CN-115918239-B - Detection of directional channel access

Abstract

Methods of using unlicensed transmission spectrum in a cellular communication network are provided. The UE is allowed to transmit for a short period of time, such as a Random Access Channel (RACH) transmission, without performing a procedure that listens before transmission. The base station performs a procedure of directional listening before transmission and schedules UE transmissions on the available transmission spectrum. The UE may perform a procedure of listening before transmission, and may determine whether to allow the UE to transmit using a power difference between interlaces.

Inventors

• Bruno jejux
• Virgil Garcia

Assignees

• TCL通讯（宁波）有限公司

Dates

Publication Date

20260512

Application Date

20210617

Priority Date

20200617

Claims (11)

1. 1. A method of performing a channel access procedure, the method being performed by a user equipment, UE, using unlicensed transmission spectrum, the method comprising the steps of: A detection operation is performed that listens before transmission, wherein power on multiple interlaces is detected, The total received power is compared to a first threshold, and if the detected total power is below the threshold, transmission is allowed, otherwise, If the detected total power is above the threshold, a difference in the detected power between the highest and lowest power interlaces is calculated and if the difference is above a second threshold, transmission is allowed, otherwise if the difference is below the second threshold, transmission is not allowed.
2. 2. The method of claim 1, wherein the pre-transmission listening detection operation is an omni-directional operation.
3. 3. The method of claim 1, wherein the pre-transmission snoop detection operation is a directional operation.
4. 4. The method according to any of the preceding claims, wherein the UE applies an offset to the first threshold.
5. 5. The method of claim 4, wherein the offset is selected to compensate for a beamforming imbalance between the UE and an associated base station.
6. 6. The method of claim 4, wherein the offset is received from a base station.
7. 7. The method of claim 4, wherein the offset is semi-static or dynamic.
8. 8. The method according to claim 6, characterized in that the offset is received in radio resource control, RRC, signaling or in a downlink control information, DCI, message.
9. 9. The method of claim 4, wherein the offset is UE-specific.
10. 10. The method of claim 4, wherein the offset is cell-specific.
11. 11. A user equipment, UE, characterized in that the UE comprises means for performing the method of any of claims 1 to 10.

Description

Detection of directional channel access Technical Field The present disclosure relates to channel access detection, in particular, such detection is performed prior to directional transmission. Background Wireless communication systems, such as third generation (3G) mobile phone standards and technologies, are well known, and the third generation partnership project (3 GPP) has developed such 3G standards and technologies, and generally, third generation wireless communications have been developed to the extent that macrocell mobile phone communications are supported, communication systems and networks have been developed toward broadband and mobile systems. In a cellular wireless communication system, a User Equipment (UE) is connected to a radio access network (Radio Access Network, RAN) via a wireless link. The RAN includes a set of base stations (base stations) providing radio links to UEs located in cells covered by the base stations and includes an interface to a Core Network (CN) having a function of controlling the overall Network. It is understood that the RAN and CN each perform a corresponding function with respect to the entire network. For convenience, the term "cellular network" will be used to represent a combination of RAN and CN, but it will be understood that the term is also used to represent various systems for performing the disclosed functions. The third generation partnership project has evolved a so-called Long Term Evolution (LTE) system, an evolved universal mobile telecommunications system regional radio access network (E-UTRAN), for a mobile access network of one or more macro cells supported by base stations called enodebs or enbs (evolved nodebs). Recently, LTE has evolved further to so-called 5G or New Radio (NR) systems, where one or more cells are supported by a base station called a gNB. When NR is proposed, an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexed, OFDM) physical transport format is utilized. The NR protocol is intended to provide the option of operating in the unlicensed radio frequency range (referred to as NR-U). While operating in the unlicensed radio band, the gNB and UE must compete for physical medium/resource access with other devices. For example, wi-Fi, NR-U, and LAA may use the same physical resources. Unlicensed spectrum operation in 3GPP designs employs Listen-before-talk (LBT) as a type of channel access procedure, thus requiring the radio transmitter to apply a clear channel assessment (CLEAR CHANNEL ASSESSMENT, CCA) check before transmission takes place. CCA involves at least Energy Detection (ED) against a certain threshold (ED threshold) for a duration of time to determine whether the channel is occupied or idle. If the channel is occupied, a random back-off (back-off) is applied within the contention window so that the duration of channel idle before the transmitter can transmit is minimized. This also creates randomness between competing devices, thereby avoiding collisions. To protect the transmission of Wi-Fi acknowledgement information (ACK), a delay period (e.g., 43 microseconds to try to pull high traffic) is applied after each occupied CCA slot before back-off again. After the transmitter has obtained the right to access the channel, the transmitter is allowed to transmit for only a limited period of time, referred to as the maximum channel occupancy time (maximum channel occupancy time, MCOT). In order to provide differentiation of channel access priority according to the type of traffic served (e.g. VoIP, video, transmission as far as it is possible or background transmission), four LBT priority classes are defined, with different contention window sizes (contention window size, CWS) and MCOT, as described in section 4.1.2 in TS 37.213. The parameter m p is used to calculate the delay period when the channel is found to be occupied, the delay period for the lower priority class being longer. For the 6GHz unlicensed spectrum, the standards-setting organization has defined a single detection slot or CCA slot as 9 microsecond duration, and for the 60GHz unlicensed spectrum as 5 microsecond duration. Furthermore, the duration of the energy detection is set within a detection time slot. The base station (eNB/gNB) performs a type 1 downlink channel access procedure in which the period spanned by the detection slots detected as idle before the downlink transmission is made is random. Furthermore, each time a channel is found to be occupied, the base station will fall back with a delay period corresponding to the channel access priority used. The type 1 procedure is basically used for initial channel access for most data transmission. The base station (eNB/gNB) performs a type 2 downlink channel access procedure in which the period spanned by the detection slots detected as idle before the downlink transmission is made is deterministic. This is mainly used for data transmission when the same base station o