Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Semi-blind approach of continuous time-tracking for DAB/DAB+

IP.com Disclosure Number: IPCOM000249272D
Publication Date: 2017-Feb-15
Document File: 4 page(s) / 203K

Publishing Venue

The IP.com Prior Art Database

Abstract

For the purpose of time-tracking (adjustments of the FFT window position), the DAB/DAB+ standard only provides a preamble symbol at a repetition rate of up to 96ms. For physical channel conditions, where the length of the channel impulse response exceeds the guard interval (out-of-Guard channels) this slow update rate of the time-tracking is not sufficient. This invention disclosure describes a method of semi-blind continuous time-tracking for DAB/DAB+, which can be carried out every OFDM symbol (update rate for DAB/DAB+ up to 1.246ms). For out-of-Guard channels and in particular in case of high mobility, a continuous time-tracking algorithm maximizes the SINR of the extracted signal, and therefore limits the reception capabilities to either receive or loose the DAB/DAB+ service. The proposed method provides a competitive and differentiating feature. For DAB/DAB+ out-of-Guard channels may occur in particular in SFN networks, where the channel impulse response length is determined by the propagation difference of the transmit signals which are emitted by different SFN towers. Here the propagation difference is measured at the receive antenna. The disclosed method is explained on the example of DAB/DAB+, however, it can also be used for other wireless communication standards, which transmit a perfectly know preamble symbol at a known repetition rate e.g. 802.11 (WiFi), DRM/DRM+, CDR, DVB-T.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 38% of the total text.

Semi-blind approach of continuous time-tracking for DAB/DAB+

Abstract

For the purpose of time-tracking (adjustments of the FFT window position), the DAB/DAB+ standard

only provides a preamble symbol at a repetition rate of up to 96ms. For physical channel conditions,

where the length of the channel impulse response exceeds the guard interval (out-of-Guard

channels) this slow update rate of the time-tracking is not sufficient.

This invention disclosure describes a method of semi-blind continuous time-tracking for DAB/DAB+,

which can be carried out every OFDM symbol (update rate for DAB/DAB+ up to 1.246ms).

For out-of-Guard channels and in particular in case of high mobility, a continuous time-tracking

algorithm maximizes the SINR of the extracted signal, and therefore limits the reception capabilities

to either receive or loose the DAB/DAB+ service. The proposed method provides a competitive and

differentiating feature.

For DAB/DAB+ out-of-Guard channels may occur in particular in SFN networks, where the channel

impulse response length is determined by the propagation difference of the transmit signals which

are emitted by different SFN towers. Here the propagation difference is measured at the receive

antenna.

The disclosed method is explained on the example of DAB/DAB+, however, it can also be used for

other wireless communication standards, which transmit a perfectly know preamble symbol at a

known repetition rate e.g. 802.11 (WiFi), DRM/DRM+, CDR, DVB-T.

Related Art

Problem

In OFDM based SFN networks, the same transmit signal is broadcasted simultaneously by various

emitting towers on the same carrier frequency. The received signal at the receiver is always the

superposition of all transmitted signals. Therefore the channel impulse response contains all received

signal paths, which are individually attenuated due to path loss and delayed due to their physical signal

propagation.

Those SFN signals which arrive at the receiver within the timespan of the guard interval (in-guard

channels) contribute to the wanted signal energy. However, those signal parts which arrive outside of

the guard interval contribute to inter-symbol-interference, and thus disturb the wanted signal

reception.

In a mobile environment the attenuation of the received SFN signal contributions are continuously

changing and fading. Therefore the Time-Tracking algorithm at the receiver side is in charge to adjust

the timing position for the FFT window extraction such that the SINR (Signal to Noise+Interference

Ratio) is maximized. For Out-of Guard channels, this means that the Time-Tracking algorithm needs to

monitor all relevant signal contributions over time, and move the FFT window position accordingly.

For DAB/DAB+ the Time-Tracking algorithm is carried out on a perfectly known preamble symbol (TFPR

symbol). A cross-correlation of the received signal with the perfectly known preamble provides the

estimated channel impulse response at the receive antenna. Depending on the...