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Channel Estimation Sequence for TGad

Channel Estimation Sequence for TGad. Authors:. Date: 2010-02-27. Abstract. A channel estimation sequence construction is proposed for TGad. It allows to estimate easily the channel response and the IQ imbalance parameters.

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Channel Estimation Sequence for TGad

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  1. Channel Estimation Sequence for TGad Authors: Date: 2010-02-27 André Bourdoux, IMEC

  2. Abstract A channel estimation sequence construction is proposed for TGad. It allows to estimate easily the channel response and the IQ imbalance parameters. André Bourdoux, IMEC

  3. Channel estimation sequence (CES) constructed from Golay complementary pair Cyclic prefix Cyclic postfix aR a256 =[aLaR] aL bR b256 =[bLbR] bL • a256 and b256 are complementary Golay sequences i.e. a Golay Complementary Pair (GCP) • Main advantage: • sum of auto-correlation sequences is ideal (see next slide) • easy generation and correlation with lattice structure [Budisin – Electronic Letters – January 1991] • NB: - this construction was proposed in an early draft of SC PHY in IEEE802.15.3c • - length 256 is illustrated here as an example André Bourdoux, IMEC

  4. Periodic correlation of “randomly” chosen GCP  |X(a,a*)| Non zero-side lobes |X(b,b*)| Non zero-side lobes |X(a,a*)+X(b,b*)| Zero-side lobes • X(a,a*) is the correlation with a*=conj(a) i.e. the matched filter • X(a,a*) and X(b,b*) are not usable alone because of non-zero sidelobes • Only X(a,a*)+X(b,b*) is exploitable André Bourdoux, IMEC

  5. Basic CES processing X( . ,a*) ca h CES X( . ,b*) cb z-2N ca +cb ca X(a,a*) ▪ ▪ ▪ X(b,a*) cb X(a,b*) ▪ ▪ ▪ X(b,b*) ca + cb` ▪ ▪ ▪ X(a,a*) ▪ ▪ + ▪ ▪ ▪ X(b,b*) ▪ ▪ ▪ André Bourdoux, IMEC

  6. Received ca and cb with “randomly” chosen GCP  ca cb ca + cb AWGN Multipath André Bourdoux, IMEC

  7. First desired cyclic correlation properties of the GCP  |X(a,a*)| |X(b,b*)| |X(a,a*)+X(b,b*)| • X(a,a*) and X(b,b*) are usable alone because of zero-correlation zone of length N/4=64 • X(a,a*)+X(b,b*) is also exploitable André Bourdoux, IMEC

  8. Second desired cyclic correlation properties of the GCP  |X(a,a)| |X(b,b)| |X(a,a)+X(b,b)| • X(a,a) and X(b,b) also have a zero-correlation zone of length N/4=64 André Bourdoux, IMEC

  9. Third desired cyclic correlation properties of the GCP  |X(a,b*)| becausea = -b* |X(b,a*)| |X(a,b*)+X(b,a*)| • X(a,b*) and X(b,a*) also have a zero-correlation zone of length N/4=64 André Bourdoux, IMEC

  10. Response with good GCP  ca cb ca + cb AWGN Multipath André Bourdoux, IMEC

  11. Response with a256 and b256 from the approved SC PHY in IEEE802.15.3c  ca cb ca + cb AWGN Multipath André Bourdoux, IMEC

  12. RX IQ imbalance creates self-interference The desired signal is corrupted by its complex conjugate André Bourdoux, IMEC

  13. Response with IQ imbalance, good GCP  Nh Nh Nh* ca Nh Nh* Nh cb ca + cb Without IQ imbalance With IQ imbalance The ratio /* can easily be estimated André Bourdoux, IMEC

  14. IQ compensation Received signal: For the compensation of the received signal, we just need /*: This small amplitude coefficient will be compensated for by the equalizer André Bourdoux, IMEC

  15. Summary • A Golay complementary pair (GCP) is a good candidate for the channel estimation sequence • The GCP can be chosen to ease the estimation of the IQ imbalance parameters: in particular, GCP with maximal length (N/4) zero-correlation zones are ideal • Easy estimation of channel response and IQ imbalance possible if: • GCP have properties in slide 7,8 and 9 (zero correlation zones) • Preamble is built as in slide 3 (pre- and post-fix) André Bourdoux, IMEC

  16. Staw Poll Questions • Do you support inclusion of the technique, • Golay complementary pair with maximum length zero-correlation zone for the estimation of the channel response and IQ imbalance • as described in 10/0264r3 in the TGad draft amendment? André Bourdoux, IMEC

  17. References • 11-09-0296-16-00ad-evaluation-methodology.doc • 11-09-0228-05-00ad-functional-requirements.doc • IEEE Std 802.15.3c™-2009 • IEEE P802.15.3c/DF3 André Bourdoux, IMEC

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