On channel estimation for 802.11p in highly time-varying vehicular channels

Nagalapur, Keerthi Kumar; Brännström, Fredrik; Ström, Erik G.

doi:10.1109/icc.2014.6884223

Cited by 9 publications

(7 citation statements)

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“…10 shows the FER results obtained using computer simulations for an MF with N FB = 147 byte using the EXP channel with v = 100 km/h and M ′ P = 16. The block based LMMSE channel estimation method (BMMSE) described in our previous work [17] provides FER performance very close to the case with perfect CSI for an SF with same N FB . The LT Hold channel estimation scheme that estimates the channel at the beginning of the frame using the LT OFDM symbols and uses it for the rest of the frame performs poorly due to the highly time-and frequency-varying nature of the channel.…”

Section: Frame Error Rate Measurementsmentioning

confidence: 84%

“…5. The procedure is a modified version of the one described in our previous work [17]. The modification is related to the ability to insert a PT symbol at the end of short frames.…”

Section: Modified Framementioning

confidence: 99%

“…In our previous work [17], we proposed a cross-layered approach to periodically insert complementary pilot OFDM symbols into the 802.11p frame. In contrast to other works that introduce pilots by modifying the transmitter PHY layer, we propose a method to insert pilots by manipulating the transmitted data above the medium access control (MAC) layer.…”

Section: Introductionmentioning

confidence: 99%

“…The modified receiver is implemented by extending an existing HIRATE standard compliant 802.11p transceiver implementation. The main contributions of the paper are: (i) we present an improved version of the algorithm proposed in our previous work [17] to insert complementary training data before the PHY and MAC layers into an 802.11p frame; (ii) linear interpolation which can be easily implemented in hardware is used to utilize the inserted training data for channel estimation; (iii) a modified receiver that utilizes the complementary pilots has been implemented in an FPGA platform; (iv) experiments have been performed to validate the compatibility of the proposed scheme with the standard 802.11 transceivers and to measure the performance of the channel estimation based on linear interpolation. The paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

“…A blockwise linear minimum mean squared error (LMMSE) interpolator that utilizes PT symbols is described in our previous work [17]. The blockwise LMMSE interpolator achieves FER performance close to the case with perfect CSI for suitably chosen M ′ P .…”

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confidence: 99%

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An 802.11p Cross-Layered Pilot Scheme for Time- and Frequency-Varying Channels and Its Hardware Implementation

Nagalapur

Brännström

Ström

et al. 2016

IEEE Trans. Veh. Technol.

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IEEE Transactions on Vehicular Technology (ISSN: 0018-9545)Citation for the published paper: Nagalapur, K. ; Brännström, F. ; Ström, E. et al. (2016) "An 802.11p Cross-Layered Pilot Scheme for Time-and Frequency-Varying Channels and Its Hardware Implementation".Abstract-Robust channel estimation in IEEE 802.11p systems in highly time-and frequency-varying vehicular channels in combination with long data packets is a challenging task due to the ill-suited pilot pattern. Solutions of increased receiver complexity that use decision feedback and iterative decoding have been proposed to overcome the difficulty in robust channel estimation. In this work, a cross-layered method to introduce complementary training symbols into an 802.11p frame is proposed. In the proposed approach, known bits are multiplexed with the data in higher layers and a modified receiver can utilize these bits as training data for improved channel estimation. A standard receiver treats these bits as data and passes them to the higher layers where they can be removed, making the method compatible with the standard 802.11p transceivers. A software/firmware update of the higher layers is needed in a standard receiver to remove the multiplexed bits. A modified receiver with low complexity channel estimation schemes that utilizes the complementary training symbols is implemented in a field programmable gate array platform. Frame error rate measurements have been performed by interfacing the hardware implementation with a channel emulator. The measurement results follow the computer simulation results validating the hardware implementation. Moreover, measurement results show that the modified receiver follows the performance of an ideal receiver that has full knowledge of the channel (with only an offset in signal-to-noise ratio) and significantly outperforms the commercial 802.11p transceiver we tested.

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Section: Frame Error Rate Measurementsmentioning

confidence: 84%

“…5. The procedure is a modified version of the one described in our previous work [17]. The modification is related to the ability to insert a PT symbol at the end of short frames.…”

Section: Modified Framementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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