Abstract: There is provided a jitter measuring apparatus for measuring jitter in a signal-under-measurement having a first pulse generator for detecting edges of the data-signal-under-measurement to output a first pulse signal having a pulse width set in advance corresponding to the edge, a second pulse generator for detecting boundaries of data sections where data values do not change in the data-signal-under-measurement to output a second pulse signal having a pulse width set in advance corresponding to timing of the detected boundaries of the data sections, a filter for removing carrier frequency components of said data-signal-under-measurement from first and second pulse signals and a jitter calculating section for calculating timing jitter in the data-signal-under-measurement based on the first and second pulse signals.

Abstract: A quadrature-multiplexed continuous phase modulation (QM-CPM) signal is made up of the real parts of two underlying CPM signals whose information content can be recovered from just their real parts. The real parts of two such signals are I/Q multiplexed and transmitted onto a single channel to approximately double the bits/Hz of the underlying CPM signals, while maintaining the same or similar minimum distance. A class of QM-CPFSK (QM-continuous phase frequency shift keyed) signals are presented that use binary signaling but more phase states, and M2-ary QM-CPFSK signals are derived from constant envelope M-ary CPFSK signals. M2-ary multi-amplitude CPFSK signaling schemes are constructed that maintain the same distance as known multi-amplitude CPFSK schemes, but more than double the bandwidth efficiency in bits/Hz. In addition to these CPFSK based embodiments, embodiments are provided that more generally use CPM, non-continuous phase modulated signals, and even trellis-based PAM based signals.

Abstract: An apparatus and method for simultaneously providing service to users each having a different number of antennas in a multiple-antenna wireless communication system are provided. The communication method discloses a BS in a wireless communication system that services a first multiple antenna mode using X transmit antennas and a second multiple antenna mode using Y transmit antennas such that (Y>X), the BS determines an MS to be serviced in the second multiple antenna mode and receives a sounding signal from the MS. The BS estimates an uplink channel using the received sounding signal and acquires downlink channel values using estimated uplink channel values. Then the BS services the MS in the second multiple antenna mode using the downlink channel values.

Abstract: The present invention provides a method, receiver and transmitter for use in a SDAR system. The method involves generating a first modulated signal based on first input data. Additional modulation is superimposed on the first modulated signal based on additional input data, being spread across a plurality of symbols in the first modulated signal in a predetermined pattern to generate a modified signal which is then transmitted. The modified signal is decoded by performing a first demodulation of the first modulated signal then additional demodulation is performed to obtain additional input data. The superimposing step uses a plurality of offset sequence values to add the additional modulation to the first modulated signal. The offset sequence may appear as a pseudo-random distribution of offset sequence values, and may include at least one zero offset value.

Abstract: A technique for a reconditioning equalizer filter using convolution is described. The input to a transmitter chain is modified by a reconditioning equalizer filter using convolution prior to being applied to the transmitter. The reconditioning equalizer filter modifies and smoothen the amplitude of the main baseband signal. The modified and smoothen main baseband signal has its peaks reduced which results to lower Crest Factor. The input to the reconditioning equalizer filter using convolution could be a baseband, an intermediate frequency (IF) or radio frequency (RF) signal. When the signal is an IF or RF signal it needs to be down converted to baseband before applied to reconditioning equalizer filter using convolution.

Abstract: A technique for a reconditioning equalizer filter for OFDM and non-OFDM signals is described. The input to a transmitter chain is modified by a reconditioning equalizer filter, prior to being applied to the transmitter. The reconditioning equalizer filter modifies and smoothen the amplitude of the signal. The modified and smoothen signal has its peaks reduced which results to lower Crest Factor. The input to the reconditioning equalizer filter could be a baseband, an intermediate frequency (IF) or radio frequency (RF) signal. When the signal is an IF or RF signal it needs to be down converted to baseband before applied to reconditioning equalizer filter.

Abstract: An improved method and apparatus for transmitting digital signals in a communications channel by compensating for distortions due to attenuation of high frequency components suffered by the digital signals. In a preferred embodiment, the digital signals are pulses and the compensation is performed at the transmitter without the need for an emphasis driver, by widening the pulses to compensate for the distortion in the channel that results in narrowing of the pulses incurred in the channel. The resulting pulse train is pre-compensated for the distortions caused by the communications channel. The amount of pre-compensation can be determined statically or dynamically.

Abstract: A training sequence is created for space-time diversity arrangement, having any training sequence length, while limiting the training sequence to a standard constellation. Given a number of channel unknowns that need to be estimated, L, a training sequence can be creates that yields minimum means squared estimation error for lengths Nt=kNPRUS+L?1, for any positive integer k?1, where NPRUS a selected perfect roots-of-unity sequence (PRUS) of length N. The training sequence is created by concatenating k of the length N perfect roots-of-unity sequences, followed by L?1 initial symbols of that same PRUS. Good training sequences can be created for lengths Nt that cannot be obtained through the above method by concatenating a requisite number of symbols found through an exhaustive search.

Abstract: The invention relates to a method of estimating a noise and interference covariance matrix and to a receiver. The method comprises: estimating an initial noise and interference covariance matrix on the basis of a received signal; reducing the impact of the background noise of the receiver from the initial noise and interference covariance matrix for obtaining a residual matrix; accepting the obtained residual matrix when the residual matrix is at least approximately positive semidefinite; modifying the obtained residual matrix such that the positive semidefinity of the residual matrix is achieved when the residual matrix is not at least approximately positive semidefinite; and adding the impact of background noise back to the residual matrix for estimating a final noise and interference covariance matrix.

Abstract: A receiving apparatus receives data sequences, each of which includes plural data blocks, from plural transmission lines, respectively. The apparatus includes plural elastic buffers and a deskew circuit. The corresponding data sequence is written into each elastic buffer. A predetermined number of consecutive timing control symbols are inserted into the data sequences as markers for data blocks to be read from the data sequences at the same cycle. The elastic buffers adjust numbers of the timing control symbols included in the written data sequences, respectively. The data sequences, in each of which the number of the timing control symbols has been adjusted, are read from the elastic buffers in synchronization with a reading clock. The data sequences are written into the deskew circuit. The deskew circuit adjusts the number of the timing control symbols included in each data sequence so as to be equal to the predetermined number.