On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications
The DFT-based demodulator for BFSK has been introduced for applications where the received signal experiences a carrier frequency offset (CFO) much larger than the symbol rate. The Ultra-Narrowband (UNB) communication techniques have been introduced for implementing the emerging Low Power Wide Area...
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| Format: | Article |
| Language: | English |
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IEEE
2020-01-01
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| Series: | IEEE Access |
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| Online Access: | https://ieeexplore.ieee.org/document/9154670/ |
| _version_ | 1818444194254946304 |
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| author | Siavash Safapourhajari Andre B. J. Kokkeler |
| author_facet | Siavash Safapourhajari Andre B. J. Kokkeler |
| author_sort | Siavash Safapourhajari |
| collection | DOAJ |
| description | The DFT-based demodulator for BFSK has been introduced for applications where the received signal experiences a carrier frequency offset (CFO) much larger than the symbol rate. The Ultra-Narrowband (UNB) communication techniques have been introduced for implementing the emerging Low Power Wide Area Networks (LPWAN). Since UNB communication is prone to CFO, a DFT-based BFSK demodulator is an interesting option for this type of communication. However, for proper operation in a large frequency offset, the DFT-based demodulator requires a complex window synchronization which is not desirable for low power nodes. The main source of complexity, is calculating the DFT of a window which slides over the preamble. In this work, the complexity is alleviated by considering the window synchronization algorithm and its implementation together. First, a new window synchronization algorithm is proposed which is designed such that an efficient class of implementations of the sliding DFT (SDFT), called Single Bin SDFT (SB-SDFT) in this work, can be used. Moreover, a new stable implementation of SB-SDFT is designed to enable zero-padding which is required by the demodulator. The complexity of the proposed algorithm implemented using the SB-SDFT, scales more efficiently compared to the conventional algorithm when the range of tolerable CFO increases. Using the proposed method, for a CFO tolerance in the order of 14.5 times the symbol rate (±14.5 kHz for a symbol rate equal to 100 Hz), the number of complex operations is reduced by more than 85% (and memory by 90%) compared to the conventional method. |
| first_indexed | 2024-12-14T19:12:03Z |
| format | Article |
| id | doaj.art-133426ed98464d88a7d6e9d380b9d024 |
| institution | Directory Open Access Journal |
| issn | 2169-3536 |
| language | English |
| last_indexed | 2024-12-14T19:12:03Z |
| publishDate | 2020-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj.art-133426ed98464d88a7d6e9d380b9d0242022-12-21T22:50:41ZengIEEEIEEE Access2169-35362020-01-01814666614668210.1109/ACCESS.2020.30139869154670On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband CommunicationsSiavash Safapourhajari0https://orcid.org/0000-0001-7648-1128Andre B. J. Kokkeler1Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, AE Enschede, The NetherlandsFaculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, AE Enschede, The NetherlandsThe DFT-based demodulator for BFSK has been introduced for applications where the received signal experiences a carrier frequency offset (CFO) much larger than the symbol rate. The Ultra-Narrowband (UNB) communication techniques have been introduced for implementing the emerging Low Power Wide Area Networks (LPWAN). Since UNB communication is prone to CFO, a DFT-based BFSK demodulator is an interesting option for this type of communication. However, for proper operation in a large frequency offset, the DFT-based demodulator requires a complex window synchronization which is not desirable for low power nodes. The main source of complexity, is calculating the DFT of a window which slides over the preamble. In this work, the complexity is alleviated by considering the window synchronization algorithm and its implementation together. First, a new window synchronization algorithm is proposed which is designed such that an efficient class of implementations of the sliding DFT (SDFT), called Single Bin SDFT (SB-SDFT) in this work, can be used. Moreover, a new stable implementation of SB-SDFT is designed to enable zero-padding which is required by the demodulator. The complexity of the proposed algorithm implemented using the SB-SDFT, scales more efficiently compared to the conventional algorithm when the range of tolerable CFO increases. Using the proposed method, for a CFO tolerance in the order of 14.5 times the symbol rate (±14.5 kHz for a symbol rate equal to 100 Hz), the number of complex operations is reduced by more than 85% (and memory by 90%) compared to the conventional method.https://ieeexplore.ieee.org/document/9154670/Frequency shift keying (FSK)frequency offsetsliding DFTultra-narrowband (UNB)offset tolerant demodulator |
| spellingShingle | Siavash Safapourhajari Andre B. J. Kokkeler On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications IEEE Access Frequency shift keying (FSK) frequency offset sliding DFT ultra-narrowband (UNB) offset tolerant demodulator |
| title | On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications |
| title_full | On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications |
| title_fullStr | On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications |
| title_full_unstemmed | On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications |
| title_short | On the Low Complexity Implementation of the DFT-Based BFSK Demodulator for Ultra-Narrowband Communications |
| title_sort | on the low complexity implementation of the dft based bfsk demodulator for ultra narrowband communications |
| topic | Frequency shift keying (FSK) frequency offset sliding DFT ultra-narrowband (UNB) offset tolerant demodulator |
| url | https://ieeexplore.ieee.org/document/9154670/ |
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