Tasks

Diversity vs Multiplexing

Instructions

To understand the diversity-multiplexing tradeoff in MIMO systems, follow these steps:


  1. Begin by observing the default 2×2 MIMO configuration and note the maximum values for diversity gain (reliability) and multiplexing gain (data rate).
  2. Experiment with different numbers of transmit (Tx) and receive (Rx) antennas to see how they affect the maximum achievable diversity and multiplexing gains.
  3. When in "Fixed Multiplexing (R)" mode, adjust the R value to see how prioritizing data rate reduces the available diversity gain.
  4. Switch to "Fixed Diversity (Pe)" mode to see how prioritizing reliability affects the achievable multiplexing gain.
  5. Observe how the operating point (red dot) moves along the tradeoff curve as you adjust parameters.
  6. Note that the maximum multiplexing gain equals min(Nt, Nr) while the maximum diversity gain equals Nt × Nr.
  7. The SNR parameter affects the absolute performance but not the fundamental tradeoff relationship.

This experiment demonstrates the fundamental diversity-multiplexing tradeoff described by Zheng and Tse, showing that increasing one gain necessarily comes at the expense of the other.


System Parameters

Transmitter

Receiver

Explanation:

The diversity-multiplexing tradeoff (DMT) shows the fundamental relationship between reliability (diversity gain) and data rate (multiplexing gain) in MIMO wireless systems. For a 2×2 MIMO system, the maximum diversity gain is 4 and the maximum multiplexing gain is 2.

With fixed multiplexing gain r = 2, the achievable diversity gain is approximately 0.0.

Tradeoff Curve

Key Points:

  • Maximum diversity gain: N/A
  • Maximum multiplexing gain: N/A
  • Operating point: r = ?, d = ?