder209.

For example, the FTN CP and CS remover207can generate an FTN CP and CS-removed transmitted signal block using the following equation.
t=Rpt=Rpt=RpGtd=RpGtCpd=Gtcd[Equation 3]

The channel CP adder209can receive the FTN CP and CS-removed transmitted signal block from the FTN CP and CS remover207and can add a CP for removing IBI caused by a channel (hereinafter, referred to as a channel CP) to the received transmitted signal block according to control by the controller201. For example, as illustrated inFIG. 3, the channel CP adder209can add a channel CP313to the transmitted signal block301and can add a channel CP315to the transmitted signal block303. The channel CP adder209can output the channel CP-added transmitted signal block to the up converter211. For example, the channel CP can be a guard interval (GI) between transmitted blocks, and the length of the channel CP can be determined based on the length of a channel impulse response (CIR).

Suppose that the channel105is a frequency-adaptive channel, a multipath channel has a causal link, and the channel105has a normalized discrete CIR with a length of L=Tm/(ρTs). Here, Tmdenotes a channel delay spread sampled at a squeezed sampling time ρTs. Further, suppose that channel coefficients are known to the receiver103and are constants during the entire transmission of blocks.

In this case, the channel CP adder209can generate a channel CP-added transmitted signal block using the following equation.
t′=CLt[Equation 4]

Here, t′ denotes a channel CP-added transmitted signal block. t denotes an FTN CP and CS-removed transmitted signal block. CLdenotes an (N+L−1)×1 channel CP adding matrix. If a channel CP has a symbol length of (L−1), CLcan be represented by the following equation.

The up converter211can receive the channel CP-added transmitted signal block from the channel CP adder209and can modulate (for example, up-convert) the received transmitted signal block into a radio frequency (RF) in order to transmit the transmitted signal block through the channel105according to control by the controller201.

The controller201can control overall operations of the transmitter101. For example, the controller201can control the FTN CP and CS adder203, the Tx pulse shaping filter205, the FTN CP and CS remover207, the channel CP adder209, and the up converter211.

For example, the controller201can add an FTN CP and CS to a transmitted signal block through the FTN CP and CS adder203. The controller201can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling and can perform FTN through the Tx pulse shaping filter205. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter205performing FTN. The controller201can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FTN CP and CS remover207.

The controller201can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder209. The controller201can up-convert the channel CP-added transmitted signal block into an RF through the up converter211and can transmit the transmitted signal block through the channel105.

FIG. 4is a block diagram of a receiver according to the first exemplary embodiment of the present disclosure.

Referring toFIG. 4, a receiver103can include a controller401, a down converter403, a channel CP remover405, an FTN CP and CS adder407, an receive (Rx) matched filter409, an FTN CP and CS remover411, a fast Fourier transform (FFT) unit413, a frequency-domain equalizer (FDE)415, and an inverse FFT (IFFT) unit417.

Describing each component, the down converter403can receive a received signal block via a receiving antenna and can down-convert the received signal block into a base band. For example, as illustrated inFIG. 5, the down converter403can receive a received signal block501with a channel CP505added and a received signal block503with a channel CP507added. For example, the received signal block can include a plurality of received symbols.

For example, the received signal block can be represented by the following equation.
x=Ht′+nc[Equation 6]

The channel CP remover405can receive the channel CP-added received signal block from the down converter403and can remove a channel CP from the received signal block. For example, as illustrated inFIG. 5, the channel CP remover405can remove the channel CP505from the received signal block501and can remove the channel CP507from the received signal block503. The channel CP remover405can output the channel CP-removed received signal block to the FTN CP and CS adder407.

For example, the channel CP remover405can generate a channel CP-removed received signal block using the following equation.

Here,xdenotes a channel CP-removed received signal block. X denotes a received signal block RLdenotes an N×(N+L−1) channel CP removing matrix, RL=[ON×(L−1)IN]. Hcdenotes an (N×N) circulant matrix for a squeezed sampling channel matrix H, Hc=RLHCL. n denotes an (N×1) additive Gaussian noise vector, n=RLnc.

The FTN CP and CS adder407can receive the channel CP-removed received signal block from the channel CP remover405and can add an FTN CP and CS to the received signal block to eliminate IBI caused by the Rx matched filter performing FTN. For example, as illustrated inFIG. 5, the FTN CP and CS adder407can add a CP509to the front of the received signal block501and can add a CS511to the rear of the received signal block501. Further, the FTN CP and CS adder407can add a CP513to the front of the received signal block503and can add a CS515to the rear of the received signal block503. The FTN CP and CS adder407can output the FTN CP and CS-added received signal block to the Rx matched filter409.

For example, the length of each of the FTN CP and CS can be determined on the performance of the Rx matched filter409, for example, the length of a tap of the Rx matched filter409. For example, the length of each of the FTN CP and CS in the receiver103can be the same as the length of each of the FTN CP and CS in the transmitter101. For another example, the length of each of the FTN CP and CS in the receiver103can be different from the length of each of the FTN CP and CS in the transmitter101.

For example, the FTN CP and CS adder407can generate an FTN CP and CS-added received signal block using the following equation.
b=CMx[Equation 8]

Herebdenotes an FTN CP and CS-added received signal block and has an (N+2M)×1 size.xdenotes a channel CP-removed received signal block. CMdenotes an (N+2M)×N FTN CP and CS adding matrix. M denotes the length of each of an FTN CP and CS.

The Rx matched filter409can receive the FTN CP and CS-added received signal block from the FTN CP and CS adder407, can filter the received signal block in a base band, and can apply FTN to the filtered received signal block. For example, the Rx matched filter409can be a squeezed sampling matched filter.

For example, applying FTN to a received signal block can mean receiving a received signal via sampling faster than the existing Nyquist rate. That is, when the Tx pulse shaping filter205in the transmitter transmits transmitted signals to overlap to be artificially non-orthogonal in terms of time so that the transmission is performed at an artificially faster symbol rate to break orthogonality between symbols, applying FTN to a received signal block can mean that received signals are received via sampling to be non-orthogonal in terms of time (faster than the Nyquist) so that sampling is performed in synchronization with the transmitter.

For example, as illustrated inFIG. 5, the Rx matched filter409can filter the FTN CP and CS-added received signal blocks501and503with a pulse-shaped filter for sampling, thereby generating the filtered received signal blocks501and503(indicated with diagonal lines). For example, the FTN CP509and CS511of the received signal block501can include IBI caused by the Rx matched filter409performing FTN. The FTN CP513and CS515of the received signal block503can include IBI caused by the Rx matched filter409performing FTN. The Rx matched filter409can output the FTN-applied received signal block to the FTN CP and CS remover411.

For example, the Rx matched filter409can generate an FTN-applied received signal block using the following equation.
v=Grb=GrCMx[Equation 9]

The FTN CP and CS remover411can receive the FTN-applied received signal block from the Rx matched filter409and can remove the FTN CP and CS from the received signal block. For example, as illustrated inFIG. 5, the FTN CP and CS remover411can remove the FTN CP509and CS511from the received signal block501and can remove the FTN CP513and CS515from the received signal block503. The FTN CP and CS remover411can output the FTN CP and CS-removed received signal block to the FFT unit413.

For example, the FTN CP and CS remover411can generate an FTN CP and CS-removed received signal block using the following equation.
v=RMv=RMGrCMx=Grcx[Equation 10]

To reconstruct data (d) transmitted from the transmitter101, v can be derived as follows.

Equation 11 shows that frequency-domain equalization can be applied to an FTN CP and CS-removed received signal block v via a discrete Fourier transform (DFT or an FFT) and an inverse DFT (IDFT or an IFFT) using respective cyclic structures of circulant matrices Hc, Grc, and Gtc.

Particularly, all circulant matrices share the same eigenvectors. That is, the same single DFT matrix supporting all circulant matrices can be applied to GrcHcGtcin Equation 11. Then, a circulant channel matrix Hccan be diagonalized by a single DFT matrix F 2 CN into Hc=FHΛcF. Here, Λcis a diagonal matrix of the circulant channel matrix, which includes diagonal elements [λc,0, . . . , λc,N−1]. Circulant sampling filter matrices Grcand Gtccan be diagonalized into Grc=FHΛrcF and Gtc=FHΛtcF. Here, Λrcand Λtcare diagonal matrices of the circulant sampling filter matrices Grcand Gtc.

Therefore, GrcHcGtccan be represented by the following equation.

Here, Λαdenotes all circulant matrices and can be represented by Λα=ΛrcΛcΛtc. A DFT matrix has a single attribute, for example, FHF=IN.

According to Equation 12, the receiver103converts a time-domain received signal block into a frequency-domain received signal block by applying a DFT matrix (or FFT matrix) F to the time-domain received signal block, performs frequency-domain equalization on the converted received signal block, and converts the equalized received signal block with an IDFT matrix (or IFFT matrix), thereby obtaining estimated data {circumflex over (d)} of time-domain transmitted data d.

Based on this result, the FFT unit413, the FDE415, and the IFFT417can operate as follows.

The FFT unit413can perform an FFT algorithm on the time-domain received signal block to convert the received signal block from the time domain to the frequency domain and can output the converted received signal block to the FDE415.

For example, the FFT unit413can generate a frequency-domain received signal block using the following equation.

Here, Zftnscfdedenotes a frequency-domain received signal block. The last term in Equation 13 can be derived from Fd=D and FGrcHcGtcFH=FFHΛαFFH=Λα.

The FDE415can receive the frequency-domain received signal block from the FFT unit413, can equalize the received signal block in the frequency domain, and can output the equalized received signal block to the IFFT unit417. Here, frequency-domain equalization refers to reducing amplitude or phase distortion to compensate for attenuation and propagation time delay deviation at each frequency in a transmission band.

For example, the FDE415can be a zero forcing (ZF) equalizer or minimum mean square error (MMSE) equalizer. For example, when the FDE415is a ZF equalizer, the frequency-domain received signal block Zftnscfdecan be equalized by multiplying Zftnscfdeby a weighting matrix of the ZF equalizer, Λα†=(ΛαHΛα)−1ΛαH.

For example, the ZF equalizer can be based on a Moore-Penrose pseudoinverse Λα†of Λαfor a pulse shaping filter, a matched filter, and a channel. In particular, when a channel Hcis estimated to have no zero on frequencies corresponding to frequency-domain data, the weighting matrix of the ZF equalizer can be Λα−1. A ZF criterion of the ZF equalizer can allow external ISI of Zftnscfdeto be completely eliminated. However, when there is a large number of Hcconditions (that is, when a coefficient of a channel impulse response is remarkably small due to serious channel attenuation caused by significant fading in a channel environment), elements of Λα−1nfhave a great variation, and thus a noise term can be amplified.

For another example, when the FDE415is a linear MMSE equalizer, the linear MMSE equalizer can be applied such that an increase in noise and reduction in ISI can be properly balanced. The linear MMSE equalizer can calculate a minimum mean squared error (MSE) between D (or d=FHD) and an estimate thereof {circumflex over (D)}ftnscfde=(Wre)Zftnscfde. Here, {circumflex over (D)}ftnscfdedenotes frequency-domain estimated data, and Wredenotes a weighting matrix for linear MMSE equalization.

Meanwhile, an MSE objective function (or a covariance matrix Ree) can be represented by the following equation.

By doing differentiation with respect to Wre, a weighting matrix Wrefor the linear MMSE equalizer can be acquired. Wreis represented by the following equation.
Wre=RDΛαH(Rnf+ΛαRDΛαH)−1[Equation 15]

By applying RD=σd2INand Rnf=E{FGrcn(FGrcn)H}=ΛrcFHE{nnH}FΛrcH=σn2ΛrcΛrcHto Equation 15, Wreis represented by the following equation.

For example, the linear MMSE equalizer can multiply the frequency-domain received signal block Zftnscfdeby the weighting matrix Wre, thereby generating an equalized received signal block {circumflex over (D)}ftnscfde.

The IFFT unit417can receive the equalized received signal block from the FDE415, can perform an IFFT algorithm to the received signal block to convert the received signal block from the frequency domain to the time domain, and can output the converted received signal block.

For example, the IFFT unit417can convert an equalized received signal block from the frequency domain into the time domain using the following equation.

Here, dftnscfdcdenotes estimated data and can be expressed as follows from the viewpoint of the ZF/MMSE equalizers.

The controller401can control overall operations of the receiver103. For example, the controller401can control the down converter403, the channel CP remover405, the FTN CP and CS adder407, the Rx matched filter409, the FTN CP and CS remover411, the FFT unit413, the FDE415, and the IFFT unit417.

For example, the controller401can down-convert a received signal block into a base band through the down converter403. The controller401can remove a channel CP from the converted received signal block through the channel CP remover405. The controller401can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder407. The controller401can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter409. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter409performing FTN.

The controller401can remove the FTN CP and CS from the FTN-applied received signal block through the FTN CP and CS remover411. The controller401can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit413. The controller401can equalize the converted frequency-domain received signal block through the FDE415. The controller401can convert the equalized received signal block from the frequency domain to the time domain through the IFFT unit417. The controller401can decode the converted time-domain received signal block to reconstruct data.

FIG. 6is a block diagram of a transmitter according to a second exemplary embodiment of the present disclosure.

Referring toFIG. 6, a transmitter101can include a controller601, a channel CP adder603, an FTN CP and CS adder605, a Tx pulse shaping filter607, an FTN CP and CS remover609, and an up converter611.

Describing each component, the channel CP adder603can receive a transmitted signal block and can add a channel CP to the transmitted signal block according to control by the controller601. For example, as illustrated inFIG. 7, the channel CP adder603can receive successive transmitted signal blocks701and703, can add a channel CP705to the transmitted signal block701, and can add a channel CP707to the transmitted signal block703. The channel CP adder603can output the channel CP-added transmitted signal block to the FTN CP and CS adder605. For example, the channel CP can be a GI between transmitted blocks, and the length of the channel CP can be determined based on the length of a CIR.

The FTN CP and CS adder605can receive the channel CP-added transmitted signal block, can add an FTN CP and CS to the transmitted signal block, and can output the FTN CP and CS-added transmitted signal block to the Tx pulse shaping filter607according to control by the controller601. For example, as illustrated inFIG. 7, the FTN CP and CS adder605can add a CP709to the front of the transmitted signal block701and can add a CS711to the rear thereof. Further, the FTN CP and CS adder605can add a CP713to the front of the transmitted signal block703and can add a CS715to the rear thereof. For example, the lengths of the CPs and CSs can be determined on the performance of the Tx pulse shaping filter607, for example, the length of a tap.

The Tx pulse shaping filter607can receive the FTN CP and CS-added transmitted signal block, can filter the transmitted signal block in a base band with a pulse-shaped filter for sampling according to FTN, and can apply FTN to the filtered transmitted signal block according to control by the controller601. For example, as illustrated inFIG. 7, the Tx pulse shaping filter607can filter the FTN CP and CS-added transmitted signal blocks701and703with a pulse-shaped filter for sampling according to FTN, thereby generating the filtered transmitted signal blocks701and703(indicated with diagonal lines). For example, the FTN CP709and CS711of the transmitted signal block701can include IBI caused by the Tx pulse shaping filter607performing FTN. The FTN CP713and CS715of the transmitted signal block703can include IBI caused by the Tx pulse shaping filter607performing FTN. The Tx pulse shaping filter607can output the FTN-applied transmitted signal block to the FTN CP and CS remover609.

The FTN CP and CS remover609can receive the FTN-applied transmitted signal block and can remove the FTN CP and CS from the received transmitted signal block according to control by the controller601. For example, as illustrated inFIG. 7, the FTN CP and CS remover609can remove the FTN CP709and CS711from the transmitted signal block701filtered with the pulse-shaped filter for sampling according to FTN and can remove the FTN CP713and CS715from the transmitted signal block703filtered with the pulse-shaped filter for sampling according to FTN. The FTN CP and CS remover609can output the FTN CP and CS-removed transmitted signal block to the up converter611.

The up converter611can receive the FTN CP and CS-removed transmitted signal block from the FTN CP and CS remover609and can modulate (for example, up-convert) the received transmitted signal block into an RF in order to transmit the transmitted signal block through the channel105according to control by the controller601.

The controller601can control overall operations of the transmitter101. For example, the controller601can control the channel CP adder603, the FTN CP and CS adder605, the Tx pulse shaping filter607, the FTN CP and CS remover609, and the up converter611.

For example, the controller601can add a channel CP to a transmitted signal block through the channel CP adder603. The controller601can add an FTN CP and CS to the channel CP-added transmitted signal block through the FTN CP and CS adder605. The controller601can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter607. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter607performing FTN.

The controller601can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FTN CP and CS remover609. The controller601can up-convert the FTN CP and CS-removed transmitted signal block into an RF through the up converter611and can transmit the transmitted signal block through the channel105.

FIG. 8is a block diagram of a receiver according to the second exemplary embodiment of the present disclosure.

Referring toFIG. 8, a receiver103can include a controller801, a down converter803, an FTN CP and CS adder805, an Rx matched filter807, an FTN CP and CS remover809, a channel CP remover811, an FFT unit813, an FDE815, and an IFFT unit817.

Describing each component, the down converter803can receive a received signal block via a receiving antenna and can down-convert the received signal block into a base band according to control by the controller801. For example, as illustrated inFIG. 9, the down converter803can receive a received signal block901with a channel CP905added and a received signal block903with a channel CP907added.

The FTN CP and CS adder805can receive the received signal block from the down converter803and can add an FTN CP and CS to the received signal block to eliminate IBI caused by the Rx matched filter807performing FTN according to control by the controller801. For example, as illustrated inFIG. 9, the FTN CP and CS adder805can add a CP909to the front of the received signal block901and can add a CS911to the rear of the received signal block901. Further, the FTN CP and CS adder805can add a CP913to the front of the received signal block903and can add a CS915to the rear of the received signal block903. The FTN CP and CS adder805can output the FTN CP and CS-added received signal block to the Rx matched filter807.

For example, the length of each of the FTN CP and CS can be determined on the performance of the Rx matched filter807, for example, the length of a tap of the Rx matched filter807. For example, the length of each of the FTN CP and CS in the receiver103can be the same as the length of each of the FTN CP and CS in the transmitter101. For another example, the length of each of the FTN CP and CS in the receiver103can be different from the length of each of the FTN CP and CS in the transmitter101.

The Rx matched filter807can receive the FTN CP and CS-added received signal block from the FTN CP and CS adder805, can filter the received signal block in a base band, and can apply FTN to the filtered received signal block according to control by the controller801. For example, the Rx matched filter807can be a squeezed sampling matched filter.

For example, as illustrated inFIG. 9, the Rx matched filter807can filter the FTN CP and CS-added received signal blocks901and903with a pulse-shaped filter for sampling according to FTN, thereby generating the filtered received signal blocks901and903(indicated with diagonal lines). For example, the FTN CP909and CS911of the received signal block901can include IBI caused by the Rx matched filter807performing FTN. The FTN CP913and CS915of the received signal block903can include IBI caused by the Rx matched filter807performing FTN. The Rx matched filter807can output the FTN-applied received signal block to the FTN CP and CS remover809.

The FTN CP and CS remover809can receive the FTN-applied received signal block from the Rx matched filter807and can remove the FTN CP and CS from the received signal block according to control by the controller801. For example, as illustrated inFIG. 9, the FTN CP and CS remover809can remove the FTN CP909and CS911from the received signal block901and can remove the FTN CP913and CS915from the received signal block903. The FTN CP and CS remover809can output the FTN CP and CS-removed received signal block to the channel CP remover811.

The channel CP remover811can receive the FTN CP and CS-removed received signal block from the FTN CP and CS remover809and can remove a channel CP from the received signal block according to control by the controller801. For example, as illustrated inFIG. 9, the channel CP remover811can remove the channel CP905from the received signal block901and can remove the channel CP907from the received signal block903. The channel CP remover811can output the channel CP-removed received signal block to the FFT unit813.

The FFT unit813can perform an FFT algorithm on the time-domain received signal block to convert the received signal block from the time domain in the frequency domain and can output the converted received signal block to the FDE815according to control by the controller801.

The FDE815can receive the frequency-domain received signal block from the FFT unit813, can equalize the received signal block in the frequency domain, and can output the equalized received signal block to the IFFT unit817according to control by the controller801. The IFFT unit817can receive the equalized received signal block from the FDE815, can perform an IFFT algorithm to the received signal block to convert the received signal block from the frequency domain to the time domain, and can output the converted received signal block according to control by the controller801.

The controller801can control overall operations of the receiver103. For example, the controller801can control the down converter803, the FTN CP and CS adder805, the Rx matched filter807, the FTN CP and CS remover809, the channel CP remover811, the FFT unit813, the FDE815, and the IFFT unit817.

For example, the controller801can down-convert a received signal block into a base band through the down converter803. The controller801can add an FTN CP and CS to the converted received signal block through the FTN CP and CS adder805. The controller801can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter807. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter807performing FTN.

The controller801can remove the FTN CP and CS from the FTN-applied received signal block through the FTN CP and CS remover809. The controller801can remove a channel CP from the received signal block through the channel CP remover811. The controller801can convert the channel CP-removed received signal block from the time domain into the frequency domain through the FFT unit813. The controller801can equalize the converted frequency-domain received signal block through the FDE815. The controller801can convert the equalized received signal block from the frequency domain into the time domain through the IFFT unit817. The controller801can decode the converted time-domain received signal block to reconstruct data.

The transmitter101illustrated inFIG. 2transmits data using FTN signaling, and the receiver103illustrated inFIG. 4equalizes data using an FDE. A single carrier (SC) transmission scheme using FTN signaling and an FDE is referred to as an FTN-SC-FDE transmission scheme.

The transmitter101illustrated inFIG. 6and the receiver103illustrated inFIG. 8are similar in structure to the transmitter101illustrated inFIG. 2and the receiver103illustrated inFIG. 4and thus are construed as following the FTN-SC-FDE transmission scheme.

FIG. 10is a block diagram of a transmitter according to a third exemplary embodiment of the present disclosure.

Referring toFIG. 10, a transmitter101can include a controller1001, an FFT unit1003, a pre-equalizer1005, an IFFT unit1007, an FTN CP and CS adder1009, a Tx pulse shaping filter1011, an FTN CP and CS remover1013, a channel CP adder1015, and an up converter1017.

Comparing with the transmitter101ofFIG. 2, the transmitter101ofFIG. 10further includes the FFT unit1003, the pre-equalizer (pre-FDE)1005, and the IFFT unit1007in addition to the structure of the transmitter101ofFIG. 2. Thus, hereinafter, the FFT unit1003, the pre-equalizer1005, and the IFFT unit1007are described in detail, while the description of the other components (the FTN CP and CS adder1009, the Tx pulse shaping filter1011, the FTN CP and CS remover1013, the channel CP adder1015, and the up converter1017) is omitted.

The FFT unit1003, the pre-FDE1005, and the IFFT unit1007are components for the transmitter101to perform pre-equalization (PE). Here, PE is for reducing the computational complexity of the receiver103as the transmitter101performs frequency-domain equalization, which the receiver103is used to perform. In particular, PE can simplify the structure of the receiver103in a down link. For example, the receiver103can be configured excluding an FDE. To perform PE, the transmitter101needs to know channel state information (CSI). For example, the transmitter101can be fed CSI back by the receiver103.

Here, a power scaling factor denotes a power scaling factor for controlling the transmission power of PE for the Tx pulse shaping filter1011of the transmitter101, the channel, and the Rx matched filter of the receiver103.

Describing each component, the FFT unit1003can receive a time-domain transmitted signal block, can perform an FFT algorithm on the transmitted signal block to convert the transmitted signal block from the time domain into the frequency domain, and can output the converted transmitted signal block to the pre-FDE1005.

For example, the FFT unit1003can generate a converted frequency-domain transmitted signal block using the following equation.

Here, Zpe−ftnscfdedenotes a converted frequency-domain transmitted signal block Ape−1denotes the inverse function of Ape. Ppedenotes a weighting matrix for PE, Ppe=Ape=Wpe. Here, Wpedenotes a weighting matrix of Ppe. Apedenotes a power scaling factor used to control the transmission power of PE for the pulse shaping filter of the transmitter101, the matched filter of the receiver103, and the channel105. The last term in Equation 19 is derived from FGrcHcGtcFH=Λα=ΛrcΛcΛtc.

For example, the transmitter101can receive the inverse function Ape−1of the power scaling factor from the receiver103and can compensate for a current power scaling factor based on the received inverse function of the power scaling factor.

The pre-FDE1005can receive the frequency-domain transmitted signal block from the FFT unit1003, can pre-equalize the transmitted signal block in the frequency domain, and can output the pre-equalized transmitted signal block to the IFFT unit1007.

For example, the pre-FDE1005can be a ZF equalizer or linear MMSE equalizer. If the pre-FDE1005is a linear MMSE equalizer, an MSE of the linear MMSE equalizer can be represented by the following equation.
MSE=[(ΛαWpe−IN)RD(ΛαWpe−IN)H]+[Rnf]  [Equation 20]

Equation 20 is derived from and {circumflex over (D)}pe−ftnscfde=Zpe−ftnscfdeand e={circumflex over (D)}pe−ftnscfde−D=(ΛαWpe−IN)D+nf.

By performing differentiation with respect to Wpe, Wpecan be acquired.
Wpe=(ΛαHΛα)−1ΛαH[Equation 21]

In addition, the power scaling factor Apecan be required such that pre-equalized average transmission power is not greater than non-pre-equalized average transmission power. For example, when E{|ApeWped|2}=E{|d|2}, Apecan be represented by the following equation.

Here, Apedenotes a power scaling factor for PE.

The IFFT unit1007can receive the pre-equalized transmitted signal block from the pre-FDE1005, can perform an IFFT algorithm to the transmitted signal block to convert the transmitted signal block from the frequency domain to the time domain, and can output the converted transmitted signal block to the FTN CP and CS adder1009.

For example, the IFFT unit1007can convert a pre-equalized transmitted signal block from the frequency domain to the time domain using the following equation.

Here, {circumflex over (d)}pe−ftnscfdedenotes time-domain estimated data (for example, a transmitted signal block). The last term in Equation 23 is derived from Grc=FHΛrcF.

The controller1001can control overall operations of the transmitter101. For example, the controller1001can control the FFT unit1003, the pre-FDE1005, the IFFT unit1007, the FTN CP and CS adder1009, the Tx pulse shaping filter1011, the FTN CP and CS remover1013, the channel CP adder1015, and the up converter1017. For example, the controller1001can pre-equalize a transmitted signal block through the FFT unit1003, the pre-FDE1005, and the IFFT unit1007. Here, pre-equalizing refers to equalization performed in advance by the transmitter101in view of loss (for example, signal power loss or the like) caused by the Tx pulse shaping filter1011of the transmitter101, the matched filter of the receiver103, and the channel105.

The controller1001can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder1009. The controller1001can filter the FTN CP and CS-added transmitted signal block and can perform FTN through the Tx pulse shaping filter1011. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter1011performing FTN. The controller1001can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover1013.

The controller1001can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder1015. The controller1001can up-convert the channel CP-added transmitted signal block into an RF through the up converter1017and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 11is a block diagram of a receiver according to the third exemplary embodiment of the present disclosure.

Referring toFIG. 11, a receiver103can include a controller1101, a down converter1103, a channel CP remover1105, an FTN CP and CS adder1107, an Rx matched filter1109, an FTN CP and CS remover1111, an FFT unit1113, a power scaling factor generator1115, and an IFFT unit1117.

The receiver103illustrated inFIG. 11is a receiver corresponding to the transmitter101ofFIG. 10. Comparing with the receiver103ofFIG. 4, the receiver103ofFIG. 11has the same structure as the receiver103ofFIG. 4except that the power scaling factor generator1115is included instead of an FDE. Thus, hereinafter, the description of the components (the down converter1103, the channel CP remover1105, the FTN CP and CS adder1107, the Rx matched filter1109, the FTN CP and CS remover1111, the FFT unit1113, and the IFFT unit1117) other than the power scaling factor generator1115is omitted.

Describing each component, the power scaling factor generator1115can receive a frequency-domain received signal block from the FFT unit1113, can determine a power scaling factor (for example, Ape−1) for PE from the received signal block, and can compensate for the signal size of the received signal block based on the determined power scaling factor. For example, the power scaling factor generator1115can determine the inverse function of the power scaling factor using pure scaling or automatic gain control (AGC).

The controller1101can control overall operations of the receiver103. For example, the controller1101can control the down converter1103, the channel CP remover1105, the FTN CP and CS adder1107, the Rx matched filter1109, the FTN CP and CS remover1111, the FFT unit1113, the power scaling factor generator1115, and the IFFT unit1117.

For example, the controller1101can down-convert a received signal block into a base band through the down converter1103. The controller1101can remove a channel CP from the converted received signal block through the channel CP remover1105. The controller1101can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder1107. The controller1101can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter1109. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter1109performing FTN.

The controller1101can remove the FTN CP and CS from the FTN-applied received signal block through FTN CP and CS remover1111. The controller1101can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit1113. The controller1101can generate a power scaling factor for PE from the frequency-domain received signal block and can compensate for the signal size of the received signal block based on the generated power scaling factor through the power scaling factor generator1115. The controller1101can convert the received signal block from the frequency domain to the time domain through the IFFT unit1117. The controller1101can decode the converted time-domain received signal block to reconstruct data.

In one exemplary embodiment, the controller1101can generate CSI and can feed the generated CSI back to the transmitter101. For example, the controller1101can feed back the CSI along with power scaling factor related information.

The transmitter101ofFIG. 10generates a transmitted signal block by performing PE and transmits the generated transmitted signal block using FTN signaling. The receiver103ofFIG. 11receives a PE-applied received signal block and reconstructs data from the received signal block. The transmission scheme applied to the transmitter101ofFIG. 10and the receiver103ofFIG. 11can be referred to as PE-FTN-SC-FDE.

FIG. 12is a block diagram of a transmitter according to a fourth exemplary embodiment of the present disclosure.

Referring toFIG. 12, a transmitter101can include a controller1201, an FFT unit1203, a pre-equalizer1205, an IFFT unit1207, an FTN CP and CS adder1209, a Tx pulse shaping filter1211, an FTN CP and CS remover1213, a channel CP adder1215, and an up converter1217.

Comparing with the transmitter101ofFIG. 10, the transmitter101ofFIG. 12includes the pre-FDE1205ofFIG. 12, instead of the pre-FDE1005ofFIG. 10. Thus, hereinafter, the pre-FDE1205is described in detail, while the description of the other components (the FFT unit1203, the IFFT unit1207, the FTN CP and CS adder1209, the Tx pulse shaping filter1211, the FTN CP and CS remover1213, the channel CP adder1215, and the up converter1217) is omitted.

Describing each component, the pre-FDE1205can receive a frequency-domain transmitted signal block from the FFT unit1203, can perform Pre-equalization for an Only Pulse shaping filter (POP) on the transmitted signal block with respect to the Tx pulse shaping filter1211of the transmitter101, and can output the pre-equalized transmitted signal block to the IFFT unit1207.

A weighting matrix Ppopfor POP can be represented by the following equation.
Ppop=Apop(ΛtcHΛtc)−1ΛtcH[Equation 24]

Here, Ppopdenotes a weighting matrix for POP, and Apop=√{square root over (N/tr{(ΛtcHΛtc)−1})} can denote a power scaling factor required to pre-equalize ISI caused by the Tx pulse shaping filter1211.

The controller1201can control overall operations of the transmitter101. For example, the controller1201can control the FFT unit1203, the pre-FDE1205, the IFFT unit1207, the FTN CP and CS adder1209, the Tx pulse shaping filter1211, the FTN CP and CS remover1213, the channel CP adder1215, and the up converter1217.

For example, the controller1201can pre-equalize a transmitted signal block through the FFT unit1203, the pre-FDE1205, and the IFFT unit1207to eliminate ISI caused by the Tx pulse shaping filter1211.

The controller1201can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder1209. The controller1201can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter1211. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter1211performing FTN. The controller1201can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover1213.

The controller1201can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder1215. The controller1201can up-convert the channel CP-added transmitted signal block into an RF through the up converter1217and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 13is a block diagram of a receiver according to the fourth exemplary embodiment of the present disclosure.

Referring toFIG. 13, a receiver103can include a controller1301, a down converter1303, a channel CP remover1305, an FTN CP and CS adder1307, an Rx matched filter1309, an FTN CP and CS remover1311, an FFT unit1313, a FDE1315, and an IFFT unit1317.

The receiver103illustrated inFIG. 13is a receiver corresponding to the transmitter101ofFIG. 12. Comparing with the receiver103ofFIG. 11, the receiver103ofFIG. 13has the same structure as the receiver103ofFIG. 11except that an FDE1315is included instead of the power scaling factor generator1115ofFIG. 11. Thus, hereinafter, the description of the components (the down converter1303, the channel CP remover1305, the FTN CP and CS adder1307, the Rx matched filter1309, the FTN CP and CS remover1311, the FFT unit1313, and the IFFT unit1317) other than the FDE1315is omitted.

Describing each component, the FDE1315can receive a time-domain received signal block from the FFT unit1313and can equalize the received signal block in view of loss (for example, signal power loss, ISI or IBI) caused by the channel105and the Rx matched filter1309of the receiver103. The FDE1315can transmit the equalized received signal block to the IFFT unit1317.

For example, the time-domain received signal block received from the FFT unit1313can be represented by the following equation.

Here, Zpop−ftnscfdedenotes a frequency-domain received signal block, which is pre-equalized in view of ISI caused by the Tx pulse shaping filter1211of the transmitter101. Apop−1denotes the inverse function of Apop. The last term in Equation 25 is derived from FGrcHcGtcFH=Λαand Λα(ΛtcHΛtc)−1ΛtcH=ΛrcΛcΛtc(ΛtcHΛtc)−1ΛtcH=ΛrcΛc=Λrx.

For example, the FDE1315can equalize the frequency-domain received signal block using the following equation.

Here, {circumflex over (D)}pop−ftnscfdedenotes equalized estimated data (for example, a received signal block), and Zpop−ftnscfdedenotes a frequency-domain received signal block. Wpopdenotes a weighting matrix for eliminating ISI caused by the channel105and the Rx matched filter1309.

If the FDE1315is a linear MMSE equalizer, an MSE of the linear MMSE equalizer can be represented as follows.
MSE=[(WpopΛrx−IN)RD(WpopΛrx−IN)H]+[WpopRnfWpopH]  [Equation 27]

By differentiating the MSE with respect to Wpop, a weighting matrix Wpopis acquired in terms of an MMSE criterion. Wpopcan be represented by the following equation.

If the FDE1315is a ZF equalizer, Wpopcan be represented by the following equation.
Wpop=Λrx†=(ΛrxHΛrx)−1ΛrxH[Equation 29]

The IFFT unit1317can receive the equalized received signal block and can convert the received signal block from the frequency domain to the time domain. For example, the IFFT unit1317can convert the equalized received signal block to the time domain using the following equation.

Here, {circumflex over (d)}pop−ftnscfdedenotes time-domain estimated data (for example, a received signal block). The last term in Equation 30 is derived from Grc=FHΛrcF.

Here, {circumflex over (d)}pop−ftnscfdedenotes time-domain estimated data (for example, a received signal block). The last term in Equation 30 is derived from Grc=FHΛrcF.

The controller1301can control overall operations of the receiver103. For example, the controller1301can control the down converter1303, the channel CP remover1305, the FTN CP and CS adder1307, the Rx matched filter1309, the FTN CP and CS remover1311, the FFT unit1313, the FDE1315, and the IFFT unit1317.

For example, the controller1301can down-convert a received signal block into a base band through the down converter1303. The controller1301can remove a channel CP from the converted received signal block through the channel CP remover1305. The controller1301can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder1307. The controller1301can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter1309. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter1309performing FTN.

The controller1301can remove the FTN CP and CS from the FTN-applied received signal block through the FTN CP and CS remover1311. The controller1301can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit1313. The controller1301can equalize the frequency-domain received signal block through the FDE1315. The controller1301can convert the equalized received signal block from the frequency domain to the time domain through the IFFT unit1317. The controller1301can decode the converted time-domain received signal block to reconstruct data.

The transmitter101ofFIG. 12pre-equalizes a transmitted signal block to eliminate ISI caused by the Tx pulse shaping filter1211and transmits the transmitted signal block using FTN signaling. The receiver103ofFIG. 13equalizes a received signal block to eliminate ISI caused by the channel105and the Rx matched filter1309.

The transmission scheme applied to the transmitter101ofFIG. 12and the receiver103ofFIG. 13can be referred to as a POP-FTN-SC-FDE transmission scheme. A POP-FTN-SC-FDE communication system can efficiently estimate data in view of a delay caused when a transmitter acquires channel information fed back from a receiver and computational complexity of the receiver in channel estimation.

FIG. 14is a block diagram of a transmitter according to a fifth exemplary embodiment of the present disclosure.

Referring toFIG. 14, a transmitter101can include a controller1401, an FFT unit1403, a pre-FDE1405, an IFFT unit1407, an FTN CP and CS adder1409, a Tx pulse shaping filter1411, an FTN CP and CS remover1413, a channel CP adder1415, and an up converter1417.

Comparing with the transmitter101ofFIG. 12, the transmitter101ofFIG. 14includes the pre-FDE1405for the channel105and the Tx pulse shaping filter1411, instead of the pre-FDE1205for the Tx pulse shaping filter1211ofFIG. 12. Thus, hereinafter, the pre-FDE1405is described in detail, while the description of the other components (the FFT unit1403, the IFFT unit1407, the FTN CP and CS adder1409, the Tx pulse shaping filter1411, the FTN CP and CS remover1413, the channel CP adder1415, and the up converter1417) is omitted.

Describing each component, the pre-FDE1405can receive a frequency-domain transmitted signal block from the FFT unit1403, can perform Pre-equalization for a Channel and Pulse shaping filter (PCP) on the transmitted signal block with respect to the channel105and the Tx pulse shaping filter1411, and can output the pre-equalized transmitted signal block to the IFFT unit1407.

For example, the pre-FDE1405can estimate ISI caused by the channel105based on CSI received from a receiver103and can determine a weighting matrix for eliminating the estimated ISI caused by the channel105and ISI caused by the Tx pulse shaping filter1411.

A weighting matrix Ppcpfor PCP can be represented by the following equation.

Here, Ppcpdenotes a weighting matrix for PCP. Apcp=√{square root over (N/tr{(ΛtxHΛtx)−1})} denotes a power scaling factor required to pre-equalize ISI from the pulse shaping filter and the channel. Λtx=ΛcΛtc.

The pre-FDE1405can pre-equalize the frequency-domain transmitted signal block based on the determined weighting matrix and can transmit the transmitted signal block to the IFFT unit1407.

The controller1401can control overall operations of the transmitter101. For example, the controller1401can control the FFT unit1403, the pre-FDE1405, the IFFT unit1407, the FTN CP and CS adder1409, the Tx pulse shaping filter1411, the FTN CP and CS remover1413, the channel CP adder1415, and the up converter1417.

For example, the controller1401can pre-equalize a transmitted signal block through the FFT unit1403, the pre-FDE1405, and the IFFT unit1407to eliminate ISI caused by the Tx pulse shaping filter1411and the channel105.

The controller1401can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder1409. The controller1401can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter1411. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter1411performing FTN. The controller1401can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover1413.

The controller1401can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder1415. The controller1401can up-convert the channel CP-added transmitted signal block into an RF through the up converter1417and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 15is a block diagram of a receiver according to the fifth exemplary embodiment of the present disclosure.

Referring toFIG. 15, a receiver103can include a controller1501, a down converter1503, a channel CP remover1505, an FTN CP and CS adder1507, an Rx matched filter1509, an FTN CP and CS remover1511, an FFT unit1513, a power scaling factor generator1515, an FDE1517, and an IFFT unit1519.

Comparing with the receiver103ofFIG. 13, the receiver103ofFIG. 15further includes the power scaling factor generator1515in addition toFIG. 13and includes the FDE1517for the Rx matched filter1507, instead of the FDE1315ofFIG. 13for the channel105and the Rx matched filter1307. Thus, hereinafter, the power scaling factor generator1515and the FDE1517are described in detail, while the description of the other components (the down converter1503, the channel CP remover1505, the FTN CP and CS adder1507, the Rx matched filter1509, the FTN CP and CS remover1511, the FFT unit1513, and the IFFT unit1519) is omitted.

According to one exemplary embodiment, the receiver103can be a receiver corresponding to the transmitter101ofFIG. 14. For example, the transmitter101ofFIG. 14can pre-equalize a transmitted signal block in view of ISI by the channel105and the Tx pulse shaping filter1411and can transmit the pre-equalized transmitted signal block according to FTN signaling. The receiver103can receive a received signal block according to FTN signaling and can equalize the received signal block, which is not pre-equalized, in view of ISI by the Rx matched filter1509to reconstruct data.

The SC transmission/reception scheme, which is used by the transmitter101ofFIG. 14and the receiver103ofFIG. 15, can be referred to as a PCP-FTN-SC-FDE transmission scheme.

Describing each component, the power scaling factor generator1515can receive a frequency-domain received signal block from the FFT unit1513and can generate a power scaling factor for the received signal block. The power scaling factor generator1515can compensate for the signal size of the frequency-domain received signal block based on the generated power scaling factor and can transmit the frequency-domain received signal block to the FDE1517.

For example, a frequency-domain received signal block according to the PCP-FTN-SC-FDE transmission scheme can be represented by the following equation.

Here, Zpcp−ftnscfdedenotes a frequency-domain received signal block, which is pre-equalized in view of ISI caused by the Tx pulse shaping filter1411of the transmitter101and the channel105. Apcp−1denotes the inverse function of a power scaling factor Apcpapplied in PE. The last term in Equation 33 is derived from FGrcHcGtcFH=Λαand Λα(ΛtxHΛtx)−1ΛtxH=ΛrcΛtx(ΛtxHΛtx)−1ΛtxH=Λrc.

For example, the power scaling factor generator1515can change the signal size of the frequency-domain received signal block based on the power scaling factor Apcp−1.

The FDE1517can receive the frequency-domain received signal block from the power scaling factor1515, can equalize the received signal block in view of ISI by the Rx matched filter1509, and can transmit the equalized received signal block to the IFFT unit1519. For example, the FDE1517can determine a weighting matrix for equalization and can equalize the frequency-domain received signal block based on the determined weighting matrix.

If the FDE1517is a linear MIVISE equalizer, the linear MIVISE equalizer can determine a weighting matrix using the following equation.

If the FDE1517is a ZF equalizer, the ZF equalizer can determine a weighting matrix using the following equation.
Wpcp=Λrc†=(ΛrcHΛrc)−1ΛrcH[Equation 35]

Here, Wpcpdenotes a weighting matrix for equalization.

For example, the FDE1517can multiply the frequency-domain received signal block by Wpcpto equalize the frequency-domain received signal block.

The IFFT unit1519can receive the equalized frequency-domain received signal block and can apply an IFFT algorithm to the frequency-domain received signal block, thereby determining a time-domain received signal block.

For example, the IFFT unit1519can determine a time-domain received signal block using the following equation.

Meanwhile, time-domain estimated data {circumflex over (d)}pcp−ftnscfdecan be expressed as follows from the viewpoint of the ZF equalizer and the linear MMSE equalizer.

The controller1501can control overall operations of the receiver103. For example, the controller1501can control the down converter1503, the channel CP remover1505, the FTN CP and CS adder1507, the Rx matched filter1509, the FTN CP and CS remover1511, the FFT unit1513, the power scaling factor generator1515, the FDE1517, and the IFFT unit1519.

For example, the controller1501can down-convert a received signal block into a base band through the down converter1503. The controller1501can remove a channel CP from the converted received signal block through the channel CP remover1505. The controller1501can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder1507. The controller1501can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter1509. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter1509performing FTN.

The controller1501can remove the FTN CP and CS from the FTN-applied received signal block through the FTN CP and CS remover1511. The controller1501can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit1513. The controller1501can compensate for the signal size of the frequency-domain received signal block through the power scaling factor generator1515. The controller1501can equalize the frequency-domain received signal block through the FDE1517. The controller1501can convert the equalized received signal block from the frequency domain to the time domain through the IFFT unit1519. The controller1501can decode the converted time-domain received signal block to reconstruct data.

FIG. 16is a block diagram of a transmitter according to a sixth exemplary embodiment of the present disclosure.

Referring toFIG. 16, a transmitter101can include a controller1601, an FFT unit1603, a subcarrier mapper1605, an IFFT unit1607, an FTN CP and CS adder1609, a Tx pulse shaping filter1611, an FTN CP and CS remover1613, a channel CP adder1615, and an up converter1617. For example, the transmitter101ofFIG. 16can be a transmitter according to an FTN signaling-based SC-Frequency Division Multiple Access (FTN-SC-FDMA) transmission scheme.

Comparing with the transmitter101ofFIG. 2, the transmitter101ofFIG. 16further includes the FFT unit1603, the subcarrier mapper1605, and the IFFT unit1607in addition to the transmitter101ofFIG. 2. Thus, hereinafter, the FFT unit1603, the subcarrier mapper1605, and the IFFT unit1607are described in detail, while the description of the other components (the FTN CP and CS adder1609, the Tx pulse shaping filter1611, the FTN CP and CS remover1613, the channel CP adder1615, and the up converter1617) is omitted.

Describing each component, the FFT unit1603can receive a time-domain transmitted signal block, can perform an FFT algorithm on the transmitted signal block to convert the transmitted signal block from the time domain into the frequency domain, and can output the converted transmitted signal block to the subcarrier mapper1605.

The subcarrier mapper1605can receive the frequency-domain transmitted signal block from the FFT unit1603, can map the transmitted signal block to a subcarrier, and can transmit the mapped transmitted signal block to the IFFT unit1607.

The IFFT unit1607can receive the subcarrier-mapped transmitted signal block from the subcarrier mapper1605, can perform an IFFT algorithm to the transmitted signal block to convert the transmitted signal block from the frequency domain to the time domain, and can transmit the converted transmitted signal block to the FTN CP and CS adder1609.

The controller1601can control overall operations of the transmitter101. For example, the controller1601can control the FFT unit1603, the subcarrier mapper1605, the IFFT unit1607, the FTN CP and CS adder1609, the Tx pulse shaping filter1611, the FTN CP and CS remover1613, the channel CP adder1615, and the up converter1617.

For example, the controller1601can map a transmitted signal block to a subcarrier through the FFT unit1603, the subcarrier mapper1605, and the IFFT unit1607. The controller1601can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder1609. The controller1601can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter1611. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter1611performing FTN. The controller1601can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover1613.

The controller1601can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder1615. The controller1601can up-convert the channel CP-added transmitted signal block into an RF through the up converter1617and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 17is a block diagram of a receiver according to the sixth exemplary embodiment of the present disclosure.

Referring toFIG. 17, a receiver103can include a controller1701, a down converter1703, a channel CP remover1705, an FTN CP and CS adder1707, an Rx matched filter1709, an FTN CP and CS remover1711, an FFT unit1713, a subcarrier demapper1715, an FDE1717, and an IFFT unit1719. For example, the receiver103ofFIG. 17can be a receiver according to the FTN-SC-FDMA transmission scheme.

The receiver103ofFIG. 17is a receiver corresponding to the transmitter101ofFIG. 16and further includes the subcarrier demapper1715in comparison with the receiver103ofFIG. 4. Thus, hereinafter, the description of the components (the controller1701, the down converter1703, the channel CP remover1705, the FTN CP and CS adder1707, the Rx matched filter1709, the FTN CP and CS remover1711, the FFT unit1713, the FDE1717, and the IFFT unit1719) other than the subcarrier demapper1715is omitted.

Describing each component, the subcarrier demapper1715can receive a frequency-domain received signal block from the FFT unit1713, can demap a subcarrier from the received signal block, and can transmit the demapped received signal block to the IFFT unit1717.

The controller1701can control overall operations of the receiver103. For example, the controller1701can control the down converter1703, the channel CP remover1705, the FTN CP and CS adder1707, the Rx matched filter1709, the FTN CP and CS remover1711, the FFT unit1713, the subcarrier demapper1715, the FDE1717, and the IFFT unit1719.

For example, the controller1701can down-convert a received signal block into a base band through the down converter1703. The controller1701can remove a channel CP from the converted received signal block through the channel CP remover1705. The controller1701can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder1707. The controller1701can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter1709. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter1709performing FTN.

The controller1701can remove the FTN CP and CS from the FTN-applied received signal block through FTN CP and CS remover1711. The controller1701can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit1713. The controller1701can demap a subcarrier from the frequency-domain received signal block through the subcarrier demapper1715. The controller1701can convert the received signal block from the frequency domain to the time domain through the IFFT unit1719. The controller1701can decode the converted time-domain received signal block to reconstruct data.

FIG. 18is a block diagram of a transmitter according to a seventh exemplary embodiment of the present disclosure.

Referring toFIG. 18, a transmitter101can include a controller1801, an FFT unit1803, a subcarrier mapper1805, a pre-FDE1807, an IFFT unit1809, an FTN CP and CS adder1811, a Tx pulse shaping filter1813, an FTN CP and CS remover1815, a channel CP adder1817, and an up converter1819.

For example, the pre-FDE1807of the transmitter101can perform PE in view of ISI caused by the channel105, the Tx pulse shaping filter1813, and the Rx matched filter of the receiver103corresponding to the Tx pulse shaping filter1813. Here, the transmitter101can be a transmitter according to a PE-FTN-SC-FDMA transmission scheme.

Comparing with the transmitter101ofFIG. 10, the transmitter101ofFIG. 18further includes a subcarrier mapper1805. Thus, hereinafter, the subcarrier mapper1805is described in detail, while the description of the other components (the FFT unit1803, the pre-FDE1807, the IFFT unit1809, the FTN CP and CS adder1811, the Tx pulse shaping filter1813, the FTN CP and CS remover1815, the channel CP adder1817, and the up converter1819) is omitted.

Describing each component, the subcarrier mapper1805can receive a frequency-domain transmitted signal block from the FFT unit1803, can map the transmitted signal block to a subcarrier, and can transmit the mapped transmitted signal block to the pre-FDE1807.

The controller1801can control overall operations of the transmitter101. For example, the controller1801can control the FFT unit1803, the subcarrier mapper1805, the pre-FDE1807, the IFFT unit1809, the FTN CP and CS adder1811, the Tx pulse shaping filter1813, the FTN CP and CS remover1815, the channel CP adder1817, and the up converter1819.

For example, the controller1801can map a frequency-domain transmitted signal block to a subcarrier and can pre-equalize the mapped transmitted signal block in view of ISI caused by the channel105, the Tx pulse shaping filter1813, and the Rx matched filter through the FFT unit1803, the pre-FDE1807, the subcarrier mapper1805, and the IFFT unit1809. The controller1801can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder1811. The controller1801can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter1813. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter1813performing FTN. The controller1801can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover1815.

The controller1801can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder1817. The controller1801can up-convert the channel CP-added transmitted signal block into an RF through the up converter1819and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 19is a block diagram of a receiver according to the seventh exemplary embodiment of the present disclosure.

Referring toFIG. 19, a receiver103can include a controller1901, a down converter1903, a channel CP remover1905, an FTN CP and CS adder1907, an Rx matched filter1909, an FTN CP and CS remover1911, an FFT unit1913, a power scaling factor generator1915, a subcarrier demapper1917, and an IFFT unit1919.

For example, when the receiver103is a receiver corresponding to the transmitter101ofFIG. 18, the receiver103can be a receiver according to the PE-FDE-SC-FDMA transmission scheme.

Comparing with the receiver103ofFIG. 11, the receiver103ofFIG. 19further includes the subcarrier demapper1917. Thus, hereinafter, the description of the components (the down converter1903, the channel CP remover1905, the FTN CP and CS adder1907, the Rx matched filter1909, the FTN CP and CS remover1911, the FFT unit1913, the power scaling factor generator1915, and the IFFT unit1919) other than the subcarrier demapper1917is omitted.

Describing each component, the subcarrier demapper1917can receive a received signal block with a compensated signal size from the power scaling factor generator1915, can demap a subcarrier from the received signal block, and can transmit the demapped received signal block to the IFFT unit1919.

The controller1901can control overall operations of the receiver103. For example, the controller1901can control the down converter1903, the channel CP remover1905, the FTN CP and CS adder1907, the Rx matched filter1909, the FTN CP and CS remover1911, the FFT unit1913, the power scaling factor generator1915, the subcarrier demapper1917, and the IFFT unit1919.

For example, the controller1901can down-convert a received signal block into a base band through the down converter1903. The controller1901can remove a channel CP from the converted received signal block through the channel CP remover1905. The controller1901can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder1907. The controller1901can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter1909. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter1909performing FTN.

The controller1901can remove the FTN CP and CS from the FTN-applied received signal block through FTN CP and CS remover1911. The controller1901can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit1913. The controller1901can generate a power scaling factor for the frequency-domain received signal block and can compensate for the signal size of the received signal block based on the generated power scaling factor through the power scaling factor generator1915. The controller1901can demap a subcarrier from the compensated received signal block through the subcarrier demapper1917. The controller1901can convert the demapped received signal block from the frequency domain to the time domain through the IFFT unit1919. The controller1901can decode the converted time-domain received signal block to reconstruct data.

In one exemplary embodiment, the controller1901can generate CSI and can feed the generated CSI back to the transmitter101.

FIG. 20is a block diagram of a transmitter according to an eighth exemplary embodiment of the present disclosure.

Referring toFIG. 20, a transmitter101can include a controller2001, an FFT unit2003, a pre-FDE2007, a subcarrier mapper2005, an IFFT unit2009, an FTN CP and CS adder2011, a Tx pulse shaping filter2013, an FTN CP and CS remover2015, a channel CP adder2017, and an up converter2019.

For example, the pre-FDE2007of the transmitter101can perform PE in view of only ISI caused by the Tx pulse shaping filter2013. Here, the transmitter101can be referred to as a transmitter according to a POP-FTN-SC-FDMA transmission scheme.

Comparing with the transmitter101ofFIG. 12, the transmitter101ofFIG. 20further includes the subcarrier mapper2005. Thus, hereinafter, the subcarrier mapper2005is described in detail, while the description of the other components (the FFT unit2003, the pre-FDE2007, the IFFT unit2009, the FTN CP and CS adder2011, the Tx pulse shaping filter2013, the FTN CP and CS remover2015, the channel CP adder2017, and the up converter2019) is omitted.

Describing each component, the subcarrier mapper2005can receive a frequency-domain transmitted signal block from the FFT unit2003, can map the transmitted signal block to a subcarrier, and can transmit the mapped transmitted signal block to the pre-FDE2007.

The controller2001can control overall operations of the transmitter101. For example, the controller2001can control the FFT unit2003, the pre-FDE2007, the subcarrier mapper2005, the IFFT unit2009, the FTN CP and CS adder2011, the Tx pulse shaping filter2013, the FTN CP and CS remover2015, the channel CP adder2017, and the up converter2019.

For example, the controller2001can map a frequency-domain transmitted signal block to a subcarrier and can pre-equalize the mapped transmitted signal block in view of ISI caused by the Tx pulse shaping filter2013through the FFT unit2003, the pre-FDE2007, the subcarrier mapper2005, and the IFFT unit2009. The controller2001can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder2011. The controller2001can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter2013. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter2013performing FTN. The controller2001can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover2015.

The controller2001can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder2017. The controller2001can up-convert the channel CP-added transmitted signal block into an RF through the up converter2019and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 21is a block diagram of a receiver according to the eighth exemplary embodiment of the present disclosure.

Referring toFIG. 21, a receiver103can include a controller2101, a down converter2103, a channel CP remover2105, an FTN CP and CS adder2107, an Rx matched filter2109, an FTN CP and CS remover2111, an FFT unit2113, a power scaling factor generator2115, an FDE2117, a subcarrier demapper2119and an IFFT unit2121.

For example, when the receiver103is a receiver corresponding to the transmitter101ofFIG. 20, the receiver103can be referred to as a receiver according to the POP-FDE-SC-FDMA transmission scheme.

Comparing with the receiver103ofFIG. 13, the receiver103ofFIG. 21further includes the subcarrier demapper2119. Thus, hereinafter, the description of the components (the down converter2103, the channel CP remover2105, the FTN CP and CS adder2107, the Rx matched filter2109, the FTN CP and CS remover2111, the FFT unit2113, the power scaling factor generator2115, the FDE2117, and the IFFT unit2121) other than the subcarrier demapper2119is omitted.

Describing each component, the subcarrier demapper2119can receive an equalized frequency-domain received signal block from the FDE2117, can demap a subcarrier from the received signal block, and can transmit the demapped received signal block to the IFFT unit2121.

The controller2101can control overall operations of the receiver103. For example, the controller2101can control the down converter2103, the channel CP remover2105, the FTN CP and CS adder2107, the Rx matched filter2109, the FTN CP and CS remover2111, the FFT unit2113, the power scaling factor generator2115, the subcarrier demapper2119, the FDE2117, and the IFFT unit2121.

For example, the controller2101can down-convert a received signal block into a base band through the down converter2103. The controller2101can remove a channel CP from the converted received signal block through the channel CP remover2105. The controller2101can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder2107. The controller2101can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter2109. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter2109performing FTN.

The controller2101can remove the FTN CP and CS from the FTN-applied received signal block through FTN CP and CS remover2111. The controller2101can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit2113. The controller2101can generate a power scaling factor for the frequency-domain received signal block and can compensate for the signal size of the received signal block based on the generated power scaling factor through the power scaling factor generator2115. The controller2101can equalize the received signal block in view of ISI caused by the channel105and the Rx matched filter2109through the FDE2117. The controller2101can demap a subcarrier from the equalized received signal block through the subcarrier demapper2119. The controller2101can convert the demapped received signal block from the frequency domain to the time domain through the IFFT unit2121. The controller2101can decode the converted time-domain received signal block to reconstruct data.

FIG. 22is a block diagram of a transmitter according to a ninth exemplary embodiment of the present disclosure.

Referring toFIG. 22, a transmitter101can include a controller2201, an FFT unit2203, a pre-FDE2207, a subcarrier mapper2205, an IFFT unit2209, an FTN CP and CS adder2211, a Tx pulse shaping filter2213, an FTN CP and CS remover2215, a channel CP adder2217, and an up converter2219.

For example, the pre-FDE2207of the transmitter101can perform PE in view of ISI caused by the Tx pulse shaping filter2213and the channel105. Here, the transmitter101can be referred to as a transmitter according to a PCP-FTN-SC-FDMA transmission scheme.

Comparing with the transmitter101ofFIG. 14, the transmitter101ofFIG. 22further includes the subcarrier mapper2205. Thus, hereinafter, the subcarrier mapper2205is described in detail, while the description of the other components (the FFT unit2203, the pre-FDE2207, the IFFT unit2209, the FTN CP and CS adder2211, the Tx pulse shaping filter2213, the FTN CP and CS remover2215, the channel CP adder2217, and the up converter2219) is omitted.

Describing each component, the subcarrier mapper2205can receive a frequency-domain transmitted signal block from the FFT unit2203, can map the transmitted signal block to a subcarrier, and can transmit the mapped transmitted signal block to the pre-FDE2207.

The controller2201can control overall operations of the transmitter101. For example, the controller2201can control the FFT unit2203, the pre-FDE2207, the subcarrier mapper2205, the IFFT unit2209, the FTN CP and CS adder2211, the Tx pulse shaping filter2213, the FTN CP and CS remover2215, the channel CP adder2217, and the up converter2219.

For example, the controller2201can map a frequency-domain transmitted signal block to a subcarrier and can pre-equalize the mapped transmitted signal block in view of ISI caused by the channel105and the Tx pulse shaping filter2213through the FFT unit2203, the pre-FDE2207, the subcarrier mapper2205, and the IFFT unit2209. The controller2201can add an FTN CP and CS to the transmitted signal block through the FTN CP and CS adder2211. The controller2201can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Tx pulse shaping filter2213. Here, the FTN CP and CS of the FTN-applied transmitted signal block can include IBI caused by the Tx pulse shaping filter2213performing FTN. The controller2201can remove the FTN CP and CS from the FTN-applied transmitted signal block through the FIN CP and CS remover2215.

The controller2201can add a channel CP to the FTN CP and CS-removed transmitted signal block through the channel CP adder2217. The controller2201can up-convert the channel CP-added transmitted signal block into an RF through the up converter2219and can transmit the transmitted signal block to the receiver103through the channel105.

FIG. 23is a block diagram of a receiver according to the ninth exemplary embodiment of the present disclosure.

Referring toFIG. 23, a receiver103can include a controller2301, a down converter2303, a channel CP remover2305, an FTN CP and CS adder2307, an Rx matched filter2309, an FTN CP and CS remover2311, an FFT unit2313, a power scaling factor generator2315, a subcarrier demapper2317, an FDE2319, and an IFFT unit2321.

For example, when the receiver103is a receiver corresponding to the transmitter101ofFIG. 22, the receiver103can be referred to as a receiver according to the PCP-FDE-SC-FDMA transmission scheme.

Comparing with the receiver103ofFIG. 15, the receiver103ofFIG. 23further includes the subcarrier demapper2317. Thus, hereinafter, the description of the components (for example, the down converter2303, the channel CP remover2305, the FTN CP and CS adder2307, the Rx matched filter2309, the FTN CP and CS remover2311, the FFT unit2313, the power scaling factor generator2315, the FDE2319, and the IFFT unit2321) other than the subcarrier demapper2317is omitted.

Describing each component, the subcarrier demapper2317can receive a received signal block with a compensated signal size from the power scaling factor generator2315, can demap a subcarrier from the received signal block, and can transmit the demapped received signal block to the FDE2319.

The controller2301can control overall operations of the receiver103. For example, the controller2301can control the down converter2303, the channel CP remover2305, the FTN CP and CS adder2307, the Rx matched filter2309, the FTN CP and CS remover2311, the FFT unit2313, the power scaling factor generator2315, the subcarrier demapper2317, the FDE2319, and the IFFT unit2321.

For example, the controller2301can down-convert a received signal block into a base band through the down converter2303. The controller2301can remove a channel CP from the converted received signal block through the channel CP remover2305. The controller2301can add an FTN CP and CS to the channel CP-removed received signal block through the FTN CP and CS adder2307. The controller2301can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN and can perform FTN through the Rx matched filter2309. Here, the FTN CP and CS of the FTN-applied received signal block can include IBI caused by the Rx matched filter2309performing FTN.

The controller2301can remove the FTN CP and CS from the FTN-applied received signal block through FTN CP and CS remover2311. The controller2301can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain through the FFT unit2313. The controller2301can generate a power scaling factor for the frequency-domain received signal block and can compensate for the signal size of the received signal block based on the generated power scaling factor through the power scaling factor generator2315. The controller2301can demap a subcarrier from the compensated received signal block through the subcarrier demapper2317. The controller2301can equalize the demapped received signal block in view of ISI caused by the Rx matched filter2309through the FDE2319. The controller2301can convert the equalized received signal block from the frequency domain to the time domain through the IFFT unit2321. The controller2301can decode the converted time-domain received signal block to reconstruct data.

FIG. 24is a flowchart illustrating that the transmitter according to the first exemplary embodiment of the present disclosure transmits data. For example, the transmitter101can be a transmitter according to an FTN-SC-FDE or FTN-SC-FDMA transmission scheme.

Referring toFIG. 24, the controller201(or controller1601) can add an FTN CP and CS to a transmitted signal block in operation2401, and can proceed to operation2403. For example, the controller201can add the FTN CP and CS to the transmitted signal block using Equation 1. For example, the length of each of the CP and CS can be determined on the performance of the Tx pulse shaping filter205(or1611) of the transmitter101. Alternatively, the length of each of the CP and CS can be determined on the length of a tap of the Tx pulse shaping filter205.

The controller201can filter the FTN CP and CS-added transmitted signal block with a pulse-shaped filter for sampling according to FTN in view of FTN signaling through the Tx pulse shaping filter205in operation2403, and can proceed to operation2405. For example, the controller201can apply FTN to the FTN CP and CS-added transmitted signal block using Equation 2. For example, the FTN CP and CS after filtering can include IBI caused by the Tx pulse shaping filter205.

The controller201can remove the FTN CP and CS from the transmitted signal block, which is filtered with the pulse-shaped filter for sampling according to FTN, in operation2405, and can proceed to operation2407. For example, the controller201can remove, using Equation 3, the FTN CP and CS from the transmitted signal block, which is filtered with the pulse-shaped filter for sampling according to FTN.

The controller201can add a channel CP to the FTN CP and CS-removed transmitted signal block in operation2407, and can proceed to operation2409. Here, the channel CP is a GI for preventing IBI caused by the channel105. For example, the controller201can add the channel CP to the FTN CP and CS-removed transmitted signal block using Equation 4. For example, the length of the channel CP can be determined based on a channel characteristic. Alternative, the length of the channel CP can be can be determined based on the length of a CIR.

In operation2409, the controller201can transmit the channel CP-added transmitted signal block. For example the controller201can up-convert the channel CP-added transmitted signal block into an RF and can transmit the transmitted signal block through the channel105.

FIG. 25is a flowchart illustrating that the receiver according to the first exemplary embodiment of the present disclosure receives data. For example, the receiver103can be a receiver according to the FTN-SC-FDE or FTN-SC-FDMA transmission scheme.

Referring toFIG. 25, the controller401(or controller1701) can remove a channel CP from a received signal block received through the channel105in operation2501, and can proceed to operation2503. For example, the controller401can receive the received signal block through the channel105and can down-convert the received signal block from an ultrahigh frequency to a base band. For example, the ultrahigh frequency can be a frequency of 3 to 60 GHz. For example, the controller401can remove the channel CP from the received signal block using Equation 7.

The controller401can add an FTN CP and CS to the channel CP-removed received signal block in operation2503, and can proceed to operation2505. For example, the controller401can add the FTN CP and CS to the channel CP-removed received signal block using Equation 8. For example, the length of each of the FTN CP and CS can be determined based on the performance of the Rx matched filter409(or1709). Alternatively, the length of each of the FTN CP and CS can be determined based on the length of a tap of the Rx matched filter409(or1709). Alternatively, the length of each of the FTN CP and CS can be can be the same as, or different from, the length of each of the FTN CP and CS added to the transmitted signal block in the transmitter101.

The controller401can filter the FTN CP and CS-added received signal block with a pulse-shaped filter for sampling according to FTN in view of FTN signaling through the Rx matched filter409in operation2505, and can proceed to operation2507. For example, the controller401can apply FTN to the FTN CP and CS-added received signal block using Equation 9. For example, the FTN CP and CS after filtering can include IBI caused by the Rx matched filter409.

The controller401can remove the FTN CP and CS from the filtered received signal block in operation2507, and can proceed to operation2509. For example, the controller401can remove the FTN CP and CS from the filtered received signal block using Equation 10.

The controller401can convert the FTN CP and CS-removed received signal block from the time domain to the frequency domain in operation2509, and can proceed to operation2511. For example, the controller401can apply a DFT or FFT algorithm to the FTN CP and CS-removed received signal block, thereby converting the received signal block from the time domain to the frequency domain. For example, the frequency-domain received signal block can be represented by Equation 13.

The controller401can equalize the converted received signal block in operation2511, and can proceed to operation2513. For example, the controller401can equalize the received signal block to eliminate ISI caused by the channel105, the Tx pulse shaping filter205, and the Rx matched filter409.

The controller401can convert the equalized received signal block from the frequency domain to the time domain in operation2513, and can proceed to operation2515. For example, the controller401can apply an IDFT or IFFT algorithm to the equalized received signal block, thereby converting the equalized received signal block from the frequency domain to the time domain. For example, the controller401can convert the equalized received signal block from the frequency domain to the time domain using Equation 17. For example, the time-domain received signal block can be estimated data.

In operation2515, the controller401can decode the converted time-domain received signal block to reconstruct data.

FIG. 26is a flowchart illustrating that the transmitter according to the third exemplary embodiment of the present disclosure transmits data. For example, the transmitter101can be a transmitter according to a PE-FTN-SC-FDE or PE-FTN-SC-FDMA transmission scheme.

Referring toFIG. 26, the controller1001(or1801) can pre-equalize a transmitted signal block to prevent ISI by the channel105, the Tx pulse shaping filter1011(or1813), and the Rx matched filter1109(or1909) corresponding to the Tx pulse shaping filter1011in operation2601, and can proceed to operation2603.

The controller1001can add an FTN CP and CS to the pre-equalized transmitted signal block in operation2603, and can proceed to operation2605. For example, the controller1001can add the FTN CP and CS to the transmitted signal block using Equation 1. For example, the length of each of the CP and CS can be determined based on the performance of the Tx pulse shaping filter1011(or1813). Alternatively, the length of each of the CP and CS can be determined based on the length of a tap of the Tx pulse shaping filter1011.

FIG. 27is a flowchart illustrating that the receiver according to the third exemplary embodiment of the present disclosure receives data. For example, the receiver103can be a receiver according to the PE-FTN-SC-FDE or PE-FTN-SC-FDMA transmission scheme.

Referring toFIG. 27, the controller1101(or1901) can sequentially perform operations2701to2707. Since operations2701to2707correspond to operations2501to2507ofFIG. 25, respectively, a detailed description of operations2701to2707is omitted.

The controller1101can convert an FTN CP and CS-removed received signal block from the time domain to the frequency domain in operation2709, and can proceed to operation2711. For example, the controller1101can apply a DFT or FFT algorithm to the FTN CP and CS-removed received signal block, thereby converting the received signal block from the time domain to the frequency domain. For example, the frequency-domain received signal block can be a received signal block that is pre-equalized to prevent ISI by the channel105, the Tx pulse shaping filter1011(or1813), and the Rx matched filter1109(or1909). For example, the frequency-domain received signal block can be represented by Equation 19. For example, the controller1101can generate CSI for the frequency-domain received signal block and can feed the generated CSI back to the transmitter101.

The controller1101can compensate for the signal size of the converted frequency-domain received signal block in operation2711, and can proceed to operation2713. For example, the controller1101can determine a power scaling factor for the converted received signal block and can amplify the converted received signal block based on the determined power scaling factor.

The controller1101can convert the received signal block from the frequency domain to the time domain in operation2713, and can proceed to operation2715. For example, the controller1101can apply an IDFT or IFFT algorithm to the received signal block, thereby converting the received signal block from the frequency domain to the time domain. For example, the controller1101can convert the equalized received signal block from the frequency domain to the time domain using Equation 23. For example, the time-domain received signal block can be estimated data.

In operation2715, the controller1101can decode the converted time-domain received signal block to reconstruct data.

FIG. 28is a flowchart illustrating that the transmitter according to the fourth exemplary embodiment of the present disclosure transmits data. For example, the transmitter101can be a transmitter according to an POP-FTN-SC-FDE or POP-FTN-SC-FDMA transmission scheme.

Referring toFIG. 28, the controller1201(or2001) can pre-equalize a transmitted signal block to prevent ISI by the Tx pulse shaping filter1211(or2013) in operation2801, and can proceed to operation2803.

The controller1201can add an FTN CP and CS to the pre-equalized transmitted signal block in operation2803, and can proceed to operation2805. For example, the controller1201can add the FTN CP and CS to the transmitted signal block using Equation 1. For example, the length of each of the CP and CS can be determined based on the performance of the Tx pulse shaping filter1211(or2013). Alternatively, the length of each of the CP and CS can be determined based on the length of a tap of the Tx pulse shaping filter1211.

FIG. 29is a flowchart illustrating that the receiver according to the fourth exemplary embodiment of the present disclosure receives data. For example, the receiver103can be a receiver according to the POP-FTN-SC-FDE or POP-FTN-SC-FDMA transmission scheme.

Referring toFIG. 29, the controller1301(or2101) can sequentially perform operations2901to2907. Since operations2901to2907correspond to operations2501to2507ofFIG. 25, respectively, a detailed description of operations2901to2907is omitted.

The controller1301can convert an FTN CP and CS-removed received signal block from the time domain to the frequency domain in operation2909, and can proceed to operation2911. For example, the controller1301can apply a DFT or FFT algorithm to the FTN CP and CS-removed received signal block, thereby converting the received signal block from the time domain to the frequency domain. For example, the frequency-domain received signal block can be a received signal block that is pre-equalized to prevent ISI by the Tx pulse shaping filter1211(or2013). For example, the frequency-domain received signal block can be represented by Equation 25.

The controller1301can equalize the converted received signal block in operation2911, and can proceed to operation2913. For example, the controller1301can equalize the received signal block to eliminate ISI caused by the channel105and the Rx matched filter1309(or2109). Here, since the converted received signal block is pre-equalized to prevent ISI by the Tx pulse shaping filter1211, the controller1301can equalize the received signal block without considering ISI by the Tx pulse shaping filter1211.

The controller1301can convert the equalized received signal block from the frequency domain to the time domain in operation2913, and can proceed to operation2915. For example, the controller1301can apply an IDFT or IFFT algorithm to the received signal block, thereby converting the received signal block from the frequency domain to the time domain. For example, the controller1301can convert the equalized received signal block from the frequency domain to the time domain using Equation 30. For example, the time-domain received signal block can be estimated data.

In operation2915, the controller1301can decode the converted time-domain received signal block to reconstruct data.

FIG. 30is a flowchart illustrating that the transmitter according to the fifth exemplary embodiment of the present disclosure transmits data. For example, the transmitter101can be a transmitter according to an PCP-FTN-SC-FDE or PCP-FTN-SC-FDMA transmission scheme.

Referring toFIG. 30, the controller1401(or2201) can pre-equalize a transmitted signal block to prevent ISI by the channel105and the Tx pulse shaping filter1411(or2213) in operation3001, and can proceed to operation3003.

The controller1401can add an FTN CP and CS to the pre-equalized transmitted signal block in operation3003, and can proceed to operation3005. For example, the controller1401can add the FTN CP and CS to the transmitted signal block using Equation 1. For example, the length of each of the CP and CS can be determined based on the performance of the Tx pulse shaping filter1411(or2213). Alternatively, the length of each of the CP and CS can be determined based on the length of a tap of the Tx pulse shaping filter1411.

FIG. 31is a flowchart illustrating that the receiver according to the fifth exemplary embodiment of the present disclosure receives data. For example, the receiver103can be a receiver according to the PCP-FTN-SC-FDE or PCP-FTN-SC-FDMA transmission scheme.

Referring toFIG. 31, the controller1501(or2301) can sequentially perform operations3101to3107. Since operations3101to3107correspond to operations2501to2507ofFIG. 25, respectively, a detailed description of operations3101to3107is omitted.

The controller1501can convert an FTN CP and CS-removed received signal block from the time domain to the frequency domain in operation3109, and can proceed to operation3111. For example, the controller1501can apply a DFT or FFT algorithm to the FTN CP and CS-removed received signal block, thereby converting the received signal block from the time domain to the frequency domain. For example, the frequency-domain received signal block can be a received signal block that is pre-equalized to prevent ISI by the channel105and the Tx pulse shaping filter1411(or2113). For example, the frequency-domain received signal block can be represented by Equation 33.

The controller1501can compensate for the signal size of the converted frequency-domain received signal block in operation3111, and can proceed to operation3113. For example, the controller1501can determine a power scaling factor for the converted received signal block and can amplify the converted received signal block based on the determined power scaling factor.

The controller1501can equalize the converted received signal block in operation3113, and can proceed to operation3115. For example, the controller1501can equalize the received signal block to eliminate ISI caused by the Rx matched filter1509(or2309). Here, since the converted received signal block is pre-equalized to prevent ISI by the channel105and the Tx pulse shaping filter1411, the controller1501can equalize the received signal block without considering ISI by the channel105and the Tx pulse shaping filter1411.

The controller1501can convert the equalized received signal block from the frequency domain to the time domain in operation3115, and can proceed to operation3117. For example, the controller1501can apply an IDFT or IFFT algorithm to the received signal block, thereby converting the received signal block from the frequency domain to the time domain. For example, the controller1501can convert the equalized received signal block from the frequency domain to the time domain using Equation 36. For example, the time-domain received signal block can be estimated data.

In operation3117, the controller1501can decode the converted time-domain received signal block to reconstruct data.

According to one exemplary embodiment of the present disclosure, the positions of the pre-FDEs and the subcarrier mappers that are included in the transmitters can be switched with each other. According to one exemplary embodiment of the present disclosure, the positions of the subcarrier demappers and the FDEs that are included in the receivers can be switched with each other according to the positions of the pre-FDEs and the subcarrier mappers that are included in the transmitters. According to one exemplary embodiment of the present disclosure, although the transmitters and the receivers are illustrated as including one antenna, the transmitters and the receivers can include a plurality of antennas. Thus, the present description can be employed for diverse operations through a plurality of antennas, for example, an MIMO operation.

An exemplary embodiment of the present disclosure can eliminate IBI from a block using addition and removal of symbols.

Another exemplary embodiment of the present disclosure can equalize a block in view of both ISI caused by FTN and ISI caused by a channel, thereby reducing the computational complexity of a receiver.

Further, still another exemplary embodiment of the present disclosure can transmit a block via PE in view of ISI, thereby reducing the computational complexity of a receiver.

In addition yet another exemplary embodiment of the present disclosure may allow a transmitter to pre-equalize a block in view of ISI and may allow a receiver to additionally equalize the block in view of remaining ISI, thereby reducing the computational complexity of the receiver.