Power Spectrum Characterization of Systematic Coded UW-OFDM Systems

Rajabzadeh, Morteza; Steendam, Heidi; Khoshbin, Hossein

doi:10.1109/vtcfall.2013.6692372

Cited by 12 publications

(10 citation statements)

References 17 publications

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“…for Case 2 4 . When the received energy is normalized (this corresponds to the maximization of the minimum Euclidean distance at the receiver), all eigenvalues are equal, so that the BER reduces to Q η(h)…”

Section: A Deterministic Channelmentioning

confidence: 99%

“…Hence, to compute the coding gain, the determinant of the matrix B H e B e has to be minimized over the error vector e. To optimize the error rate performance, we will use the degrees of freedom available in the selection of the generator matrix G through the decomposition (4). In order to find the minimum (over the error vector e) of det(B H e B e ), we rewrite the elements a m (20):…”

Section: B Channel Unknownmentioning

confidence: 99%

“…Moreover, the addition of the redundancy has no adverse effect on the data throughput: both UW-OFDM and CP-OFDM have essentially the same throughput efficiency. Furthermore, in [4], it is shown that the out-of-band radiation is considerably lower in UW-OFDM than in CP-OFDM, and by sacrificing a few carriers [5], this outof-band radiation can be made essentially zero. Consequently, UW-OFDM is highly spectrally efficient and is therefore a viable solution for e.g.…”

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confidence: 99%

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Theoretical Performance Evaluation and Optimization of UW-OFDM

Steendam

2016

IEEE Trans. Commun.

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Abstract-Unique-word (UW) OFDM is a new OFDM variant that offers several advantages over cyclic prefix OFDM, such as better bit-error-rate (BER) performance in frequency selective channels and much lower out-of-band radiation. However, all results with respect to the BER performance are based on MonteCarlo simulations only, and offer little insight in the behaviour of the system performance as function of its parameters. In this paper, we theoretically analyse the performance of the UW-OFDM system for both a deterministic channel and a fading channel, and offer a systematic way to generate the UW-OFDM signal to optimize the performance of the system. When the fading channel is known at the transmitter, we show that we can obtain a diversity order that is of the same order of magnitude as the theoretically maximum diversity order, but when the channel is not known at the transmitter, it will be very hard to achieve maximum diversity order, although the obtained diversity order is larger than one.

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Section: A Deterministic Channelmentioning

confidence: 99%

Section: B Channel Unknownmentioning

confidence: 99%

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Theoretical Performance Evaluation and Optimization of UW-OFDM

Steendam

2016

IEEE Trans. Commun.

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“…This is confirmed in [2] where a theoretical analysis of the error rate performance shows that UW-OFDM is always able to achieve full diversity, whereas in CP-OFDM only a diversity one is obtained unless precoding is used. Further, it is shown in [3] that UW-OFDM has…”

Section: Uw-ofdmmentioning

confidence: 99%

Design and analysis of the UW-OFDM signal

Steendam

2014

2014 6th International Symposium on Communications, Control and Signal Processing (ISCCSP)

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Unique word (UW-) OFDM is a novel multicarrier system that is shown to be suitable for cognitive radio systems. To construct the UW-OFDM signal, a code generation matrix is required to introduce redundancy in the frequency domain, implying that the code generation matrix must satisfy a number of conditions. In this paper, we use an algebraic construction method to separate the conditions imposed by the signal shape from the code design. The degrees of freedom resulting from this construction method are used to optimize different performance measures (i.e., the minimum Euclidean distance and the power) at the transmitter or at the receiver side. Based on the algebraic decomposition, a composite channel can be defined. Irrespective of whether the optimization is done at the transmitter or the receiver, we shown in the paper that always the strongest modes of this composite channel must be excited.Index Terms-multicarrier communication, error rate, Euclidean distance, tight frame UW-OFDMIn multicarrier communication systems, typically a guard interval is used to combat the effect of intersymbol interference. In traditional multicarrier systems, this guard interval is added on top of the signal containing the data, resulting in a signal with extended symbol duration. Unlike these standard multicarrier systems, unique word (UW-) OFDM counteracts intersymbol interference without the necessity to extend the DFT block with a guard interval. In UW-OFDM, this guard interval is part of the DFT interval, i.e., the last N u samples of the DFT interval are reserved for the unique word, which is a sequence of known samples. In [1], it is shown that UW-OFDM outperforms cyclic prefix (CP-) OFDM with respect to the bit error rate in fading channels. This is confirmed in [2] where a theoretical analysis of the error rate performance shows that UW-OFDM is always able to achieve full diversity, whereas in CP-OFDM only a diversity one is obtained unless precoding is used. Further, it is shown in [3] that UW-OFDM hasThe author gratefully acknowledges the financial support from the Flemish Fund for Scientific Research (FWO). This research has been funded by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office. much lower out-of-band radiation compared to CP-OFDM. Hence, UW-OFDM is an excellent candidate for cognitive radio systems.To construct the UW-OFDM signal, we use the two-step approach. First, we generate the time-domain sequence corresponding to the data symbols, resulting in a block of N u zeroes at the end of the DFT interval. In this block of zeroes, we add the unique word symbols during the second step. The construction of the data contribution containing a block of zeroes in the time domain requires the presence of redundancy in the frequency domain. Consequently, assuming the DFT size equals N , a maximum of N − N u data symbols can be transmitted per DFT block.The UW-OFDM signal is generated as follows. First, the N d ≤ N − N u data symbols a d are fed to the N m × N d code...

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“…The introduction of the unique word within the discrete Fourier transform (DFT) interval requires the introduction of redundancy in the frequency domain. This redundancy can advantageously be utilized to provide several beneficial properties, such as superior spectral shaping characteristics [2], [3], [4], [5], [6] or outstanding bit error ratio (BER) performance for linear [7], [8], [2], [9], [10], [11], non-linear [12], [13], [14] as well as iterative [15], [16] receivers 1 .…”

Section: Introductionmentioning

confidence: 99%

On the Inclusion and Utilization of Pilot Tones in Unique Word OFDM

Hofbauer,

Haselmayr,

Bernhard

et al. 2020

Preprint

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Unique word-orthogonal frequency division multiplexing (UW-OFDM) is known to provide various performance benefits over conventional OFDM using cyclic prefixes (CP). Most important, UW-OFDM features excellent spectral sidelobe suppression properties and an outstanding bit error ratio performance. Current research has mainly focused on principle performance bounds of UW-OFDM, with less attention on challenges aside from idealized communication scenarios, such as system parameter estimation tasks. In this work we present an approach for including frequency pilots tones into the UW-OFDM signaling scheme, which can then be utilized for these estimation tasks. Suitable optimization criteria are presented and interactions of pilots with data symbols are highlighted. Pilot tone based estimation of a carrier frequency offset (CFO) is conducted as an estimation example, revealing considerable differences to conventional OFDM. Simulation results in a multipath environment demonstrate a significantly increased estimation accuracy in UW-OFDM over CP-OFDM, which becomes even more dominant with an increasing CFO. This performance difference is due to the inherent redundancy present in an UW-OFDM signal.

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Power Spectrum Characterization of Systematic Coded UW-OFDM Systems

Cited by 12 publications

References 17 publications

Theoretical Performance Evaluation and Optimization of UW-OFDM

Theoretical Performance Evaluation and Optimization of UW-OFDM

Design and analysis of the UW-OFDM signal

On the Inclusion and Utilization of Pilot Tones in Unique Word OFDM

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