Abstract
Channel estimation (CE) is a field of study that has garnered much attention during recent years. CE plays an important role in developing channel equalizers. There are many approaches to CE, among which there are orthogonal codes (OC) and orthogonal space-time block codes (OSTBC). Also, complementary codes (CC) have been under investigation for multiple-input, multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) CE. There are zero side-lobe levels in a CC signal’s autocorrelation function. The initial area of application of these signals has been radar systems, and they were used as optimal phase-coding signals. These signals require the use of two different channels to transmit the twofold components of the pilot code. Thus, this research introduces the two-sided CE (TSCE), where separate subcarrier locations are used to carry the two pilot CCs. Equalization errors can occur in dangerous situations, in case a system is interfered with or jammed. This leads to negative impacts on the accuracy of channel estimation. This situation specifically occurs when a harsh Doppler spread is present, as a result of a deterioration in the orthogonality of the subcarriers of the OFDM. Certain conditions were applied for testing the performance of the method suggested in this paper, i.e., the MIMO-OFDM TSCE approach, the method that depends on CCs. These conditions are the Doppler spread, as well as partial-band jamming. Among the different MIMO-OFDM CE techniques, TSCC-CE has shown good performance, with its ability to withstand the effect of partial-band jamming on the accuracy of the MIMO-OFDM CE. This improved performance takes place in the presence of a Doppler spread of moderate value and a partial-band jamming ratio.
Highlights
Due to its major importance and its constant applications during this era, wireless communication has become a point of focus for researchers
Even though this paper takes a look at the same issue as other research [17], it focuses on a different scenario with different conditions, i.e., the application of Doppler spread and jamming attacks on the channel under-estimation
This paper proposed a new technique for use in channel estimation, based on complementary codes
Summary
Due to its major importance and its constant applications during this era, wireless communication has become a point of focus for researchers. These techniques use received data symbols and a channel’s statistical information to reach CSI [3,4] These techniques can only be used in slowly time-varying channels, a drawback accompanied by another in the form of lower estimation performance, i.e., high complexity operation, resulting from the long duration of data recording. The CE technique proposed in this paper was tested on a 2x2 MIMO-OFDM wireless system, under the following conditions: the presence of both Doppler spread and adversarial jamming. Even though this paper takes a look at the same issue (techniques used in MIMO-OFDM channel estimation) as other research [17], it focuses on a different scenario with different conditions, i.e., the application of Doppler spread and jamming attacks on the channel under-estimation.
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