78 research outputs found
Space shift keying modulation for MIMO channels
In this thesis, we analyze modulation techniques that exploit multiple antennas in wireless communication. We first study the so-called spatial modulation (SM) technique for MIMO channels. Since the original SM detector is based on an ad hoc design, and only functions under some artificial assumptions about the channel, we derive the optimal detector for SM. The new detector performs significantly better than the original ({598} 4 dB gain), and we support our results by deriving a closed form expression for the average bit error probability. As well, we show that SM with the optimal detector achieves better performance gains ({598}1.5 - 3 dB) over popular multiple antenna systems. We then introduce space shift keying (SSK), a new modulation scheme based on the SM concept. SSK exploits fading in multiple input multiple output (MIMO) channels to provide better performance over conventional amplitude/phase modulation (APM) techniques. In SSK, only the antenna indices, and not the symbols themselves, relay information. This absence of symbol information eliminates the transceiver elements necessary for APM transmission and detection (such as coherent detectors). As well, the simplicity involved in modulation reduces detection complexity compared to that of SM, while achieving almost identical performance gains. Throughout the thesis, we illustrate SSK's strength by studying its interaction with the fading channel, and obtain tight upper bounds on bit error probability. To improve performance, adaptive forms of SSK are also presented, including a symbol design technique, and an antenna selection scheme. We also illustrate SSK's performance under channel estimation error, and spatial correlation. Analytical and simulation results show performance gains over APM systems (3 dB at a bit error rate of 10 -5 ), making SSK an interesting candidate for wireless applications. We then present SSK coded modulation (SSK-CM) to integrate coding for practical wireless systems. In particular, we present a bit interleaved CM (BICM) system using iterative decoding. We illustrate SSK-CM capacity improvements over APM, and derive upper bounds on SSK-CM's performance. We also analytically present SSK's coded diversity advantage over APM, where significant performance gains are observed (up to 9 dB), motivating SSK-CM's integration in future wireless standard
Improved Spatial Modulation for High Spectral Efficiency
Spatial Modulation (SM) is a technique that can enhance the capacity of MIMO
schemes by exploiting the index of transmit antenna to convey information bits.
In this paper, we describe this technique, and present a new MIMO transmission
scheme that combines SM and spatial multiplexing. In the basic form of SM, only
one out of MT available antennas is selected for transmission in any given
symbol interval. We propose to use more than one antenna to transmit several
symbols simultaneously. This would increase the spectral efficiency. At the
receiver, an optimal detector is employed to jointly estimate the transmitted
symbols as well as the index of the active transmit antennas. In this paper we
evaluate the performance of this scheme in an uncorrelated Rayleigh fading
channel. The simulations results show that the proposed scheme outperforms the
optimal SM and V-BLAST (Vertical Bell Laboratories Layered space-time at high
signal-to-noise ratio (SNR). For example, if we seek a spectral efficiency of 8
bits/s/Hz at bit error rate (BER) of 10^-5, the proposed scheme provides 5dB
and 7dB improvements over SM and V-BLAST, respectively.Comment: 7 pages, 4 figures, 1 table, International Journal of Distributed and
Parallel Systems (IJDPS) Vol.3, No.2, March 201
Media-Based MIMO: A New Frontier in Wireless Communications
The idea of Media-based Modulation (MBM), is based on embedding information
in the variations of the transmission media (channel state). This is in
contrast to legacy wireless systems where data is embedded in a Radio Frequency
(RF) source prior to the transmit antenna. MBM offers several advantages vs.
legacy systems, including "additivity of information over multiple receive
antennas", and "inherent diversity over a static fading channel". MBM is
particularly suitable for transmitting high data rates using a single transmit
and multiple receive antennas (Single Input-Multiple Output Media-Based
Modulation, or SIMO-MBM). However, complexity issues limit the amount of data
that can be embedded in the channel state using a single transmit unit. To
address this shortcoming, the current article introduces the idea of Layered
Multiple Input-Multiple Output Media-Based Modulation (LMIMO-MBM). Relying on a
layered structure, LMIMO-MBM can significantly reduce both hardware and
algorithmic complexities, as well as the training overhead, vs. SIMO-MBM.
Simulation results show excellent performance in terms of Symbol Error Rate
(SER) vs. Signal-to-Noise Ratio (SNR). For example, a LMIMO-MBM is
capable of transmitting bits of information per (complex) channel-use,
with SER at dB (or SER
at dB). This performance is achieved using a single transmission
and without adding any redundancy for Forward-Error-Correction (FEC). This
means, in addition to its excellent SER vs. energy/rate performance, MBM
relaxes the need for complex FEC structures, and thereby minimizes the
transmission delay. Overall, LMIMO-MBM provides a promising alternative to MIMO
and Massive MIMO for the realization of 5G wireless networks.Comment: 26 pages, 11 figures, additional examples are given to further
explain the idea of Media-Based Modulation. Capacity figure adde
Energy Efficient Transmission over Space Shift Keying Modulated MIMO Channels
Energy-efficient communication using a class of spatial modulation (SM) that
encodes the source information entirely in the antenna indices is considered in
this paper. The energy-efficient modulation design is formulated as a convex
optimization problem, where minimum achievable average symbol power consumption
is derived with rate, performance, and hardware constraints. The theoretical
result bounds any modulation scheme of this class, and encompasses the existing
space shift keying (SSK), generalized SSK (GSSK), and Hamming code-aided SSK
(HSSK) schemes as special cases. The theoretical optimum is achieved by the
proposed practical energy-efficient HSSK (EE-HSSK) scheme that incorporates a
novel use of the Hamming code and Huffman code techniques in the alphabet and
bit-mapping designs. Experimental studies demonstrate that EE-HSSK
significantly outperforms existing schemes in achieving near-optimal energy
efficiency. An analytical exposition of key properties of the existing GSSK
(including SSK) modulation that motivates a fundamental consideration for the
proposed energy-efficient modulation design is also provided
Space-Time-Frequency Shift Keying for Dispersive Channels
Inspired by the concept of the Space-Time Shift Keying (STSK) modulation, in this paper we proposed the Space-Frequency Shift Keying (SFSK) modulation as well as the Space-Time-Frequency Shift Keying (STFSK) concept which spreads the transmit signal not only across the space and time domains, but also the frequency domain. The performance of STSK modulation is degraded by about 2 dB, when the channel changes from uncorrelated frequency-flat fading to the frequency-selective environment of the 6-tap COST207 model. By contrast, as a benefit of Frequency Shift keying, the SFSK and STFSK schemes are capable of maintaining their performance also in frequency-selective fading environments. Finally, we demonstrate that the STSK and SFSK schemes constitute special cases of the STFSK modulatio
Structured Dispersion Matrices From Division Algebra Codes for Space-Time Shift Keying
We propose a novel method of constructing Dispersion Matrices (DM) for Coherent Space-Time Shift Keying (CSTSK) relying on arbitrary PSK signal sets by exploiting codes from division algebras. We show that classic codes from Cyclic Division Algebras (CDA) may be interpreted as DMs conceived for PSK signal sets. Hence various benefits of CDA codes such as their ability to achieve full diversity are inherited by CSTSK. We demonstrate that the proposed CDA based DMs are capable of achieving a lower symbol error ratio than the existing DMs generated using the capacity as their optimization objective function for both perfect and imperfect channel estimation
Quadrature Spatial Modulation Orthogonal Frequency Division Multiplexing
This paper investigates the application of quadrature spatial modulation (QSM) to orthogonal frequency division multiplexing (OFDM). In comparison to spatial modulation OFDM (SM-OFDM), the proposed QSM-OFDM achieves an enhanced spectral efficiency by decomposing the amplitude and/or phase modulated signal into its real and imaginary components as the transmitted symbols. The index/indices of the activated transmit antenna(s) are employed to convey additional information. These symbols are transmitted orthogonally to eliminate inter-channel interference with little trade-off in synchronization. The average bit error probability for QSM-OFDM and other schemes, including the SM-OFDM, conventional multiple-input multiple-output (MIMO-OFDM), maximal-ratio combining single-input multiple-output (MRC-OFDM), vertical Bell Laboratories layered space-time architecture (VBLAST-OFDM) and Alamouti-OFDM systems are demonstrated using Monte Carlo simulation. The expressions for the receiver computational complexities in terms of the number of real operations are further derived. QSM-OFDM yields a significant signal-to-noise ratio gain of dB with little trade-off in computational complexity over SM-OFDM, while substantial gains greater than dB are evident, when compared to other systems
Introduction to Generalised Spatial Modulation
In this paper generalized spatial modulation technique is introduced. This is a new technique for MIMO system. It enhances the spectral efficiency and reduces BER. GSM enhances the system performance
Complex Quadrature Spatial Modulation
In this paper, we propose a spatial modulation (SM) scheme referred to as
complex quadrature spatial modulation (CQSM). In contrast to quadrature spatial
modulation (QSM), CQSM transmits two complex signal constellation symbols on
the real and quadrature spatial dimensions at each channel use, increasing the
spectral efficiency. To this end, signal symbols transmitted at any given time
instant are drawn from two different modulation sets. The first modulation set
is any of the conventional QAM/PSK alphabets, while the second is a rotated
version of it. The optimal rotation angle is obtained through simulations for
several modulation schemes and analytically proven for the case of QPSK, where
both results coincide. Simulation results showed that CQSM outperformed QSM and
generalized SM (GSM) by approximately 5 and 4.5 dB, respectively, for the same
transmission rate. Its performance was similar to that of QSM; however, it
achieved higher transmission rates. It was additionally shown numerically and
analytically that CQSM outperformed QSM for a relatively large number of
transmit antennas.Comment: 11 pages, 3 tables, 11 figures. ETRI Journal, 201
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