Abstract: A method of an RFC chip for a station, the RFC chip including a WLAN communication module to decode a DL MU-MIMO wireless signal, the method including: determining an FS layer column based on a product of a channel matrix of the station and an estimate of a steering matrix of the station; ordering columns of a sub-matrix of an effective channel matrix of the station to determine one or more SS layer columns from the sub-matrix, the sub-matrix being determined by removing, from the effective channel matrix, a column corresponding to the determined FS layer column; configuring a modified effective channel matrix based on the determined FS layer column and the ordered columns of the sub-matrix, the determined FS layer column being determined as an FS layer column of the modified effective channel matrix; and determining a symbol of the station based on the modified effective channel matrix.

Abstract: A method of canceling interference by a signal receiving apparatus in a communication system supporting a multi-user Multiple-Input Multiple-Output (MIMO) scheme and a signal receiving apparatus is provided. The method includes determining whether there is a need for using an interference cancellation scheme while performing a signal detecting operation; and performing the signal detecting operation using the interference cancellation scheme, or performing the signal detecting operation without using the interference cancellation scheme based on determining whether there is the need for using the interference cancellation scheme.

Abstract: A method of an RFC chip for a station, the RFC chip including a WLAN communication module to decode a DL MU-MIMO wireless signal, the method including: determining an FS layer column based on a product of a channel matrix of the station and an estimate of a steering matrix of the station; ordering columns of a sub-matrix of an effective channel matrix of the station to determine one or more SS layer columns from the sub-matrix, the sub-matrix being determined by removing, from the effective channel matrix, a column corresponding to the determined FS layer column; configuring a modified effective channel matrix based on the determined FS layer column and the ordered columns of the sub-matrix, the determined FS layer column being determined as an FS layer column of the modified effective channel matrix; and determining a symbol of the station based on the modified effective channel matrix.

Abstract: A method of controlling a data rate by a transmitting device in a wireless communication system and the transmitting device are provided. The method includes detecting a condition to change a current data rate; performing a probing process based on a bandwidth and a Modulation and Coding Scheme (MCS); and controlling the data rate based on a result of the probing process. The transmitting device includes a controller configured to detect a condition to change a current data rate; and a transmitter and a receiver configured to perform a probing process based on a bandwidth and an MCS, wherein the controller is further configured to control a data rate based on a result of the probing process.

Abstract: A method of operating a wireless local area network (WLAN) system is provided. The WLAN includes an access point supporting uplink multiple user multiple input multiple output mode. The method of operating the WLAN system includes selecting a first station, receiving channel information from the selected first station by a second station, calculating a SNR reduction value based on the channel information by the second station, and selecting the second station based on the SNR reduction value.

Abstract: A method of canceling interference by a signal receiving apparatus in a communication system supporting a multi-user Multiple-Input Multiple-Output (MIMO) scheme and a signal receiving apparatus is provided. The method includes determining whether there is a need for using an interference cancellation scheme while performing a signal detecting operation; and performing the signal detecting operation using the interference cancellation scheme, or performing the signal detecting operation without using the interference cancellation scheme based on determining whether there is the need for using the interference cancellation scheme.

Abstract: A method for detecting soft-decisions in a 2×2 MIMO system includes detecting all candidate symbol vector sets S in which there exist all values of a real part and an imaginary part, and calculating a log-likelihood ratio (LLR) with respect to the candidate symbol vector sets S from LLR ? ( b k i ) = min s ? S ? ? i , k - ? ED ? ( s ) 2 ? ? n 2 - min s ? S ? ? i , k + ? ED ? ( s ) 2 ? ? n 2 .

Abstract: A method of operating a wireless local area network (WLAN) station. The WLAN station receives at least one desired signal and at least one interference signal from an access point (AP) capable of simultaneously transmitting desired signals to multiple WLAN stations. The method includes estimating a channel and generating a channel matrix estimated based on the estimated channel, separating a channel matrix of the desired signal and a channel matrix of the interference signal from the estimated channel matrix, generating the matrix of a virtual channel by combining the separated channel matrixes, and executing a sphere decoding (SD) algorithm using the matrix of the virtual channel. Or, separating a desired signal and an interference signal from the stream signal based on the analysis result, ascertaining a modulation scheme of the interference signal, and setting the ascertained modulation scheme of the interference signal as decreased lattice points.

Abstract: A method of operating a wireless local area network (WLAN) station. The WLAN station receives at least one desired signal and at least one interference signal from an access point (AP) capable of simultaneously transmitting desired signals to multiple WLAN stations. The method includes estimating a channel and generating a channel matrix estimated based on the estimated channel, separating a channel matrix of the desired signal and a channel matrix of the interference signal from the estimated channel matrix, generating the matrix of a virtual channel by combining the separated channel matrixes, and executing a sphere decoding (SD) algorithm using the matrix of the virtual channel. Or, separating a desired signal and an interference signal from the stream signal based on the analysis result, ascertaining a modulation scheme of the interference signal, and setting the ascertained modulation scheme of the interference signal as decreased lattice points.

Abstract: A method of operating a wireless local area network (WLAN) system is provided. The WLAN includes an access point supporting uplink multiple user multiple input multiple output mode. The method of operating the WLAN system includes selecting a first station, receiving channel information from the selected first station by a second station, calculating a SNR reduction value based on the channel information by the second station, and selecting the second station based on the SNR reduction value.

Abstract: A method of demodulating a modified dual carrier modulation (MDCM) signal using hard decision includes generating real symbol vector candidates and imaginary symbol vector candidates which correspond to an MDCM signal pair; calculating a first norm between a real part of the MDCM signal pair and each of the real symbol vector candidates and determining as a real symbol vector a real symbol vector candidate that has the minimum first norm among the real symbol vector candidates; and calculating a second norm between an imaginary part of the MDCM signal pair and each of the imaginary symbol vector candidates and determining as an imaginary symbol vector an imaginary symbol vector candidate that has the minimum second norm among the imaginary symbol vector candidates.

Abstract: A method for detecting soft-decisions in a 2×2 MIMO system includes detecting all candidate symbol vector sets S in which there exist all values of a real part and an imaginary part, and calculating a log-likelihood ratio (LLR) with respect to the candidate symbol vector sets S from LLR ? ( b k i ) = min s ? S ? ? i , k - ? ED ? ( s ) 2 ? ? n 2 - min s ? S ? ? i , k + ? ED ? ( s ) 2 ? ? n 2 .

Abstract: A mobile terminal communicates with a base station to request channel allocation for RFID communication, receives a channel from the base station, and communicates with an RFID tag through the allocated channel.

Abstract: In a method of communicating in a radio frequency identification (RFID) system including a RFID reader and a plurality of RFID tags, a plurality of spread spectrum data are stored in the plurality of RFID tags. The plurality of spread spectrum data are transmitted from the plurality of RFID tags to the RFID reader. A plurality of original data respectively corresponding to the plurality of RFID tags are simultaneously extracted from the plurality of spread spectrum data at the RFID reader.

Abstract: Provided are an RFID reader and a data recovery method which selectively selects only an integrity-checked phase signal, when receiving a backscattered signal of an RFID tag through an I signal path or a Q signal path, and may reduce a shadow area of a read range. The RFID reader includes a signal receiver which receives a plurality of phase signals; a symbol detector which recovers data with respect to each of the received phase signals; and a signal selector which selects a signal that satisfies a predetermined standard, from the data-recovered phase signals.

Abstract: A method of upgrading an operation program in an interrogator of a radio frequency identification (RFID) system including the interrogator and a transponder is provided. The method includes transmitting, from the interrogator to the transponder, a first message requesting an operation program upgrade based on information exchanged between the interrogator and the transponder; receiving, at the interrogator from the transponder, a second message that includes a new-version operation program in response to the first message; and installing, at the interrogator, the new-version operation program to upgrade the operation program in the interrogator.

Abstract: A radio frequency identification (RFID) interrogator for determining a bandwidth of a backscattering signal to be backscattered by an RFID tag and a method of operating the same are provided. The RFID interrogator senses a predetermined frequency band to determine whether the predetermined frequency band has been occupied and determines a sensing result. The RFID interrogator further controls the bandwidth of the backscattering signal in response to the sensing result.

Abstract: An anti-collision method is provided for a radio frequency identification (RFID) system including a reader, and two or more tags each having an ID. The anti-collision method includes transmitting an ID request value from the reader to the respective tags, the ID request value containing one or more of the codes forming the ID, receiving the ID from at least one of the tags which contain the ID request value, when a plurality of IDs collide, requesting the tags for a value representing a position of collision, and receiving the value representing the position of collision from the tags and identifying the IDs of the tags. Because collision pattern of the bits of respective IDs is recognized, and a plurality of IDs are recognized, the number of transmissions between the reader and the tags can be reduced.

Abstract: An antenna applied to a slide type mobile communication terminal includes a first board mounted in a first body; a second board mounted in a second body; a radiating element mounted to the second body; and a first contact formed to connect to the second board at one end and contact with the first board at the other end when the first body slides. Accordingly, an antenna with directionality can be realized for applications to short range communication systems.

Abstract: A wireless terminal and a radio frequency identification system for providing additional information and a method of providing additional information using the wireless terminal and the radio frequency identification system. The wireless terminal includes: a tag reader reading tag data from a radio frequency identification tag; a controller generating an additional information request signal with respect to the read tag data; and a communication network interface transmitting the additional information request signal through a communication network and receiving additional information with respect to the additional information request signal. Since the controller of the wireless terminal controls the radio frequency identification reader by optimally setting the information required for determining the time point for the radio frequency identification reader tag to respond, and utilizing the stored address of the additional information providing server, the additional information can be efficiently provided.