Browsing by Author "Basar, Ertugrul"

Now showing 1 - 13 of 13

Citation Count: 9
Interpolation Based Pilot-Aided Channel Estimation for STBC Spatial Modulation and Performance Analysis Under Imperfect CSI
(Inst Engineering Technology-IET, 2016) Panayırcı, Erdal; Dogan, Hakan; Basar, Ertugrul; Panayırcı, Erdal
A combination of space-time block coding and spatial modulation (STBC-SM) has been recently proposed for multiple input-multiple output systems to obtain both spatial diversity gain and more capacity simultaneously while assuming the perfect channel state information (P-CSI) was available at the receiver. However in practical scenarios the CSI is unknown to the receiver and should be estimated in order to detect the transmitted data in a reliable way. Therefore channel estimation (CE) is a major challenge in designing the STBC-SM systems. In this study the problem of CE is investigated and a new pilot-aided channel estimation (PA-CE) technique coupled with an interpolation is proposed for the STBC-SM systems operating in the presence of rapidly time-varying mobile channels. Several interpolation schemes such as the linear nearest neighbour piecewise cubic Hermite and the low-pass interpolations are applied and their performances are compared to determine the best suitable interpolation technique to be employed in STBC-SM systems. Bit error rate (BER) performance of the proposed CE technique is then investigated in time-varying channels with different modulation. Moreover the pairwise error probability of the STBC-SM scheme is derived and its average bit error probability is evaluated analytically in the presence of CE errors.
Citation Count: 79
New Trellis Code Design for Spatial Modulation
(IEEE-INST Electrical Electronics Engineers Inc, 2011) Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
Spatial modulation (SM) in which multiple antennas are used to convey information besides the conventional M-ary signal constellations is a new multiple-input multiple-output (MIMO) transmission technique which has recently been proposed as an alternative to V-BLAST (vertical Bell Labs layered space-time). In this paper a novel MIMO transmission scheme called spatial modulation with trellis coding (SM-TC) is proposed. Similar to the conventional trellis coded modulation (TCM) in this scheme a trellis encoder and an SM mapper are jointly designed to take advantage of the benefits of both. A soft decision Viterbi decoder which is fed with the soft information supplied by the optimal SM decoder is used at the receiver. A pairwise error probability (PEP) upper bound is derived for the SM-TC scheme in uncorrelated quasi-static Rayleigh fading channels. From the PEP upper bound code design criteria are given and then used to obtain new 4- 8- and 16-state SM-TC schemes using quadrature phase-shift keying (QPSK) and 8-ary phase-shift keying (8-PSK) modulations for 2 3 and 4 bits/s/Hz spectral efficiencies. It is shown via computer simulations and also supported by a theoretical error performance analysis that the proposed SM-TC schemes achieve significantly better error performance than the classical space-time trellis codes and coded V-BLAST systems at the same spectral efficiency yet with reduced decoding complexity.
Citation Count: 92
Optical MIMO-OFDM With Generalized LED Index Modulation
(IEEE-INST Electrical Electronics Engineers Inc, 2017) Yeşilkaya, Anıl; Basar, Ertugrul; Miramirkhani, Farshad; Panayırcı, Erdal; Uysal, Murat; Haas, Harald
Visible light communications (VLC) is a promising and uncharted new technology for the next generation of wireless communication systems. This paper proposes a novel generalized light emitting diode (LED) index modulation method for multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM)-based VLC systems. The proposed scheme avoids the typical spectrum efficiency losses incurred by time- and frequency-domain shaping in OFDM signals. This is achieved by exploiting spatial multiplexing along with LED index modulation. Accordingly real and imaginary components of the complex time-domain OFDM signals are separated first then resulting bipolar signals are transmitted over a VLC channel by encoding sign information in LED indexes. As a benchmark we demonstrate the performance analysis of our proposed system for both analytical and physical channel models. Furthermore two novel receiver designs are proposed. Each one is suitable for frequency-flat or selective channel scenarios. It has been shown via extensive computer simulations that the proposed scheme achieves considerably better bit error ratio versus signal-to-noise-ratio performance than the existing VLC-MIMO-OFDM systems that use the same number of transmit and receive units [LEDs and photo diodes (PDs)]. Compared with the single-input single-output (SISO) DC biased optical (DCO)-OFDM system both spectral efficiency and DC bias can be doubled and removed respectively simply by exploiting a MIMO configuration.
Citation Count: 48
Optical OFDM with index modulation for visible light communications
(Institute of Electrical and Electronics Engineers Inc., 2015) Panayırcı, Erdal; Panayırcı, Erdal
In this paper we propose optical orthogonal frequency division multiplexing with index modulation (O-OFDM-IM) for visible light communications (VLC) systems employing light emitting diodes (LEDs) and photodetectors (PDs). The proposed scheme uses the indices of the active subcarriers of an optical OFDM system to transmit additional information bits. In the proposed scheme the bipolar signals are asymmetrically clipped or DC biased and a log-likelihood ratio (LLR) calculation based detector is used to determine the indices of the active subcarriers. Our computer simulations show that the O-OFDM-IM achieves better error peformance compared to classical optical OFDM schemes. © 2015 IEEE.
Citation Count: 53
Optical OFDM with Index Modulation for Visible Light Communications
(Ieee, 2015) Panayırcı, Erdal; Panayirci, Erdal
In this paper, we propose optical orthogonal frequency division multiplexing with index modulation (O-OFDM-IM) for visible light communications (VLC) systems employing light emitting diodes (LEDs) and photodetectors (PDs). The proposed scheme uses the indices of the active subcarriers of an optical OFDM system to transmit additional information bits. In the proposed scheme, the bipolar signals are asymmetrically clipped or DC biased and a log-likelihood ratio (LLR) calculation based detector is used to determine the indices of the active subcarriers. Our computer simulations show that the O-OFDM-IM achieves better error peformance compared to classical optical OFDM schemes.
Citation Count: 1
Optical Spatial Modulation OFDM System Design [Optik Uzaysal Modülasyonlu OFDM Sistem Tasarımı]
(Institute of Electrical and Electronics Engineers Inc., 2016) Panayırcı, Erdal; Basar, Ertugrul; Panayırcı, Erdal
In this paper a new optical orthogonal frequency division multiplexing (OFDM) method is proposed for multiple-input multiple-output (MIMO) visible light communications (VLC) systems. In the new scheme non-DC biased optical OFDM (NDC-OFDM) and optical spatial modulation (OSM) methods are combined to obtain a novel optical OFDM scheme which has a better error performance. The new scheme is named as non-DC biased optical spatial modulation OFDM (NDC-OSM-OFDM). It is shown via computer simulations that the proposed scheme achieves better bit error rate (BER) performance than DC-biased optical spatial modulation OFDM (OSM-OFDM-DC) asymmetrically clipped optical spatial modulation OFDM (OSM-OFDM-AC) and NDC-OFDM. © 2016 IEEE.
Citation Count: 34
Orthogonal frequency division multiplexing with index modulation in the presence of high mobility
(2013) Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, Erdal
In this paper a novel orthogonal frequency division multiplexing (OFDM) scheme which is called OFDM with index modulation (OFDM-IM) is proposed for frequency-selective fading channels in the presence of high mobility. In this scheme inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels the information is conveyed not only by M-ary signal constellations as in classical OFDM but also by the indices of the subcarriers which are activated according to the incoming bit stream. Different low complexity transceiver structures based on maximum likelihood (ML) detection or log-likelihood ratio (LLR) calculation are proposed. It is shown via computer simulations that the proposed scheme achieves significantly better error performance than classical OFDM. © 2013 IEEE.
Citation Count: 31
Orthogonal Frequency Division Multiplexing with Index Modulation in the Presence of High Mobility
(Ieee, 2013) Panayırcı, Erdal; Aygolu, Umit; Panayirci, Erdal
In this paper, a novel orthogonal frequency division multiplexing (OFDM) scheme, which is called OFDM with index modulation (OFDM-IM), is proposed for frequency-selective fading channels in the presence of high mobility. In this scheme, inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels, the information is conveyed not only by M-ary signal constellations as in classical OFDM, but also by the indices of the subcarriers, which are activated according to the incoming bit stream. Different low complexity transceiver structures based on maximum likelihood (ML) detection or log-likelihood ratio (LLR) calculation are proposed. It is shown via computer simulations that the proposed scheme achieves significantly better error performance than classical OFDM.
Citation Count: 0
Performance of MIMO Enhanced Unipolar OFDM With Realistic Indoor Visible Light Channel Models
(Institute of Electrical and Electronics Engineers Inc., 2016) Yeşilkaya, Anıl; Miramirkhani, Farshad; Basar, Ertugrul; Panayırcı, Erdal; Uysal, Murat
Visible light communication (VLC) involves the dual use of illumination infrastructure for high speed wireless access. Designing such optical based communication systems realistic indoor optical channel modeling becomes an important issue to be handled. In this paper first we obtain new realistic indoor VL channel characterizations and models in a multiple-input multiple-output (MIMO) transmission scenario using non-sequential ray tracing approach for the channel impulse responses (CIRs). Practical issues such as number of light emitting diode (LED) chips per luminary spacing between LED chips objects inside the room and cabling topology are also investigated. On the other hand since indoor optical channels exhibit frequency selectivity multi-carrier communication systems particularly orthogonal frequency division multiplexing (OFDM) is used to handle the resulting inter-symbol interference in VLC systems. Hence we propose a new MIMO-OFDM based VLC system called MIMO enhanced unipolar OFDM (MIMO-eU-OFDM) by combining MIMO transmission techniques with the recently proposed eU-OFDM scheme. The bit error rate (BER) performance of the proposed system is investigated in the presence of the 2×2 and 4×4 realistic MIMO VLC channels and its BER performance is compared with the reference optical MIMO-OFDM systems. © 2016 IEEE.
Citation Count: 2
Reliable two-path successive relaying
(2013) Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
Emerging two-path successive relaying protocols generally rely on error-free source-relay channels and/or interference-free inter-relay channels to achieve high-rate and full-diversity. In this paper by removing these optimistic assumptions a novel two-path successive relaying scheme that benefits from relay selection and distributed space-time block coding (STBC) and transfers the data from the source to the destination via relays in a reliable fashion is proposed. The proposed scheme can achieve full diversity without the requirement of perfect decoding at relays since not only the destination but also the relays benefit from distributed STBC and relay selection. As the target STBC coordinate interleaved orthogonal design (CIOD) for two transmit antennas is considered. The average symbol error probability of the proposed scheme is derived and its error performance is compared with reference systems. © 2013 IEEE.
Citation Count: 15
Super-orthogonal trellis-coded spatial modulation
(Inst Engineering Technology-IET, 2012) Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
Spatial modulation (SM) which employs the indices of multiple transmit antennas to transmit information in addition to the conventional M-ary signal constellations is a novel transmission technique that has been proposed for multiple-input multiple-output systems. In this study a new class of space-time trellis codes called 'super-orthogonal trellis-coded SM' (SOTC-SM) is proposed. These codes combine set partitioning and a super set of space-time block coded SM (STBC-SM) codewords to achieve maximal diversity and coding gains by exploiting both SM and space-time block codes. Unlike super-orthogonal space-time trellis codes (SOSTTCs) which parametrise the orthogonal STBCs these new codes expand the antenna constellation using the principle of SM. Systematic construction methods are presented for the SOTC-SM scheme and design examples are given for 2 4 and 8 trellis states at 2 3 and 4 bits/s/Hz spectral efficiencies. The approximate bit-error probability performance of SOTC-SM is derived and shown to match computer simulation results. A simplified maximum likelihood detection method for the proposed scheme is given. It is shown through computer simulations that the proposed SOTC-SM schemes achieve significantly better error performance than SOSTTCs with comparable complexity.
Citation Count: 2
Trellis Code Design for Spatial Modulation
(Ieee, 2011) Panayırcı, Erdal; Aygolu, Umit; Panayirci, Erdal
In this paper, we propose a novel multiple-input multiple-output (MIMO) transmission scheme, called trellis coded spatial modulation (TC-SM) in which a trellis (convolutional) encoder and a spatial modulation (SM) mapper are jointly designed similar to the conventional trellis coded modulation (TCM). A soft decision Viterbi decoder, which is fed with the soft information supplied by the optimal SM decoder, is used at the receiver. The pairwise error probability (PEP) upper bound is derived for the TC-SM scheme in uncorrelated quasi-static Rayleigh fading channels. From the PEP upper bound, code design criteria are given and then used to obtain new 4-, 8- and 16-state TC-SM schemes using QPSK (quadrature phase-shift keying) and 8-PSK modulations for 2 and 3 bits/s/Hz spectral efficiencies. It is shown via computer simulations that the proposed TC-SM schemes achieve significantly better error performance than their counterparts at the same spectral efficiency, yet with reduced decoding complexity.
Citation Count: 0
Trellis coding for spatial modulation [Uzaysal modulasyon i?çi?n kafes kodlama]
(2011) Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
In this study by combining trellis coding with spatial modulation (SM) a new multiple-input multiple output (MIMO) communication scheme called trellis coded spatial modulation (TC-SM) is proposed. For uncorrelated Rayleigh fading channels code design criteria are given by deriving pairwise error probability (PEP) of this system in which a trellis encoder and SM mapper are jointly designed. These criteria are then used to obtain 4 8 and 16-states TC-SM schemes. It is shown via computer simulations that the proposed TC-SM schemes achieve better error performance than the classical space-time trellis codes with reduced decoder complexity. © 2011 IEEE.