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Optimal Pilot Design for OTFS in Linear Time-Varying Channels

Ids van der Werf, Richard Heusdens, Richard C. Hendriks, Geert Leus

TL;DR

The positioning of the pilot symbols, as well as the power distribution between the pilot and the communication symbols in the orthogonal time frequency space (OTFS) modulation scheme, are investigated to provide valuable guidance for designing the OTFS parameters to achieve maximum capacity.

Abstract

This paper investigates the positioning of the pilot symbols, as well as the power distribution between the pilot and the communication symbols in the orthogonal time frequency space (OTFS) modulation scheme. We analyze the pilot placements that minimize the mean squared error (MSE) in estimating the channel taps. This allows us to identify two new pilot allocations for OTFS. In addition, we optimize the average channel capacity by adjusting the power balance. We show that this leads to a significant increase in average capacity. The results provide valuable guidance for designing the OTFS parameters to achieve maximum capacity. Numerical simulations are performed to validate the findings.

Optimal Pilot Design for OTFS in Linear Time-Varying Channels

TL;DR

The positioning of the pilot symbols, as well as the power distribution between the pilot and the communication symbols in the orthogonal time frequency space (OTFS) modulation scheme, are investigated to provide valuable guidance for designing the OTFS parameters to achieve maximum capacity.

Abstract

This paper investigates the positioning of the pilot symbols, as well as the power distribution between the pilot and the communication symbols in the orthogonal time frequency space (OTFS) modulation scheme. We analyze the pilot placements that minimize the mean squared error (MSE) in estimating the channel taps. This allows us to identify two new pilot allocations for OTFS. In addition, we optimize the average channel capacity by adjusting the power balance. We show that this leads to a significant increase in average capacity. The results provide valuable guidance for designing the OTFS parameters to achieve maximum capacity. Numerical simulations are performed to validate the findings.
Paper Structure (24 sections, 50 equations, 8 figures, 2 tables)

This paper contains 24 sections, 50 equations, 8 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Signal model
  3. OTFS transmitter
  4. Channel Model
  5. OTFS receiver
  6. Related work on pilot design
  7. Optimal pilot design in an LTI channel
  8. Optimal pilot design in an LTV channel
  9. Pilot allocation for OTFS
  10. Pilot allocation for OSDM
  11. OTFS/OSDM modulation through the LTV channel
  12. Pilot distribution for OTFS
  13. Step 1) Analyzing possible pilot allocations
  14. Step 2) Determining the pilot allocations with the lowest overhead
  15. Step 3) Showing MMSE optimality
  16. ...and 9 more sections

Figures (8)

  • Figure 1: Visualization of the OTFS transmitter, $\{K,N,M\} = \{18,3,6\}$.
  • Figure 2: Two methods, as proposed by (a)ma2003optimalkannu2005mseoptimalkannu2008design and (b)kannu2005mseoptimalkannu2008design.
  • Figure 3: Pilot allocations in the delay-Doppler and time-frequency domain.
  • Figure 4: Pilot allocation as proposed by sanoopkumar2023apractical.
  • Figure 5: Time-frequency plot for D-OSDM ebihara2016dopplerresilient.
  • ...and 3 more figures

Theorems & Definitions (2)

  • Remark 1
  • Remark 2