• Six equalizers for V-BLAST

    Apr 21st, 200967 Comments

    In the past, we had discussed several posts on two transmit two receive MIMO communication, where the transmission was based on V-BLAST. The details about V-BLAST can be read from the landmark paper V-BLAST: An [...]

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    ber_plot_2transmit_2receive_mimo_with_bpsk_in_rayleigh_channel

  • Transmit beamforming

    Apr 13th, 200963 Comments

    In this post lets discuss a closed-loop transmit diversity scheme, where the transmitter has the knowledge of the channel. As there is a feedback path required from the receiver, to communicate the channel seen by [...]

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    ber_plot_2transmit_1receive_transmit_beamforming_with_bpsk_in_rayleigh_channel

  • Alamouti STBC with 2 receive antenna

    Mar 15th, 2009147 Comments

    In the past, we had discussed two transmit, one receive antenna Alamouti Space Time Block Coding (STBC) scheme. In this post, lets us discuss the impact of having two antennas at the receiver. For the [...]

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    2transmit_2receive_alamouti_stbc

  • MIMO with ML equalization

    Dec 14th, 200897 Comments

    We have discussed quite a few receiver structures for a 2×2 MIMO channel namely, (a) Zero Forcing (ZF) equalization (b) Minimum Mean Square Error (MMSE) equalization (c) Zero Forcing equalization with Successive Interference Cancellation (ZF-SIC) [...]

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    BER plot 2x2 MIMO Rayleigh channel with Maximum Likelihood equalisation

  • MIMO with MMSE SIC and optimal ordering

    Dec 6th, 200826 Comments

    This post attempts to build further on the MIMO equalization schemes which we have discussed – (a) Minimum Mean Square Error (MMSE) equalization, (b) Zero Forcing equalization with Successive Interference Cancellation (ZF-SIC) and (c) ZF-SIC [...]

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    2x2 MIMO MMSE-SIC equalization

  • MIMO with ZF SIC and optimal ordering

    Nov 29th, 200827 Comments

    In previous posts, we had discussed equalization of a 2×2 MIMO channel with Zero Forcing (ZF) equalization and later, Zero Forcing equalization with successive interference cancellation (ZF-SIC). In this post, we will explore a variant [...]

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    2x2 MIMO equalized by ZF-SIC with optimal ordering

  • MIMO with Zero Forcing Successive Interference Cancellation equalizer

    Nov 9th, 200864 Comments

    The post on MIMO with Zero Forcing equalizer discussed a probable way of equalizing a 2×2 MIMO channel. The simulated results with the 2×2 MIMO system with zero forcing equalizer showed matching results as obtained [...]

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    BER plot for BPSK in 2x2 MIMO channel with Zero Forcing Successive Interference Cancellation equalization

  • MIMO with MMSE equalizer

    Nov 2nd, 2008245 Comments

    In a previous post, we had discussed a 2×2 MIMO transmission using BPSK modulation in Rayleigh channel with a Zero Forcing equalizer. The simulated results with the 2×2 MIMO system  with zero forcing equalizer showed [...]

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    BER plot for 2x2 MIMO with MMSE equalization for BPSK in Rayleigh channel

  • MIMO with Zero Forcing equalizer

    Oct 24th, 2008154 Comments

    We had discussed three Single Input Multiple Output (SIMO also known as receive diversity) schemes – Selection combining, Equal Gain Combining, Maximal Ratio Combining and a Multiple Input Single Output (MISO, also known as transmit [...]

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    BER plot for 2x2 MIMO channel with ZF receiver (BPSK modulation in Rayleigh channel)

  • Alamouti STBC

    Oct 16th, 2008273 Comments

    In the recent past, we have discussed three receive diversity schemes – Selection combining, Equal Gain Combining and Maximal Ratio Combining. All the three approaches used the antenna array at the receiver to improve the [...]

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    2Transmit, 1Receive Alamouti STBC coding

Filter

Frequency response Zero Forcing equalizer
BER for BPSK in ISI channel with Zero Forcing equalization

Nov 29th, 200957 Comments

Eye diagram following raised cosine filtering with alpha=0.5
Eye diagram with raised cosine filtering

May 1st, 200820 Comments

Time domain response of raised cosine filter
Raised cosine filter for transmit pulse shaping

Apr 22nd, 200844 Comments

OFDM

IEEE 802.11ac – Very High Throughput for lower 6GHz band

Apr 26th, 20109 Comments

Quiz on IEEE 802.11a specifications

Oct 7th, 200910 Comments

Plot of the magnitude of error vs frequency offset in OFDM Inter Carrier Interference (ICI) in OFDM due to frequency offset

Aug 8th, 200965 Comments

BER plot for BPSK with OFDM modulation in a 10-tap Rayleigh fading channel BER for BPSK in OFDM with Rayleigh multipath channel

Aug 26th, 2008319 Comments

OFDM PAPR for BPSK/QPSK with j rotation Trying out PAPR reduction for OFDM by multiplication with j

Jul 2nd, 200847 Comments

MIMO

ber_plot_2transmit_2receive_mimo_with_bpsk_in_rayleigh_channel Six equalizers for V-BLAST

Apr 21st, 200967 Comments

ber_plot_2transmit_1receive_transmit_beamforming_with_bpsk_in_rayleigh_channel Transmit beamforming

Apr 13th, 200963 Comments

2transmit_2receive_alamouti_stbc Alamouti STBC with 2 receive antenna

Mar 15th, 2009147 Comments

BER plot 2x2 MIMO Rayleigh channel with Maximum Likelihood equalisation MIMO with ML equalization

Dec 14th, 200897 Comments

2x2 MIMO MMSE-SIC equalization MIMO with MMSE SIC and optimal ordering

Dec 6th, 200826 Comments

Analog

iq_modulator_with_gain_phase_imbalance
Image Rejection Ratio (IMRR) with transmit IQ gain/phase imbalance

The post on IQ imbalance in transmitter, briefly discussed the effect of amplitude and phase imbalance and also showed that IQ imbalance results in spectrum at the image frequency. In this article, we will quantify [...]

Modulation

plot_symbol_error_rate_16qam_64qam_256qam_ofdm_awgn
Symbol Error rate for QAM (16, 64, 256,.., M-QAM)

In May 2008, we derived the theoretical symbol error rate for a general M-QAM modulation (in  Embedded.com, DSPDesignLine.com and dsplog.com) under Additive White Gaussian Noise. While re-reading that post, felt that the article is nice and warrants a [...]

Channel

BER plot for BPSK in a 3 tap ISI channel with MMSE equalizer
BER for BPSK in ISI channel with MMSE equalization

In the past, we had discussed BER for BPSK in flat fading Rayleigh channel and BER for BPSK in a frequency selective channel using Zero Forcing Equalization. In this post, lets discuss a frequency selective [...]

News

Migrated to Amazon EC2 instance (from shared hosting)

Mar 11th, 2013No Comments

Update : Correction to solution of GATE-2012 ECE Q38

Nov 9th, 20122 Comments

Migration to new template (skin)

Sep 11th, 2012No Comments

Solved!

Apr 4th, 20122 Comments

Back!

Oct 22nd, 20119 Comments

DSP

Modeling phase noise (frequency domain approach)

Sep 30th, 20121 Comment

Weighted Least Squares and locally weighted linear regression

Feb 5th, 2012No Comments

Least Squares in Gaussian Noise – Maximum Likelihood

Jan 15th, 2012No Comments

Newton’s method to find square root, inverse

Dec 25th, 20111 Comment

Closed form solution for linear regression

Dec 4th, 201110 Comments

Coding

ber_plot_hamming_7_4_code_soft_and_hard_decode_in_awgn
Hamming (7,4) code with soft and hard decoding

An earlier post we discussed hard decision decoding for a Hamming (7,4) code and simulated the the bit error rate. In this post, let us focus on the soft decision decoding for the Hamming (7,4) [...]

GATE

quarter_wave_matching_transformer
GATE-2012 ECE Q28 (electromagnetics)

Question 28 on electromagnetics from GATE (Graduate Aptitude Test in Engineering) 2012 Electronics and Communication Engineering paper. Q28. A transmission line with a characteristic impedance of 100 is used to match a 50 section to a 200 section. If the matching [...]

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