Assisted random access procedure for NR-U
An assisted random-access procedure allows band sharing between New Radio Unlicensed (NR-U) and Wi-Fi to improve coexistence of NR-U and Wi-Fi in shared unlicensed bands (e.g., below 7 GHz). To connect to an NR-U network, NR-U User Equipment (UE) receives and decodes an NR-U preamble of an NR-U wireless transmission to determine NR-U channel occupancy time (COT). The NR-U UE detects Wi-Fi wireless transmissions and decodes a Wi-Fi preamble to determine Wi-Fi COT. A random access (RA) opportunity is acquired based upon the NR-U wireless transmission and the NR-U COT. When the RA opportunity is not during the Wi-Fi COT, a PRACh message is transmitted from the NR-U UE to a NR-U base station (gNB) to allow the NR-U UE to join the NR-U network. NR-U transmissions may include an NR-U common preamble that may be decoded by existing Wi-Fi devices to avoid collisions with NR-U wireless transmissions.
1. An assisted random-access procedure for New Radio Unlicensed (NR-U) to share a band with Wi-Fi, comprising:
receiving, by NR-U User Equipment (UE), an NR-U wireless transmission;
decoding the NR-U wireless transmission to determine an NR-U channel occupancy time (COT);
detecting, by the NR-U UE, a Wi-Fi wireless transmission including a Wi-Fi preamble;
decoding the Wi-Fi preamble to determine a Wi-Fi COT;
acquiring a random access (RA) opportunity based upon the NR-U wireless transmission; and
transmitting, during the RA opportunity, a physical random-access channel (PRACh) message from the NR-U UE to a NR-U base station (gNB) when (a) the RA opportunity does not occur during the NR-U COT or the Wi-Fi COT, or when (b) the NR-U COT is from the gNB and the RA opportunity occurs within a remainder of the NR-U COT, and the RA opportunity does not occur within the Wi-Fi COT;
wherein the step of transmitting further comprises performing listen-before-talk (LBT) when (c) the RA opportunity is not within the NR-U COT and when (d) the RA opportunity is within the NR-U COT but the NR-U COT is not generated by the gNB.
2. The assisted random-access procedure of claim 1 , the LBT comprising performing clear channel assessment (CCA) to determine that a transmission channel is clear of other transmissions prior to transmitting the PRACh message.
3. The assisted random-access procedure of claim 1 , further comprising determining that the NR-U COT is generated by the gNB when a NR-U common preamble of the NR-U wireless transmission indicates a transmission direction of the NR-U wireless transmission is from the gNB.
4. The assisted random-access procedure of claim 1 , further comprising:
determining that the PRACh message is not successful; and
repeating the steps of acquiring, detecting, decoding the Wi-Fi preamble, performing, and transmitting when the PRACh message is not successful.
5. The assisted random-access procedure of claim 1 , the step of acquiring the RA opportunity comprising calculating a time availability (Ta) for transmitting the PRACh message based, at least in part, upon the NR-U wireless transmission.
6. The assisted random-access procedure of claim 1 , further comprising generating a NR-U common preamble having, at least in part, a Wi-Fi preamble format decodable by existing Wi-Fi devices, wherein the NR-U common preamble is included in transmissions from the NR-U UE and transmissions from the gNB.
7. An assisted random-access procedure for New Radio Unlicensed (NR-U) to share a band with Wi-Fi, comprising:
receiving, by NR-U User Equipment (UE), an NR-U wireless transmission;
decoding the NR-U wireless transmission to determine an NR-U channel occupancy time (COT);
detecting, by the NR-U UE, a Wi-Fi wireless transmission including a Wi-Fi preamble;
decoding the Wi-Fi preamble to determine a Wi-Fi COT;
acquiring a random access (RA) opportunity based upon the NR-U wireless transmission; and
transmitting, during the RA opportunity, a PRACh message from the NR-U UE to a NR-U base station (gNB) when (a) the RA opportunity does not occur during the NR-U COT or the Wi-Fi COT, or when (b) the NR-U COT is from the gNB and the RA opportunity occurs within a remainder of the NR-U COT, and the RA opportunity does not occur within the Wi-Fi COT;
wherein the PRACh message is transmitted without listen-before-talk (LBT) when both (c) the RA opportunity occurs during a remainder of the NR-U COT and (d) the NR-U COT is generated by the gNB.
8. The assisted random-access procedure of claim 7 , wherein transmission of the PRACh message does not overlap a downlink part of the NR-U COT.