ECE 5325 Wireless Communications
MIMO and LTE
Given that M x M MIMO achieves a capacity of C/B = E { log2 | I + Eb/No * 1/M * HHH
* Rb/B | }, where E { | Hij | } = 1, compute and plot the following curves. Use Rb/B = 1/
BT = 1/0.5 = 2 for GMSK with BT = 0.5. Simulate H as H = ( randn(M,M) + j *
randn(M,M) ) / sqrt(2). To avoid issues with complex number handling in matlab,
compute |x| as det(abs(x)).
Q1: Simulate capacities for various numbers of antennas by averaging the capacity
computed for a thousand random H-matrices. Plot these capacities as a function of
Eb/No for 6 < Eb/No < 30 dB.
(a) SISO: 1 x 1 (Rx, Tx)
(b) MIMO: 2 x 2 (Rx, Tx)
(c) MIMO: 4 x 4 (Rx, Tx)
(d) MIMO: 10 x 10 (Rx, Tx)
Q2: What is the peak download rate in 3GPP-LTE? (See
http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution.) How many MIMO does that
require at the receiver and at the transmitter?
Q3: Assuming 20 MHz of spectrum, find where this throughput falls on your curves from
Q1. Based on your curve in Q1, what Eb/No must 3GPP-LTE have to achieve this peak
rate (assume 10 dB fading margin and distance of the codec from the Shannon bound)?
Q4: Can you infer from Q1 how much more power (Eb/No) a SISO link would require to
achieve this same throughput (Rb or C)? Explain.
Q5: What peak download rate has been released in LTE Advanced (3GPP Release 10)?
Q6: How do LTE users share spectrum, i.e. what method of multiple access is employed
(E-UTRA Air interface)?
Q7: How does LTE (4G cellular) link spectral efficiency compare with GSM+EDGE?
How does it compare to CMDA2000 1xEV-DO? How does it compare with digital cable
TV via fiber optics and 256-QAM – both in bandwidth and efficiency?
Q8: How does LTE (4G cellular) system spectral efficiency compare with GSM+EDGE?
How does it compare to CMDA2000 1xEV-DO?
Q9: List three reasons why a typical user would not see this level of benefit over other
communications standards any time soon.
Q10: What is CDMA2000 EV-DO? (Check the links on the right-hand side bar on the
3GPP LTE Wikipedia page.)
UNIVERSITY OF UTAH DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
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