Questions tagged [mimo]
The mimo tag has no summary.
85 questions
0 votes
1 answer
62 views
MIMO LMMSE detector
I did the derivation for the LMMSE detector in MIMO long time ago. However, I am confused by some matrix manipulation now. If we have MIMO channel $(Nt\times Nr)$ output $Y = HX + N$, the LMMSE ...
- 55
3 votes
1 answer
243 views
Making the MIMO virtual array size appear in the FFT and Capon angle resolution
Trying to clarify MIMO angle resolution with equations and getting a bit confused. Using this paper's notations ($M$: number of RX, $N$: number of TX, $L$: number of snapshots), the RX signal matrix ...
- 222
0 votes
1 answer
74 views
Which precoder is better in this scenario?
I was asked this question on an interview. I think I have provided a good answer, but I think I am missing something. Appreciate any comments. Problem: In a 2x2 wireless channel, the channel matrix is ...
- 121
1 vote
0 answers
32 views
ML bound for Massive MIMO
How can one estimate the ML bound for Massive Mimo detection with 128 transmitting antenna and 128 receiving antennas using 4 QAM modulation? I have seen for a 8 by 8 system it is possible to use K-...
- 154
1 vote
1 answer
77 views
A question of channel capacity in precoding case
I’ve a general question about precoding. The channel capacity after precoding is $\log_2(\det(I+F’H’HF))$ where $\det$ is the determinant, $I$ the identity matrix, $F$ the precoding matrix, $H$ the ...
- 49
0 votes
1 answer
111 views
SIMO systems diversity and matched filter response
Let's assume we have a SIMO system with multiple transmitter antennas (e.g. qty 4), and a single receiver or 4x1. Let's suppose we're talking about the SSR steady-state response, Gaussian noise, and ...
1 vote
0 answers
244 views
Eigen Beamforming: Explanation [closed]
It's been a few days that I have been searching the term eigen beamforming, but still haven't get any satisfactory literature reference. It would be great if you could give any details or point to any ...
- 145
0 votes
1 answer
164 views
MMSE is approximately zero-forcing at high SNR
In https://stanford.edu/~dntse/Chapters_PDF/Fundamentals_Wireless_Communication_chapter8.pdf page 360, it is stated that for a flat fading MIMO channel with receiver CSI only: at high SNR, the $\...
- 1
1 vote
1 answer
224 views
MIMO reading clarification
On page 301 of https://stanford.edu/~dntse/Chapters_PDF/Fundamentals_Wireless_Communication_chapter7.pdf, equation (7.33) says that the magnitude of the dot product of two unit complex vectors is ...
- 125
4 votes
1 answer
523 views
What wavelength do we use when calculating the array manifold vector when transmitting LFM waveforms?
We know that the array manifold vector, also called the steering vector, for an M element array is given by: $$ \mathbf{a}(\theta, \phi) = [e^{-j \omega \tau_{1}(\theta, \phi)}, e^{-j \omega \tau_{2}(\...
- 652
1 vote
1 answer
354 views
Calculation of the LMMSE Channel Estimator
Consider a MIMO system equipped with $N_t$ transmit antennas and $N_r$ receive antennas. The received signal over $L$ snapshots are given by $$Y = H X + Z,$$ where $X$ is the $N_t \times L$ transmited ...
- 11
1 vote
0 answers
275 views
How to implement maximum likelihood (ML) detector in MATLAB?
Consider the MIMO system which has $N_t$ antennas at transmitter and $N_r$ antennas at receiver and uses Generalized space shift keying (GSSK) modulation. The received signal is given by: $$Y = H X + ...
- 73
0 votes
0 answers
75 views
How to do MIMO precoding for OFDM?
I studied OFDM, MIMO, and MU-MIMO, but I'm not sure how it works when MIMO and OFDM are combined. I can't find good literature that talks about MIMO-OFDM. I want to understand how to use eigenmode ...
- 61
0 votes
0 answers
43 views
How to express random signal in MATLAB which is transmitted from transmitter to receiver
I am trying to model a random transmitted signal between transmitter (source) to receiver. Specifically, the transmitter has $N_s = 1$ antenna and receiver has $N_r = 2$ antennas. My query is that I ...
- 73
1 vote
2 answers
174 views
Can the number of subcarriers/user be greater than 12 in 5G?
In 5G, I think 1 resource block (RB) carrier is 12 subcarriers. So one user uses 12 subcarriers. But in some research, 612 subcarriers are used for channel estimation research. Is it okay to use more ...
- 61