The present invention relates to a method of improving the performance in bandwidth constrained communication systems while reducing the complexity of the equalizer used for information retrieval, as well as to improving the capacity of communication systems. The said properties are achieved by appropriate information encoding, prior to signal shaping before transmission, whereas the equalizer complexity is reduced by applying the intersymbol interference shortening filter prior to the information retrieving equalization. A proper combination of the recounted elements is capable of providing a qualitatively improved and previously unsuspected performance, as compared to its constituent elements.

An inter-carrier interference (ICI) mitigation circuit associated with an orthogonal frequency division multiplexing (OFDM) receiver is disclosed. The ICI mitigation circuit comprises an ICI cancellation circuit configured to receive an OFDM symbol associated with an OFDM signal and determine an ICI associated with one or more OFDM subcarriers within the OFDM symbol. The ICI cancellation circuit is further configured to cancel the ICI from the one or more OFDM subcarriers associated with the OFDM symbol, in order to generate a desired OFDM symbol. In some embodiments, the ICI is determined and cancelled at the ICI cancellation circuit, in accordance with a predetermined ICI mitigation algorithm.

The present disclosure relates to a pre-5.sup.th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4.sup.th-Generation (4G) communication system such as Long Term Evolution (LTE). A method and an apparatus for channel estimation in a wireless communication system are provided. According to various embodiments of the present disclosure, an method of a receiving apparatus in a wireless communication system includes: estimating channel tap values by using a first reference signal; and estimating an effective channel regarding a second reference signal, based on channel tap indexes corresponding to values greater than or equal to a threshold from among the channel tap values. According to various embodiments of the present disclosure, the receiving apparatus can more exactly estimate an effective channel, and can achieve a lower BLER even in a high SNR region.

An echo detection circuit for a multi-carrier system includes a memory, a threshold generating circuit and an echo determining circuit. The memory stores a plurality of channel impulse response values of the multi-channel system. The channel impulse response values include a target channel impulse response value, a plurality of preceding channel impulse response values and a plurality of subsequent channel impulse response values; a threshold generating circuit, coupled to the memory, generating a threshold corresponding to the target channel impulse response according to the preceding channel impulse response values and the subsequent channel impulse response values; and an echo determining circuit, coupled to the threshold generating circuit and the memory, comparing the target channel impulse response value with the threshold to determine whether the target channel impulse response value corresponds to an echo path of the multi-carrier system.

Methods and systems are provided for adaptive guard interval (GI) combining. When a signal carrying at least one symbol that is preceded by a guard interval that comprises a portion of the symbol is received, a portion of the guard interval that is free from inter-symbol interference (ISI) may be determined, and only a part of the ISI-free portion of the guard interval may be extracted. The part of the ISI-free portion of the guard interval may be selected based on timing adjustment, relative to start of the symbol, that is applied to a function used in extracting the symbol. The extracted part of the ISI-free portion of the guard interval may then be combined with a corresponding portion of the symbol. The extracting and/or combining may be performed after a determination that a delay spread is smaller than a predetermined channel delay.

Precoding, a symbol permutation operation, or pulse shaping may be used to suppress or cancel a tail or head of a symbol. Precoding may include utilization of a suppression vector. A unique word (UW) may be added to the suppression vector before spreading. The symbol and values of the suppression vector may be spread by a spreading function(s) and may be shaped prior to transmission.

The present invention relates to a method of improving the performance in bandwidth constrained communication systems while reducing the complexity of the equalizer used for information retrieval, as well as to improving the capacity of communication systems. The said properties are achieved by appropriate information encoding, prior to signal shaping before transmission, whereas the equalizer complexity is reduced by applying the intersymbol interference shortening filter prior to the information retrieving equalization. A proper combination of the recounted elements is capable of providing a qualitatively improved and previously unsuspected performance, as compared to its constituent elements.

Certain aspects of the present disclosure relate to techniques for estimating a channel using soft-windowing. A user equipment (UE) may determine, based on a cyclic prefix (CP) length of a channel, a timing window for sampling reference signals transmitted on the channel, determine a set of weights to apply to samples obtained within the determined timing window, wherein each weight corresponds to a sample obtained within the determined window, and estimate the channel by applying the weights to the samples.

The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate than a 4G communication system such as LTE. The present disclosure relates to a method for a transmission end to estimate a channel in a communication system supporting multiple input multiple output (MIMO)-based beamforming, the method comprising: a step of obtaining a candidate channel estimate of each of a plurality of candidate beam combinations by means of a channel estimation section corresponding to each of the plurality of candidate beam combinations, the combinations consisting of at least one transmission beam and at least one reception beam from among transmission beams of the transmission end and reception beams of a reception end, wherein the channel estimation section corresponding to each of the plurality of candidate beam combinations comprises a serving channel estimation section corresponding to a serving beam combination of the transmission end and the reception end, a channel gain estimation section of one candidate beam combination of the plurality of candidate beam combinations, and a channel estimation section of the candidate beam combination; and a step of obtaining an optimal channel estimation value of the transmission end and the reception end on the basis of the obtained candidate channel estimates.

An echo detection circuit for a multi-carrier system includes a memory, a threshold generating circuit and an echo determining circuit. The memory stores a plurality of channel impulse response values of the multi-channel system. The channel impulse response values include a target channel impulse response value, a plurality of preceding channel impulse response values and a plurality of subsequent channel impulse response values; a threshold generating circuit, coupled to the memory, generating a threshold corresponding to the target channel impulse response according to the preceding channel impulse response values and the subsequent channel impulse response values; and an echo determining circuit, coupled to the threshold generating circuit and the memory, comparing the target channel impulse response value with the threshold to determine whether the target channel impulse response value corresponds to an echo path of the multi-carrier system.