An Improved Receiver Architecture for Cyclic-Prefixed OFDM

Garbo, G.; Mangione, Stefano

doi:10.1109/wcnc.2009.4917584

Cited by 3 publications

(10 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that this equalizer features a higher latency than the conventional equalizer and some of the works in the literature such as [15], [20] and [29]. However, such a latency is intrinsic to a turbo receiver due to the use of the interleaver/de-interleaver.…”

Section: B Calculations Ofmentioning

confidence: 98%

“…Performance comparison with [15], [20] and [21] In this set of simulations, we apply the methods in [15], [20] and [21] in turbo equalization systems and compare their performance with our proposed reduced-complexity algorithm.…”

Section: B Performance With Channel Estimation Errormentioning

confidence: 99%

“…1) For exploiting the CP in OFDM systems, the equalizers proposed in the literature such as [20] and [21] are at least of O(N 3 ) complexity per data block per iteration, while our proposed reduced-complexity equalizer is only of O(N log 2 N ) per data block per iteration, therefore making it desirable for use in practical applications. 2) Our proposed equalizer utilizes the full CP observation after interference cancellation and the tail of each block in the succeeding block (see the grey triangles in Fig.…”

Section: Introductionmentioning

confidence: 98%

“…For data detection only, the methods in [14]- [23], [29], [30] can be extended to turbo equalization systems to make use of the CP. However, these methods feature a very high complexity, for instance, the minimum mean square error (MMSE) method in [20] is of cubic complexity. In [31], we propose a low-complexity equalization algorithm for the iterative SC-FDE systems.…”

Section: Introductionmentioning

confidence: 99%

“…2) Our proposed equalizer utilizes the full CP observation after interference cancellation and the tail of each block in the succeeding block (see the grey triangles in Fig. 2(b)) as well, while previous equalizers such as [15], [20] and [21] only make use of the CP or part of the CP for detection. As a result, simulation results show that our proposed equalizer achieves 1dB performance gain over the MMSE equalizers in [20] and [21] and 2dB gain over the MMSE equalizer in [15] for the system setup in Section V. 3) An SNR analysis is provided to verify the performance improvement of our proposed equalizer over the conventional equalizer.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A Factor Graph Approach to Exploiting Cyclic Prefix for Equalization in OFDM Systems

Yang

Guo

Huang

et al. 2013

IEEE Trans. Commun.

View full text Add to dashboard Cite

In OFDM systems, cyclic prefix (CP) insertion and removal enables the use of a set of computationally efficient single-tap equalizers at the receiver. Due to the extra transmission time and energy, the CP causes a loss in both spectrum efficiency and power efficiency. On the other hand, as a repetition of part of the data, the CP brings extra information and can be exploited for detection. Therefore, instead of discarding the CP observation as in the conventional OFDM system, we utilize all the received signals in a soft-input soft-output equalizer of a turbo equalization OFDM system. First, the models for both the CP part and the non-CP part of observation are presented in a Forney-style factor graph (FFG). Then based on the computation rules of the FFG and the Gaussian message passing (GMP) technique, we develop an equalization algorithm. With proper approximation, the complexity of the proposed algorithm is reduced to O(2RN log2N + 4RGlog2G + 2RG) per data block for R iterations, where N is the length of the data block and G is equal to P + L − 1 with P the length of the CP and L the maximum delay spread of the channel. To justify the performance improvement, SNR analysis is provided. Simulation results show that the proposed approach achieves a significant gain over the conventional approach and the turbo equalization system converges within two iterations.

show abstract

Section: B Calculations Ofmentioning

confidence: 98%

Section: B Performance With Channel Estimation Errormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Factor Graph Approach to Exploiting Cyclic Prefix for Equalization in OFDM Systems

Yang

Guo

Huang

et al. 2013

IEEE Trans. Commun.

View full text Add to dashboard Cite

show abstract

A Channel-Aware Adaptive Modem for Underwater Acoustic Communications

et al. 2021

Self Cite

View full text Add to dashboard Cite

Acoustic underwater channels are very challenging, because of limited bandwidth, long propagation delays, extended multipath, severe attenuation, rapid time variation and large Doppler shifts. A plethora of underwater communication techniques have been developed for dealing with such a complexity, mostly tailoring specific applications scenarios which can not be considered as one-size-fits-all solutions. Indeed, the design of environment-specific solutions is especially critical for modulations with high spectral efficiency, which are very sensitive to channel characteristics. In this paper, we design and implement a software-defined modem able to dynamically estimate the acoustic channel conditions, tune the parameters of a OFDM modulator as a function of the environment, or switch to a more robust JANUS/FSK modulator in case of harsh propagation conditions. The temporal variability of the channel behavior is summarized in terms of maximum delay spread and Doppler spread. We present a very efficient solution for deriving these parameters and discuss the limit conditions under which the OFDM modulator can work. In such scenarios, we also calibrate the prefix length and the number of sub-carriers for limiting the inter-symbol interference and signal distortions due to the Doppler effect. We validate our estimation and adaptation techniques by using both a custom-made simulator for time-varying underwater channels and the well-known Watermark simulator, as well as real in field experiments. Our results show that, for many practical cases, a dynamic adjustment of the prefix length and number of sub-carriers may enable the utilization of OFDM modulations in underwater communications, while in harsher environments JANUS can be used as a fall-back modulation.

show abstract