Browsing by Author "Aygölü, Ümit"

Now showing 1 - 12 of 12

Citation Count: 0
Design and performance analysis of a novel trellis coded space-time-frequency OFDM transmission scheme
(Wiley-Blackwell, 2008) Oğuz, Onur; Aygölü, Ümit; Panayırcı, Erdal
In this paper a new transmit diversity technique is proposed for wireless communications over frequency selective fading channels. The proposed technique utilises orthogonal frequency division multiplexing (OFDM) to transform a frequency selective fading channel into multiple flat fading subchannels on which first space-frequency coding and then additional space-time coding are applied resulting in a space-time-frequency OFDM (STF-OFDM) scheme. This scheme provides a quasi-orthogonal 4 x 4 transmission matrix but relax the constraint on channel fading parameters to be constant over four time or frequency slots into two time and two frequency slots. The pairwise error probability of the new scheme is evaluated and new code design criteria are obtained to improve the error performance. 64- 128- and 256-state 4-PSK trellis codes for STF transmission scheme are generated based on these criteria and their frame error performances in an OFDM system are evaluated by computer simulations. Copyright (c) 2007 John Wiley & Sons Ltd.
Citation Count: 1
A New Technique for OFDM: OFDM-Index Modulation
(IEEE, 2013) Basar, Ertuğrul; Aygölü, Ümit; Panayırcı, Erdal
In this study a novel scheme called orthogonal frequency division multiplexing with index modulation (OFDMIM) is proposed for frequency selective channels. In this scheme the information is conveyed not only by only M -ary signal constellations as in classical OFDM but also by the indices of the active subcarriers which are determined according to the information bits. Different transceiver structures have been investigated for the proposed scheme and it has been shown via computer simulations that OFDM-IM system achieves significantly better error performance than the classical OFDM.
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: 734
Orthogonal Frequency Division Multiplexing With Index Modulation
(IEEE-INST Electrical Electronics Engineers Inc, 2013) Başar, Ertuğrul; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
In this paper a novel orthogonal frequency division multiplexing (OFDM) scheme called OFDM with index modulation (OFDM-IM) is proposed for operation over frequency-selective and rapidly time-varying fading channels. In this scheme 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 detection or log-likelihood ratio calculation are proposed and a theoretical error performance analysis is provided for the new scheme operating under ideal channel conditions. Then the proposed scheme is adapted to realistic channel conditions such as imperfect channel state information and very high mobility cases by modifying the receiver structure. The approximate pairwise error probability of OFDM-IM is derived under channel estimation errors. For themobility case several interference unaware/aware detection methods are proposed for the new scheme. It is shown via computer simulations that the proposed scheme achieves significantly better error performance than classical OFDM due to the information bits carried by the indices of OFDM subcarriers under both ideal and realistic channel conditions.
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: 135
Performance of spatial modulation in the presence of channel estimation errors
(IEEE-INST Electrical Electronics Engineers Inc, 2012) Basar, Ertuğrul; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
This work investigates the negative effects of channel estimation errors on the performance of spatial modulation (SM) when operating over flat Rayleigh fading channels. The pairwise error probability of the SM scheme is derived in the presence of channel estimation errors and an upper bound on the average bit error probability is evaluated for M-PSK and M-QAM signalling. It is shown via computer simulations that the derived upper bound becomes very tight with increasing signal-to-noise ratio (SNR) and the SM scheme is quite robust to channel estimation errors.
Citation Count: 11
A Reliable Successive Relaying Protocol
(IEEE-INST Electrical Electronics Engineers Inc, 2014) Panayırcı, Erdal; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
Successive relaying has recently emerged as an effective technique for cooperative networks and provides significant improvements in bandwidth efficiency over traditional relaying techniques ;however to achieve full-diversity the available successive relaying protocols generally assume noise-free sourcerelay and interference-free inter-relay channels. In this paper a novel successive relaying protocol is proposed for N-relay wireless networks by removing these optimistic assumptions. The proposed protocol benefits from distributed space-time block codes (STBCs) with coordinate interleaving and relay selection. It achieves a diversity order of two and high transmission rate under realistic network conditions with single-symbol maximum likelihood (ML) detection. A general N-relay signaling protocol is presented and specific design examples are given for N = 2 3 and 4-relay cooperative networks. The average symbol error probability (ASEP) is analytically derived and shown to match with computer simulation results. It is also shown via computer simulations that the proposed scheme achieves significantly better error performance and is more robust to channel estimation errors than its counterparts given in the literature under realistic network conditions.
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: 310
Space-Time Block Coded Spatial Modulation
(IEEE-INST Electrical Electronics Engineers Inc, 2011) Başar, Ertuğrul; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
A novel multiple-input multiple-output (MIMO) transmission scheme called space-time block coded spatial modulation (STBC-SM) is proposed. It combines spatial modulation (SM) and space-time block coding (STBC) to take advantage of the benefits of both while avoiding their drawbacks. In the STBC-SM scheme the transmitted information symbols are expanded not only to the space and time domains but also to the spatial (antenna) domain which corresponds to the on/off status of the transmit antennas available at the space domain and therefore both core STBC and antenna indices carry information. A general technique is presented for the design of the STBC-SM scheme for any number of transmit antennas. Besides the high spectral efficiency advantage provided by the antenna domain the proposed scheme is also optimized by deriving its diversity and coding gains to exploit the diversity advantage of STBC. A low-complexity maximum likelihood (ML) decoder is given for the new scheme which profits from the orthogonality of the core STBC. The performance advantages of the STBC-SM over simple SM and over V-BLAST are shown by simulation results for various spectral efficiencies and are supported by the derivation of a closed form expression for the union bound on the bit error probability.
Citation Count: 11
Space-Time Block Coding for Spatial Modulation
(IEEE, 2010) Başar, Ertuğrul; Aygölü, Ümit; Panayırcı, Erdal; Poor, H. Vincent
Space-time block coded spatial modulation (STBC-SM) which employs space-time block coding (STBC) for spatial modulation (SM) is proposed as a new multiple-input multiple-output (MIMO) transmission scheme. In the STBC-SM scheme the transmitted information symbols are expanded not only to the space and time domains but also to the spatial (antenna) domain therefore both core STBC and antenna indices carry information. A general framework is presented for the design of the STBC-SM scheme for any number of transmit antennas. The proposed scheme is optimized by deriving its diversity and coding gains to exploit the diversity advantage of STBC. A low-complexity maximum likelihood (ML) decoder is given for the new scheme. It is shown by computer simulations that STBC-SM provides approximately 3-5 dB (depending on the spectral efficiency) better error performance than SM and V-BLAST systems.
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: 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.