Generalized Space Shift Keying Research Articles

Improved Generalized Space-Shift Keying via Power Allocation

We investigate the power allocation in generalized space-shift keying (GSSK) multiple-input-multiple-output (MIMO) systems. The maximum-likelihood detection with full channel state information (CSI) at the receiver is considered. The goal of the design is to allocate transmit power on GSSK antennas to minimize the symbol error rate (SER) under the total power constraint. An upper bound of SER conditioned on CSI is presented. We propose an algorithm, called the Euclidean distance-based power allocation scheme, to minimize the SER upper bound. Simulation results demonstrate the performance superiority in the proposed scheme compared with prior space-shift-keying-type schemes and the conventional MIMO schemes.

Demonstration of the Merit and Limitation of Generalised Space Shift Keying for Indoor Visible Light Communications

This paper demonstrates the merit and de-merit of a low complexity, multiple transmitter generalised space shift keying (GSSK) signalling technique for short range indoor visible light communications. To illustrate the high spectral efficiency credential of GSSK, an array of Nt white light emitting diodes (LEDs) is used to demonstrate Nt bits/symbol transmission by exploiting the natural differences in the channel gains of the spatially separated LED array. With two low power white LEDs each having a 3 dB modulation bandwidth of 8 MHz, data transmission of up to 40 Mbits/s ( 20 Mbaud) is demonstrated. For an average received electrical signal power of -12.5 dBm and 2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> data symbols, the measured symbol error rate at 20 Mbaud is 7 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> and 5 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> at 10 Mbaud ( 20 Mbits/s) without any error control coding. The GSSK technique is experimentally shown to be most suitable for a fixed configuration as its performance is quite sensitive to receiver mobility.

Hierarchical Multilevel Space-Shift Keying for Unequal Error Protection under Rician Fading

Hierarchical Multilevel Space-Shift Keying Modulation is proposed for Unequal Error Protection under Line-Of Sight conditions in Rician fading channels. The High Priority (HP) information is conveyed via the number of active antennas employed to transmit a codeword. The Low Priority (LP) information is transmitted employing Generalized Space Shift Keying (GSSK) in the codeword subsets corresponding to the transmission of the HP symbols. Hierarchical modulation is accomplished by associating phase shifts with every transmit antenna and adjusting these phase shifts to achieve different levels of Unequal Error Protection. The simulations demonstrate the performance and design options offered by the proposed scheme.

A method for the construction of hierarchical generalized space shift keying (GSSK) modulation for unequal error protection

In this paper, we propose a systematic method to achieve two-level unequal error protection (UEP) with generalized space shift keying (GSSK) modulation for multiple-input multiple-output (MIMO) systems. GSSK is a modulation scheme that encodes the source information in the antenna indices. To enable the nonuniform arrangement of the spatial constellation of GSSK modulation, new techniques are needed as new features of GSSK modulation are observed. The proposed method is based on first partitioning the GSSK constellation into subsets and then choosing constellation points inside a subset. The high-priority (HP) bits select the subset and the low-priority (LP) bits select constellation points inside a subset. The proposed subset partitioning procedure developed based on a theoretical study on set partitioning in the multidimensional space guarantees optimal or near-optimal HP protection, enables simple and systematic designs for LP protection, and increases the LP capacity. The proposed systematic design approach applies to systems with any numbers of transmit antennas and can create various hierarchical GSSK schemes with different HP/LP protection capabilities.

Error Performance of Generalised Space Shift Keying for Indoor Visible Light Communications

In this paper the error performance analysis of a low complexity, multiple transmitter generalised space shift keying (GSSK) signalling technique for short range indoor visible light communications is presented. In an N_t transmitter system, this signalling technique is capable of achieving a spectral efficiency of N_t bits/s/Hz. The GSSK system has a higher spectral efficiency than the conventional on-off keying (OOK) and pulse position modulation (PPM) techniques. The GSSK transmitter is much simpler than that of an equivalent regular pulse amplitude modulation (PAM) system with similar spectral efficiency. An analytical expression for the symbol error rate (SER) is presented and verified using simulations. The receiver is based on the maximum likelihood criterion and using multiple photodetectors (PDs) in the receiver improves the error performance. Within the room and the transmitter-receiver configuration under consideration, with four PDs, a gain of 6 dB is attainable over the single PD system for the case of 2 and 3 bits/s/Hz. Considering a fixed link range with N_t = 2 and at a symbol error rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> , using wide half angle LEDs with Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sub> = 60° requires about 12 dB less in electrical signal-to-noise ratio compared with Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sub> = 30°. The beam directivity is however of much lower effect when the room under consideration is equiped with sufficient LEDs to provide full coverage. The GSSK technique can also support dimming control by using different pulse widths. This, however, is at a price of reduced spectral efficiency.

Adaptive generalized space shift keying

In this article, we propose a closed-loop precoding method for the Generalized Space Shift Keying (GSSK) modulation scheme, suitable for Multiple-Input-Single-Output (MISO) systems and denoted as adaptive GSSK (AGSSK), which achieves transmit-diversity gains in contrast to GSSK. For the case of a perfect feedback channel, we analytically show that for three and four antennas at the transmitter and rates 1 and 2 bits per channel use (bpcu), respectively, a full transmit-diversity can be achieved without reducing the achievable rate. For higher number of transmit antennas and rates, the performance of the proposed scheme degrades due to the smaller average minimum Euclidean distance as the rate increases. Due to this, we, furthermore, propose an enhancing method for AGSSK which relies on the use of time-orthogonal shaping filters for the different constellation points. For the enhanced method, named as AGSSK with time-orthogonal signal design (AGSSK-TOSD), we analytically prove that it offers transmit-diversity gains which are greater than the number of active transmit antennas for any number of transmit antennas and supported rate. This is attained without any antenna subset selection technique, which alleviates the processing burden on the terminal side. Monte Carlo simulations show that AGSSK significantly outperforms GSSK in terms of average bit error probability (ABEP) and, moreover, for medium to high rates and practical signal-to-noise ratio (SNR) regions AGSSK-TOSD outperforms well-known feedback-based multiple-antenna schemes. This advantage of AGSSK-TOSD is further substantiated with an energy effficiency comparison over the conventional schemes for a target (uncoded) ABEP.

Bi-Space Shift Keying Modulation for MIMO Systems

In this letter, we propose a new Space Shift Keying (SSK)-based modulation that maps the information onto the antenna indices. The proposed Bi-Space Shift Keying (BiSSK) scheme extends SSK by employing a dual set of antenna indices, one associated with a real number and the other with an imaginary number. The proposed BiSSK preserves the advantages of low receiver complexity of SSK and yet doubles its transmission rates, with negligible performance penalty. The proposed BiSSK outperforms Generalized Space Shift Keying (GSSK) at the same given target transmission rate, as demonstrated by both error-probability analyses and simulations.