Other

Saankhya Labs Pvt. Ltd.

Shrinivas Subramania Bhat

Anindya Saha

Sudeep Mirpadi Anand

Parag Naik

Vishwakumara Kayargadde

Niranjan Mylarappa Gowda

S Harish Krishnan

Srinidhi Nagaraja

Disclosed is a system for mitigating co-channel interference (CCI) caused due to narrow multiband signal in white space (WS) modems. The system includes a base-station that includes a base-station transmitter and a base-station receiver. The base-station receiver receives an orthogonal frequency division multiplexing signal (OFDM) from one or more customer premises equipment (CPE) transmitters. An interference detection module detects a presence of co-channel interference in carriers of the OFDM signal and determines co-channel interference affected carriers. A dynamic notch filter module receives the central interference carriers from interference detection module and mitigates the co-channel interference of co-channel interference affected carriers without affecting frame detection capability of the system. The base-station transmitter includes an interference aware frequency interleaver that spreads co-channel interference affected carriers based on interference specific interleaving parameters and frequency de-interleaving is performed corresponding to frequency interleaving in the base-station receiver.

System and method for mitigating co-channel interference in white space modems

Disclosed is a system for mitigating co-channel interference (CCI) in white space (WS) modems. The system includes a base-station that includes a base-station transmitter and a base-station receiver. The base-station receiver receives an OFDM signal from one or more CPE transmitters. An interference detection module detects presence of co-channel interference in carriers of the OFDM signal and determines co-channel interference affected carriers. A dynamic notch filter module (i) receives central interference carriers from interference detection module and (ii) mitigates the co-channel interference of co-channel interference affected carriers without affecting frame detection capability of the system. An interference aware signal to noise ratio (SNR) estimation module determines an average signal to noise ratio (SNR) of (i) interference unaffected carriers and (ii) co-channel interference affected carriers. An interference aware de-mapper module processes average signal to noise ratio of (i) interference unaffected carriers and (ii) co-channel interference affected carriers.

System and method for mitigating co-channel interference in white space modems using interference aware techniques

A method of ranging and sub-carrier selection in an orthogonal frequency division multiple access (OFDMA) system and the OFDMA system is disclosed. An OFDM symbol is received from a customer premises equipment (CPE) at a base station. The OFDM symbol is demodulated for obtaining a plurality of subcarriers. A plurality of data subcarriers are multiplied by zeros and stored. A plurality of uniformly spaced subcarriers is extracted from the stored subcarriers. A ranging CPE is detected in uniformly spaced subcarriers. Delay estimation is performed using the stored plurality of subcarriers upon detecting presence of ranging CPE. A method of subcarrier allocation at a ranging CPE transmitter based on total number of subcarriers, subcarriers in used band, a delay spread to be supported in terms of number of samples, a required ratio of highest amplitude to second highest amplitude of the ranging signal is disclosed.

Method and system of ranging and subcarrier allocation in orthogonal frequency division multiple access system

A method of generating a hypothesis and estimating a CFO includes receiving a signal including a set of radio frames, dividing each received radio frame of the set into a set of received sub-sequences, dividing, each of reference radio frames from a reference signal stored in the receiver into a set of reference sub-sequences, correlating the set of received sub-sequences with the set of reference sub-sequences to obtain a set of correlation values, generating, a first value set and a second value set of hypothesis based on the correlation values, generating a first and a second hypothesis based on the first value and the second value set, and averaging the first and the second hypothesis to obtain an averaged hypothesis, performing a DFT on the averaged hypothesis to obtain a DFT sequence, determining a peak position of the DFT sequence, and estimating the CFO based on the peak position.

Scheme for generating hypothesis and estimating a carrier frequency offset in a receiver

An Orthogonal Frequency Division Multiplexing (OFDM) receiver system for improved pilotless detection of symbol boundary of a received OFDM symbols using M-ary Phase Shift Keying (M-PSK) modulated carriers as a cost function. The OFDM receiver includes a symbol boundary detection block that detects a symbol boundary of the received OFDM symbols. The symbol boundary detection block detects the symbol boundary by computing a cost function of a second order moment of the M-PSK modulated carriers. The receiver system detects the symbol boundary for unknown information on the received OFDM symbols.

Blind symbol synchronization scheme for OFDM system

A receiver and method of detecting a guard interval estimate accurately by performing an Nth order polynomial based non-linear quantization on a pre-estimated guard interval in a received Orthogonal Frequency Division Multiplexing (OFDM) signal in a receiver is provided. The pre-estimated guard interval is obtained by performing normalized auto-correlation on the received OFDM signal. The method includes (i) performing a rounding operation on (a) one or more mcoefficient of the polynomial and (b) the pre-estimated guard interval to obtain an indexing parameter 'k', and detecting the guard interval estimate based on (i) a value of k, and (ii) a guard interval from one or more guard intervals that are stored in a look up table. The guard interval estimate is detected in accordance with an equation: {tilde over (L)}=L[k&#x2212;4], where 'L' is the guard interval stored in the look up table that corresponds to the value of k.

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Bengaluru, India

Shrinivas Subramania Bhat