A hybrid fiber/wireless link based on a single visible LED and free of opto-electronic intermediate conversion stages has been demonstrated for indoor communications. This paper shows the main guidelines proper coupling in fiber/air/detector interfaces. Experimental demonstration validated design results with very good agreement between geometrical optics simulation received optical power measu...

Nowadays, mobile radio communication systems are mainly affected by frequency and time selective radio channel due to multipath propagation and Doppler shifts. For combating these two effects of radio channels, an OFDM based system that is with fixed and adaptive order QAM schemes and TFL-CDMA technique will be described and studied in this thesis. OFDM technique can remove the inter-symbol-int...

where p(t) is a (typically real valued) pulse shape, and the ck are QAM symbols drawn from a finite collection of complex numbers called a constellation based on input bits to be communicated over the channel. Some example QAM constellations include 4-QAM (a.k.a QPSK){±1± j}, 16-QAM {±a± jb} with a, b ∈ {1, 3}, 64-QAM {±a + jb} with a, b ∈ {1, 3, 5, 7}, and 256-QAM {±a ± jb} with a, b ∈ {1, 3, ...

In this work performance of Gaussian Minimum Shift Keying (GMSK) modulation is compared with that of conventional QPSK and M-QAM modulation schemes. Use of unfiltered data stream for modulation results in a considerably large bandwidth in the modulated RF signal. Pulse shaping as a signal processing technique has gain grounds as a means to mitigate this problem. Gaussian filter along with squar...

In this paper, we have measured channel capacity for various communication system such as SISO, SIMO, MIMO with different modulation technique like BPSK, QPSK, 16-QAM and 64-QAM. In the proposed algorithm the Bit Error Rate (BER) is less compared to conventional algorithm. The proposed algorithm is suitable for fast speed traffic that is when the speed of the mobile is very high. We have measur...

We report a multi–dimensional quadrature amplitude modulation with M-ary differential phase shift keying (QAM-MDPSK) for optical access network transmission systems employing Mach–Zehnder modulator (MZM) and (PM) in direct detection system. Even though several problems that occur QAM-DPSK single MZM were solved, inter-signal distortion between two modulations remains when the signal is converte...

Faster-than-Nyquist (FTN) signaling is a promising non-orthogonal pulse modulation technique that can improve the spectral efficiency (SE) of next generation communication systems at expense higher detection complexity to remove introduced inter-symbol interference (ISI). In this paper, we investigate problem ultra high-order quadrature-amplitude (QAM) FTN where exploit mathematical programming...

|Home Phoneline Networking Alliance (HomePNA) 2.0 is a promising new technology using existing telephone wiring for home networking. A key feature of its transmission standard is to provide several physical layer modes, with di erent modulation formats at two possible symbol rates, which can be selected according to the channel conditions. In particular at the lower symbol rate it employs a mod...

Adaptive modulation system is one of the key techniques in building a broadband mobile communication network because of increasing shortage of wireless communication channels. Quadrature amplitude modulation (QAM) has been widely used in adaptive modulation because of its efficiency in power and bandwidth. To better understand the QAM system, a Simulink-based simulation system is designed. In t...

A class of circular 64-QAM that combines ‘geometric’ and ‘probabilistic’ shaping aspects is presented. It is compared to square 64-QAM in back-to-back, single-channel, and WDM transmission experiments. First, for the linear AWGN channel model, it permits to operate close to the Shannon limits for a wide range of signal-to-noise ratios. Second, WDM simulations over several hundreds of kilometers...