Transmission of Information by Orthogonal Functions

Harmuth, Henning F.

doi:10.1007/978-3-642-61974-8

Cited by 212 publications

(36 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…2(b), training symbols are transmitted simultaneously in both MC and SCs. From the point of view of the MC, the MBS transmits to the MUEs a unit norm Walsh-Hadamard (W-H) sequence [16] x m of length τ 2 at each subcarrier. Note that, τ 2 size depends on the number of both subcarriers and performed channel estimations.…”

Section: B DL Channel Estimation (τ 2 )mentioning

confidence: 99%

Channel estimation impact for LTE small cells based on MU-VFDM

Maso

Cardoso

Debbah

et al. 2012

2012 IEEE Wireless Communications and Networking Conference (WCNC)

View full text Add to dashboard Cite

In a previous work, we introduced a spectrum sharing technique called Multi-User Vandermonde-subspace Frequency Division Multiplexing (MU-VFDM). This overlay technique allows the coexistence of a downlink Orthogonal Frequency Division Multiple Access (OFDMA) macro-cell and a cognitive multi-user small-cell system in time division duplex mode. In that work, MU-VFDM was shown to be able to completely cancel the interference towards a macro-cell system at the price of perfect channel state information (CSI) at the opportunistic small-cells. In this work we relax the perfect CSI constraint by introducing a channel estimation protocol that does not require cooperation between the two systems, but still provides harmless coexistence between them. The impact of this protocol is evaluated in terms of interference at the legacy and sum-rates at the opportunistic system. Simulation results show that, even with imperfect CSI estimation, MU-VFDM is able to achieve promising rates for the small-cells while incurring a small rate loss at the macro-cell due to interference

show abstract

Section: B DL Channel Estimation (τ 2 )mentioning

confidence: 99%

Channel estimation impact for LTE small cells based on MU-VFDM

Maso

Cardoso

Debbah

et al. 2012

2012 IEEE Wireless Communications and Networking Conference (WCNC)

View full text Add to dashboard Cite

show abstract

“…The volume and of the resulting region can be computed for as (37) and (38) Substituting these expressions into (30) yields the shaping gain for these peak-constrained regions. Note also that peak optical power in the case of these regions is and gives a PAR of PAR which is independent of the symbol interval.…”

Section: K Shaping Gain: Peak-symmetric Schemesmentioning

confidence: 99%

“…Adaptively biased QAM (AB-QAM) [11], [37] is a 3-D modulation scheme which is defined using the basis functions More generally, these functions are Walsh functions. This characterization is especially useful in light of the signal space definition in Section III-A, since the basis functions of AB-QAM are scaled and shifted versions of the first three Walsh functions [38].…”

Section: A Definition Of Example Schemesmentioning

confidence: 99%

Optical intensity-modulated direct detection channels: signal space and lattice codes

Hranilovic

Kschischang

2003

IEEE Trans. Inform. Theory

101

View full text Add to dashboard Cite

Traditional approaches to constructing constellations for electrical channels cannot be applied directly to the optical intensity channel. This work presents a structured signal space model for optical intensity channels where the nonnegativity and average amplitude constraints are represented geometrically. Lattice codes satisfying channel constraints are defined and coding and shaping gain relative to a baseline are computed. An effective signal space dimension is defined to represent the precise impact of coding and shaping on bandwidth. Average optical power minimizing shaping regions are derived in some special cases. Example lattice codes are constructed and their performance on an idealized point-to-point wireless optical link is computed. Bandwidth-efficient schemes are shown to have promise for high data-rate applications, but require greater average optical power.Index Terms-Free-space optical communications, lattice codes, optical intensity modulation, signal space, wireless infrared channel.

show abstract

“…Unfortunately, up to now, thxe is still no unified proof of the invariance for all of the o r lerings. The only proof available is of show-by-example t l ,e illustration [l], [2], [4], [5] which, though demonstrates tb ; invariant property, does not provide a rigorous treatment of the dyadic shift invariance. As an example, let { T } be an 12'-periodic sequence and { T , } be the sequence subjects to a J \ adic shift of size k , and { X } be the WHT of {x} and { X , } bc.…”

Section: Introductionmentioning

confidence: 99%

“…Classical control methods are well known; however, they are inadequate in the presence of strong nonlinearities. On the other hand, nonlinear controllers [ 11- [4] produce better results but the nonlinear analysis and design is not as systematic and clear as the linear case. Some work has been done on relating linear methods to manipulator dynamics [5]-[ 141.…”

Section: Introductionmentioning

confidence: 99%