The geometry of a point cloud is commonly represented by an octree recursively decomposing a 3D volume into eight child sub-volumes. Said volumes and sub-volumes are associated with nodes and child-nodes of the octree. The geometry is defined by the occupancy information indicating the presence or not of a point in each of the sub-volumes. This naturally leads to an eight-bit occupancy information to be coded for each internal node of the tree.

The performance of a two-hop amplify-and-forward relay link in flat Rayleigh fading channels is analyzed. Closed-form expressions are obtained for the distribution of the instantaneous signal-to-noise ratio (SNR). An expression for the error probability is presented in general, and the bit-error rate (BER) associated with binary differential PSK (BDPSK) and the symbol-error rate (SER) associated with M-ary amplitude-shift keying (ASK) modulation schemes are derived in particular. These theoretical results are well supported by simulation results. In principle, the analysis approach, which is different from and much simpler than that reported in [9], can be generalized and applied to relay systems that include more hops.

This paper analyzes the Doppler shift (DS) distribution of the signal received by a mobile station in three-dimensional mobile radio environments. First, from the relationship of the DS and the signal's arriving angles, two equations are derived, bridging the probability density function (pdf) of the elevation angle and the pdf of the DS, as well as the variance of the DS. Then, these equations are applied to the semi- spheroid propagation model recently proposed by Janaswamy. The derived pdf of the DS is equivalent to the signal power-spectral density (PSD) when the average strengths of the waves distributed on different equal-Doppler-shift surfaces (EDSS) are assumed to be equal.

A method to implement OFDM using amplitude shift keying (ASK) for subcarrier modulation is presented in this paper. Because ASK is used, the signal of each symbol in the time domain is conjugate-symmetric. This property is exploited such that only half of the numbers of each symbol sequence are transmitted. The generated baseband signal can be a complex or a real signal. ASK-OFDM has similar bandwidth efficiency and the same error rate performance in an AWGN channel as in a QAM-OFDM. Compared with QAM-OFDM, ASK-OFDM provides a method of distributing signal energy more evenly in the frequency band. In other words, ASK-OFDM signal possesses better frequency diversity than QAM-OFDM signal.

A digital modulation method based on quadrature-carrier multiplexing of two N-dimensional biorthogonal signal sets is proposed. An embodiment of the proposed method referred to as quadrature frequency/phase modulation (QFPM), and its continuous phase modification CP QFPM, are described. QFPM results when two NFSK/2PSK (combined frequency and phase shift keying) signals are quadrature-carrier multiplexed. The power efficiency of QFPM and CP QFPM on the AWGN (additive white Gaussian noise) channel is always superior when compared to that of quadrature-amplitude modulation (QAM), and their bandwidth efficiency is demonstrated to be under certain conditions comparable or better than that of QAM. Both schemes possess a self-synchronization capability. The demonstrated performance characteristics of QFPM and CP QFPM suggest that they may be competitive with respect to QAM on channels where little or no filtering is desired.>

A new modulation scheme that produces a constant envelope continuous phase signal set with a compact power spectrum and power efficiency better than that of MSK is proposed. The scheme can be implemented by quadrature-carrier multiplexing of two frequency/phase modulated signals of the type NFSK/2PSK, both with the same frequency in each transmission interval, and with sinusoidal symbol shapes. The generated signal can be viewed in each transmission interval as an MSK signal at one of the N frequencies and is referred to as multifrequency minimum shift keying (MF MSK). Modulation, demodulation, and synchronization circuits are described, and the spectral properties and power efficiency on the AWGN channel are analyzed. Combining a number of attractive attributes such as constant envelope, excellent spectral properties, high power efficiency, and self-synchronization capability, the proposed modulation format lends itself to a variety of applications, one of them being the digital satellite link.>