Random access preamble receiver
地域：
Stockholm
摘要
Systems and methods for processing a Random Access (RA) transmission are disclosed. In some embodiments, a method of operating a radio access node in a cellular communications network includes receiving an RA transmission from a wireless device. The method also includes detecting an RA preamble in the RA transmission from the wireless device and estimating a timing parameter of the wireless device using the RA transmission from the wireless device separately from detecting the RA preamble. By estimating the timing parameter separately from detecting the RA preamble, increased detection of the RA preamble is possible while also increasing the precision of the timing parameter estimate. In some embodiments, this separation also enables a complexity reduction of the receiver if a low complexity detector is used first and then the high complexity timing estimator is only used when an RA preamble is detected.
說明書
This application is a national stage application of International Patent Application No. PCT/IB2017/052709, filed May 9, 2017, which claims the benefit of provisional patent application Ser. No. 62/336,190, filed May 13, 2016, the disclosures of which are hereby incorporated herein by reference in their entireties.
The disclosed subject matter relates generally to telecommunications and more particularly to receivers and related technologies.
The upcoming standalone Long Term Evolution in Unlicensed Spectrum (LTE-U) forum and future Third Generation Partnership Project (3GPP) Rel-14 work item on uplink Licensed-Assisted Access (LAA) intends to allow LTE User Equipments (UEs) to transmit on the uplink in the unlicensed 5 gigahertz (GHz) or license-shared 3.5 GHz radio spectrum. For the case of standalone LTE-U, the initial Random Access (RA) and subsequent uplink (UL) transmissions take place entirely on the unlicensed spectrum. Regulatory requirements may not permit transmissions in the unlicensed spectrum without prior channel sensing. Because the unlicensed spectrum is generally shared with other radios of similar or dissimilar wireless technologies, a so-called Listen-Before-Talk (LBT) method should be applied. LBT involves sensing the medium for a pre-defined minimum amount of time and backing off if the channel is busy. Therefore, the initial RA procedure for standalone LTE-U should involve as few transmissions as possible and also have low latency, such that the number of LBT operations can be minimized and the RA procedure can then be completed as quickly as possible. There is a need for an improved RA procedure to address these issues.
權(quán)利要求
What is claimed is:1. A method of operating a radio access node in a cellular communications network to process a random access transmission, the method comprising: receiving the random access transmission from a wireless device; detecting a random access preamble in the random access transmission from the wireless device, wherein detecting the random access preamble in the random access transmission from the wireless device comprises detecting the random access preamble using an oversampled Inverse Fast Fourier Transform (IFFT) of the random access transmission from the wireless device; and estimating a timing parameter of the wireless device using the random access transmission from the wireless device separately from detecting the random access preamble. 2. The method of claim 1 wherein estimating the timing parameter of the wireless device comprises:estimating the timing parameter of the wireless device using the random access transmission from the wireless device in response to detecting the random access preamble in the random access transmission from the wireless device. 3. The method of claim 1 wherein using the oversampled IFFT of the random access transmission from the wireless device comprises zero padding of the signal to be processed by the IFFT. 4. The method of claim 1 wherein estimating the timing parameter of the wireless device using the random access transmission from the wireless device comprises estimating the timing parameter using a wideband IFFT of the random access transmission from the wireless device. 5. The method of claim 4 wherein using the wideband IFFT comprises calculating an IFFT of the random access transmission from the wireless device where values that do not contain the random access preamble are zeroes such that the wideband IFFT spans a whole system bandwidth. 6. The method of claim 1 wherein receiving the random access transmission from the wireless device comprises receiving a plurality of interlaced random access intervals where each interval contains the random access preamble. 7. The method of claim 6 wherein each random access interval of the plurality of interlaced random access intervals is one resource block. 8. The method of claim 6 further comprising:extracting the plurality of interlaced random access intervals from the random access transmission from the wireless device; and processing each random access interval of the plurality of interlaced random access intervals with a corresponding matched filter. 9. The method of claim 8 wherein each random access interval of the plurality of interlaced random access intervals includes a cyclic prefix and each of the corresponding matched filters is the same. 10. The method of claim 8 wherein each random access interval of the plurality of interlaced random access intervals does not include a cyclic prefix and at least one of the corresponding matched filters is different. 11. The method of claim 1 wherein the cellular communications network is one of:a Long Term Evolution (LTE) cellular communications network; a Long Term Evolution in Unlicensed Spectrum (LTE-U) cellular communications network; or a New Radio (NR) cellular communications network. 12. The method of claim 1 wherein receiving the random access transmission from the wireless device comprises receiving the random access transmission from the wireless device on a Physical Random Access Channel (PRACH). 13. A radio access node comprising:at least one processor; and memory comprising instructions executable by the at least one processor whereby the radio access node is operable to:receive a random access transmission from a wireless device; detect a random access preamble in the random access transmission from the wireless device, wherein detecting the random access preamble in the random access transmission from the wireless device comprises being operable to detect the random access preamble using a narrowband Inverse Fast Fourier Transform (IFFT) of the random access transmission from the wireless device; and estimate a timing parameter of the wireless device using the random access transmission from the wireless device separately from detecting the random access preamble. 14. The radio access node of claim 13 wherein estimating the timing parameter of the wireless device comprises being operable to:estimate the timing parameter of the wireless device using the random access transmission from the wireless device in response to detecting the random access preamble in the random access transmission from the wireless device. 15. The radio access node of claim 13 wherein using the oversampled IFFT of the random access transmission from the wireless device comprises zero padding of the IFFT. 16. The radio access node of claim 13 wherein estimating the timing parameter of the wireless device using the random access transmission from the wireless device comprises being operable to estimate the timing parameter using a wideband IFFT of the random access transmission from the wireless device. 17. The radio access node of claim 16 wherein using the wideband IFFT comprises being operable to calculate an IFFT of the random access transmission from the wireless device where values that do not contain the random access preamble are zeroes such that the wideband IFFT spans a whole system bandwidth. 18. The radio access node of claim 13 wherein receiving the random access transmission from the wireless device comprises being operable to receive a plurality of interlaced random access intervals where each interval contains the random access preamble. 19. The radio access node of claim 18 wherein each random access interval of the plurality of interlaced random access intervals is one resource block. 20. The radio access node of claim 18 further operable to:extract the plurality of interlaced random access intervals from the random access transmission from the wireless device; and process each random access interval of the plurality of interlaced random access intervals with a corresponding matched filter. 21. The radio access node of claim 20 wherein each random access interval of the plurality of interlaced random access intervals includes a cyclic prefix and each of the corresponding matched filters is the same. 22. The radio access node of claim 20 wherein each random access interval of the plurality of interlaced random access intervals does not include a cyclic prefix and at least one of the corresponding matched filters is different. 23. A tangible, non-transitory computer-readable storage medium, having instructed stored thereon that, when executed by a processing device, cause the processing device to perform operations comprising:receiving a random access transmission from a wireless device; detecting a random access preamble in the random access transmission from the wireless device, wherein detecting the random access preamble in the random access transmission from the wireless device comprises being operable to detect the random access preamble using a narrowband Inverse Fast Fourier Transform (IFFT) of the random access transmission from the wireless device; and estimating a timing parameter of the wireless device using the random access transmission from the wireless device separately from detecting the random access preamble.
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