8,341 research outputs found
Cross Z-Complementary Pairs for Optimal Training in Spatial Modulation Over Frequency Selective Channels
The contributions of this article are twofold: Firstly, we introduce a novel class of sequence pairs, called “cross Z-complementary pairs (CZCPs),” each displaying zero-correlation zone (ZCZ) properties for both their aperiodic autocorrelation sums and crosscorrelation sums. Systematic constructions of perfect CZCPs based on selected Golay complementary pairs (GCPs) are presented. Secondly, we point out that CZCPs can be utilized as a key component in designing training sequences for broadband spatial modulation (SM) systems. We show that our proposed SM training sequences derived from CZCPs lead to optimal channel estimation performance over frequency-selective channels
Enhanced Cross Z-Complementary Set and Its Application in Generalized Spatial Modulation
Generalized spatial modulation (GSM) is a novel multiple-antenna technique
offering flexibility among spectral efficiency, energy efficiency, and the cost
of RF chains. In this paper, a novel class of sequence sets, called enhanced
cross Zcomplementary set (E-CZCS), is proposed for efficient training sequence
design in broadband GSM systems. Specifically, an E-CZCS consists of multiple
CZCSs possessing front-end and tail-end zero-correlation zones (ZCZs), whereby
any two distinct CZCSs have a tail-end ZCZ when a novel type of cross-channel
aperiodic correlation sums is considered. The theoretical upper bound on the
ZCZ width is first derived, upon which optimal E-CZCSs with flexible parameters
are constructed. For optimal channel estimation over frequency-selective
channels, we introduce and evaluate a novel GSM training framework employing
the proposed E-CZCSs
Spatial encoding in primate hippocampus during free navigation.
The hippocampus comprises two neural signals-place cells and θ oscillations-that contribute to facets of spatial navigation. Although their complementary relationship has been well established in rodents, their respective contributions in the primate brain during free navigation remains unclear. Here, we recorded neural activity in the hippocampus of freely moving marmosets as they naturally explored a spatial environment to more explicitly investigate this issue. We report place cells in marmoset hippocampus during free navigation that exhibit remarkable parallels to analogous neurons in other mammalian species. Although θ oscillations were prevalent in the marmoset hippocampus, the patterns of activity were notably different than in other taxa. This local field potential oscillation occurred in short bouts (approximately .4 s)-rather than continuously-and was neither significantly modulated by locomotion nor consistently coupled to place-cell activity. These findings suggest that the relationship between place-cell activity and θ oscillations in primate hippocampus during free navigation differs substantially from rodents and paint an intriguing comparative picture regarding the neural basis of spatial navigation across mammals
A Direct Construction of Optimal Symmetrical Z-Complementary Code Sets of Prime Power Lengths
This paper presents a direct construction of an optimal symmetrical
Z-complementary code set (SZCCS) of prime power lengths using a multi-variable
function (MVF). SZCCS is a natural extension of the Z-complementary code set
(ZCCS), which has only front-end zero correlation zone (ZCZ) width. SZCCS has
both front-end and tail-end ZCZ width. SZCCSs are used in developing optimal
training sequences for broadband generalized spatial modulation systems over
frequency-selective channels because they have ZCZ width on both the front and
tail ends. The construction of optimal SZCCS with large set sizes and prime
power lengths is presented for the first time in this paper. Furthermore, it is
worth noting that several existing works on ZCCS and SZCCS can be viewed as
special cases of the proposed construction
Root Cross Z-Complementary Pairs with Large ZCZ Width
In this paper, we present a new family of cross -complementary pairs
(CZCPs) based on generalized Boolean functions and two roots of unity. Our key
idea is to consider an arbitrary partition of the set with
two subsets corresponding to two given roots of unity for which two truncated
sequences of new alphabet size determined by the two roots of unity are
obtained. We show that these two truncated sequences form a new -ary CZCP
with flexible sequence length and large zero-correlation zone width.
Furthermore, we derive an enumeration formula by considering the Stirling
number of the second kind for the partitions and show that the number of
constructed CZCPs increases significantly compared to the existing works.Comment: This work has been presented in 2022 IEEE International Symposium on
Information Theory (ISIT), Espoo, Finlan
A New Construction of Enhanced Cross Z-Complementary Sets With Maximum Zero Correlation Zone
Recently, the concept of enhanced cross Zcomplementary sets (E-CZCS) has been proposed for training sequence design in generalized spatial modulation (GSM). Based on generalized Boolean functions, we present a new construction of E-CZCSs having maximum zero correlation zone (ZCZ) width. Based on the proposed E-CZCSs, numerical simulation results indicate that the resultant training sequences lead to superior channel estimation performance in broadband GSM systems
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