Patent Description:
An example of a cellular communication system is an architecture that is being standardized by the <NUM>rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's LTE upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments. A global bandwidth shortage facing wireless carriers has motivated the consideration of the underutilized millimeter wave (mmWave) frequency spectrum for future broadband cellular communication networks, for example. mmWave (or extremely high frequency) may, for example, include the frequency range between <NUM> and <NUM> gigahertz (GHz). Radio waves in this band may, for example, have wavelengths from ten to one millimeters, giving it the name millimeter band or millimeter wave. The amount of wireless data will likely significantly increase in the coming years. Various techniques have been used in attempt to address this challenge including obtaining more spectrum, having smaller cell sizes, and using improved technologies enabling more bits/s/Hz. One element that may be used to obtain more spectrum is to move to higher frequencies, e.g., above <NUM>. For fifth generation wireless systems (<NUM>), an access architecture for deployment of cellular radio equipment employing mmWave radio spectrum has been proposed. Other example spectrums may also be used, such as cmWave radio spectrum (e.g., <NUM>-<NUM>). Another example can be found in patent documents <CIT> and <CIT>.

According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.

<FIG> is a block diagram of a wireless network <NUM> according to an example implementation. In the wireless network <NUM> of <FIG>, user devices <NUM>, <NUM>, <NUM> and <NUM>, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) <NUM>, which may also be referred to as an access point (AP), an enhanced Node B (eNB), a gNB (which may be a <NUM> base station) or a network node. At least part of the functionalities of an access point (AP), base station (BS) or (e)Node B (eNB) may be also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) <NUM> provides wireless coverage within a cell <NUM>, including to user devices <NUM>, <NUM>, <NUM> and <NUM>. Although only four user devices are shown as being connected or attached to BS <NUM>, any number of user devices may be provided. BS <NUM> is also connected to a core network <NUM> via an interface <NUM>. This is merely one simple example of a wireless network, and others may be used.

A user device (user terminal, user equipment (UE)) may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, and a multimedia device, as examples.

The various example implementations may be applied to a wide variety of wireless technologies, wireless networks, such as LTE, LTE-A, <NUM> (New Radio, or NR), cmWave, and/or mmWave band networks, or any other wireless network or use case. LTE, <NUM>, cmWave and mmWave band networks are provided only as illustrative examples, and the various example implementations may be applied to any wireless technology/wireless network. The various example implementations may also be applied to a variety of different applications, services or use cases, such as, for example, ultra-reliability low latency communications (URLLC), Internet of Things (IoT), enhanced mobile broadband, massive machine type communications (MMTC), vehicle-to-vehicle (V2V), vehicle-to-device, etc. Each of these use cases, or types of UEs, may have its own set of requirements.

A random access procedure (e.g., RACH) is used by user equipment (UE) in an idle or inactive or connected states to access a network, for example to request a setup of a connection. Implementing a RACH includes a four-step procedure ("four-step RACH"). <NUM>) Step <NUM> (Msg1) includes a transmission of a preamble, i.e., a physical RACH (PRACH), from the UE to a base station (gNB). <NUM>) Step <NUM> (Msg2) includes a transmission of a random access response (RAR) from the gNB to the UE. <NUM>) Step <NUM> (Msg3) includes a scheduled transmission of data from the UE to the gNB. <NUM>) Step <NUM> (Msg4) includes a transmission of a contention resolution from the gNB to the UE.

Some UEs implement a RACH procedure that takes emission factors into account in the form of a Maximum Permittable Exposure (MPE). In frequency range <NUM> (FR2), the MPE requirement is highly directional because of "beam" based operation at the UE. The UE is equipped typically with multiple antenna panels each having multiple antenna elements for generating beams for transmission and reception. NB frequency range <NUM> (FR1) is determined in TS38. <NUM> as frequency range from <NUM> to <NUM>. Correspondingly, in TS38. <NUM>, frequency range <NUM> (FR2) is determined as a frequency range from <NUM> to <NUM>.

To ensure compliance with applicable electromagnetic energy absorption requirements and addressing unwanted emissions RAN4 (Radio performance and protocol aspects (system) - RF parameters and BS conformance working group) has agreed so far two approaches. The first approach involves using allowed maximum output power reduction (P-MPR) and the second approach involves using uplink duty cycle. However, use of both approaches impact uplink performance negatively. To address this, the UE capability maxUplinkDutyCycle was approved where the capability allows the UE to signal its preferred maximum UL duty cycle to the network.

NR supports receive beamforming for PRACH preamble reception by allocating multiple RACH occasions (ROs) for which the gNB may use different receive beams. PRACH occasion and PRACH preamble selection by the UE also signals the preferred SS/PBCH (physical broadcast channel) block beam that will be used for Msg2 and Msg4 transmissions.

The allocation is done by configuring an association between an SS/PBCH block and one or more RACH occasion(s) and set of PRACH preambles within each associated occasion. Based on the DL measurements on SS/PBCH block(s), in a conventional RACH procedure, the UE determines the RACH occasions and PRACH preambles within the occasions associated to the selected SS/PBCH block from which the UE selects the preamble for the transmission. Current specification allows UE, in CBRA (contention-based random access) to select RACH Occasions corresponding to any SSB which RSRP (reference signal received power) exceeds the configured threshold (e.g., rsrp-ThresholdSSB). Correspondingly, in case of CFRA (contention-free random access), UE can select any SSB (or CSI-RS) from the configured candidate list (candidateBeamRSList) that exceeds the configured threshold.

Nevertheless, for example in FR2 the UE is typically assumed to be equipped with multiple antenna panels, and the UE operates both in downlink and uplink using beams that are narrower than omni-direction beams typically assumed to be used in FR1 per antenna. When operating with the beams in uplink, a common output power reduction and/or duty cycle is not feasible to be applied because different beams have different conditions what comes to the RF exposure issue: some beams may propagate towards a human body while some other beams not. The former would require higher output power reduction and/or lower duty cycle than the latter.

It is noted that, in some implementations, amount of output power reduction is determined based on the maximum output power that can be used for UL transmission within a certain time, ensuring compliance with applicable electromagnetic energy absorption requirements. In some implementations, the amount of output power reduction is determined autonomously by the UE <NUM> assuming that the UE <NUM> is transmitting continuously on UL resources, a certain portion of UL resources from certain antennae, antenna panels, or beams.

It is noted that, in some implementations, the duty cycle, i.e., the UL duty cycle is determined as the highest portion of UL symbols than can used for UL transmission within a certain time and ensure compliance with applicable electromagnetic energy absorption requirements. In some implementations, the UL duty cycle is determined autonomously by the UE <NUM> assuming that the UE <NUM> would be transmitting at its maximum output power, within a certain range from the maximum output power from certain antennae, antenna panels, or beams.

Correspondingly in the above-described conventional RACH procedure, selecting RO based on the DL measurements (e.g., based on SS/PBCH block or CSI-RS), may not give the desired outcome from the perspective of MPE targets if done solely based on the DL RS RSRP. This may lead to undesirably large output power reduction or small duty cycle, hindering the data activity or coverage.

In contrast to the above-described conventional RACH procedure, an improved technique includes accounting for the difference in required output power reduction or required duty cycle when selecting the RO in addition to the DL RS. Both output power reduction and duty cycle are independently determined by UE itself (i.e., UE needs to be able to determine itself required power backoff and/or duty cycle in order to meet RF exposure requirements). Advantageously, a RACH procedure in which the UE determines both output power reduction and duty cycle independently enables better choices of output power reduction and duty cycle, enhancing data activity and coverage.

<FIG> is a diagram illustrating a multi-beam environment <NUM>. In the environment <NUM>, a UE <NUM> receives UL resource information from a gNB at transmission points <NUM> and <NUM>, each of which produce DL RSs <NUM> and <NUM>, respectively. In the convention RACH approach, the UE <NUM> performs a measurement of the DL RSRP for each of the DL RSs <NUM> and <NUM> and selects UL resources based on the measurement. In contrast, the UE <NUM> determines restrictions on UE resources (e.g., signal power) for each of the plurality of UL resources that might affect the selection of the UL resource over which the UE <NUM> transmits data. The UL has a plurality of antennae, each of which corresponds to one of the DL RSs <NUM> and <NUM> and the UL beams <NUM>.

As shown in <FIG>, there are several UL beams <NUM>, each having a different direction. Some of the UL beams <NUM> are directed away from the user <NUM> and some UL beams <NUM> are directed toward the user <NUM>. In this case, the UL beams <NUM> directed away from the user <NUM> should be able to use a larger power in transmission than those directed toward the user <NUM>.

As shown in <FIG>, the UL resources are associated with an UL beam <NUM>. For example, in some implementations, each beam <NUM> is associated with a physical uplink shared channel (PUSCH) resource and a preamble. In some implementations, the UE <NUM> determines a output power reductionvia a power determination operation. In such a power determination operation, in some implementations, the UE <NUM> generates a respective output power reduction for each of the DL RSs <NUM> and <NUM>. In some implementations, the output power reduction associated with a DL RS is determined based on how much of that DL RS passes through or is absorbed by the user <NUM>. In such implementations, the UE <NUM> uses sensors to determine the proximity of the UE <NUM> to a head or other part of the user <NUM>. Once the output power reduction for each DL RS is determined, the UE <NUM> then adjusts the respective RSRP associated with each DL RS to form a respective adjusted RSRP associated with that RSRP. In some implementations, adjusting includes subtracting the applied output power reduction from the RSRP.

The UE <NUM> then selects a DL RS which adjusted RSRP is above a threshold power. In some implementations, the threshold power is defined in a specification. In some implementations, the threshold power is defined by the network. In some implementations, the network sends a specification of the threshold power with the UL resource information via the gNB.

In some implementations, the UE <NUM> determines a minimum duty cycle for each of the DL RSs. In some implementations, this minimum duty cycle is found independently of the output power reduction, although that duty cycle is found based on MPE requirements concerning exposure to radiation. Because the beams interact differently with the user with regard to the MPE requirements concerning exposure to radiation, it is unlikely that a common output power reduction and duty cycle across the DL RSs is achievable. In some implementations, the UE <NUM> selects a DL RS based on the largest duty cycle greater than the minimum duty cycle.

In some implementations, when no adjusted RSRP is greater than the threshold power, the UE selects a RS associated with the largest duty cycle.

The UE <NUM> maps the DL RS, the output power reduction, and the duty cycle to a RACH occasion (RO). In some implementations, the UE <NUM> ranks the ROs corresponding to a DL RS that exceeds the power threshold based on a required duty cycle so that the RO corresponding to the DL RS with the highest duty cycle is prioritized. In some implementations, this RSRP power threshold evaluation may also be based on a required output power reduction.

In some implementations, only those ROs for which the required duty cycle is greater than a defined duty cycle threshold may be considered or prioritized in a RACH RO selection. In some implementations, if the duty cycle threshold cannot be met without MPR for any DL RS, then the UE <NUM> may select a DL RS with the lowest MPR.

In some implementations, a network may indicate (e.g., in system information together with RACH resource provisioning or using dedicated signalling) a selection of how the UE <NUM> should prioritize the RO selection. That is, the network may indicate the DL RS for which the smallest output power reduction can be met (regardless of the duty cycle), i.e., to prioritize coverage, or for which largest duty cycle can be used (e.g., <NUM>%) regardless the required output power reduction i.e., to prioritize scheduling flexibility.

In some implementations, different ROs or UL resources may be configured for different allowed/tolerated output power reduction or duty cycle levels. This may enable the network to be aware of and account for MPE-related limitations correctly from the start. In some implementations, for certain UL resources, a maximum output power reduction threshold or minimum duty cycle limit is defined.

In some implementations, the above-described RACH procedure is triggered due to the UE <NUM> reaching the maximum output power reduction threshold for at least one, for a subset, or for all UL beams.

In some implementations, the above-described RACH procedure is triggered due to the UE <NUM> reaching the minimum duty cycle limit. That is, for example, the duty cycle due to MPE requirements falls below the limit, where the limit may be <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%.

In some implementations, when the maximum MPR threshold/duty cycle minimum is reached, the UE <NUM> may trigger beam failure recovery on CFRA beams where UE excludes the CFRA candidates with duty cycle below limit value. In some implementations, reaching any of these limits indicates a duty cycle value or a duty cycle limit associated with the selected SSB/CSI-RS in the RACH procedure.

In some implementations, if the UE has a valid C-RNTI, then the UE <NUM> includes the C-RNTI in Msg3 of the (<NUM>-step) RACH procedure.

In some implementations, for output power reduction the UE <NUM> reduces transmission power by 2dB to meet the MPE limits. In some implementations, for duty cycle the UE <NUM> restricts its transmission to <NUM>% of time over <NUM> time period to meet the MPE limits.

It is noted that, for lower frequency bands (e.g., <<NUM>), the MPE limits may be set by a specific absorption rate (SAR), which determines RF power absorbed by certain mass (of living body like material) (units of W/kg). For above <NUM>, the MPE limits are directed to the maximum incident power density (W/m^<NUM>) measured/averaged over certain area (e.g., <NUM>^<NUM>).

Based on the used antenna or antennae array gain, the maximum allowed transmission power to meet the MPE limit is also determined by a given distance. In some implementations, distance is determined by the aforementioned requirements and an antenna/antennae array gain from a given device implementation.

Hence the above-noted requirements can be used to determine the allowed maximum transmission power to meet the emission limits e.g., when certain objects are within a certain distance. This then can be used to determine the power back-off (P-MPR, MPR) as a separation of actual maximum transmission power capability of the UE and the maximum allowed transmission power to meet the MPE limits. Alternatively, when the emission is determined over a certain time period, one can determine a required time domain restriction of the transmission power to meet the MPE limits.

<FIG> is a flow chart illustrating a UE operation <NUM> based on network-provided MPE-related parameters in an example implementation.

At <NUM>, the network sends a signal containing data representing MPE parameters, including the duty cycle threshold and the MPR threshold.

At <NUM>, the UE determines at least one of the MPE parameters does not satisfy the threshold criteria, e.g., that the MPR is greater than the threshold or the duty cycle is less than the threshold.

At <NUM>, the UE selects at least one RO that satisfies the MPE threshold criteria, e.g., that the emissions exposure is smaller than the MPE.

At <NUM>, the UE triggers the RACH procedure on the selected RO.

At <NUM>, in some implementations, the UE indicates the trigger during or after the RACH procedure.

<FIG> is a flow chart illustrating a UE operation <NUM> based on preconfigured MPE-related parameters in an example implementation.

At <NUM>, the UE determines the threshold values for the MPE parameters, including the duty cycle threshold and the MPR threshold.

<FIG> is a flow chart illustrating an example method <NUM> of performing the improved techniques. Operation <NUM> includes receiving, by a user equipment (UE), uplink (UL) resource information from a network describing a plurality of UL resources. Operation <NUM> includes determining, by the UE after receiving the UL resource information and for at least one of the plurality of UL resources, restrictions on the UE resources associated with that UL resource. Operation <NUM> includes selecting, by the UE, at least one of the plurality of UL resources based on the restrictions on the UE resources associated with the at least one of the plurality of UL resources. Operation <NUM> includes transmitting, by the UE, data using the at least one of the plurality of selected UL resources.

<FIG> is a block diagram of a wireless station (e.g., AP, BS, eNB, UE or user device) <NUM> according to an example implementation. The wireless station <NUM> may include, for example, one or two RF (radio frequency) or wireless transceivers 602A, 602B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) <NUM> to execute instructions or software and control transmission and receptions of signals, and a memory <NUM> to store data and/or instructions.

Processor <NUM> may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor <NUM>, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver <NUM> (602A or 602B). Processor <NUM> may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver <NUM>, for example). Processor <NUM> may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor <NUM> may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor <NUM> and transceiver <NUM> together may be considered as a wireless transmitter/receiver system, for example.

In addition, referring to <FIG>, a controller (or processor) <NUM> may execute software and instructions, and may provide overall control for the station <NUM>, and may provide control for other systems not shown in FIG. <NUM>, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station <NUM>, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software.

According to another example implementation, RF or wireless transceiver(s) 602A/602B may receive signals or data and/or transmit or send signals or data. Processor <NUM> (and possibly transceivers 602A/602B) may control the RF or wireless transceiver 602A or 602B to receive, send, broadcast or transmit signals or data.

The embodiments are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other communication systems. Another example of a suitable communications system is the <NUM> concept. It is assumed that network architecture in <NUM> will be quite similar to that of the LTE-advanced. <NUM> is likely to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

It should be appreciated that future networks will most probably utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head.

Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Implementations may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Implementations of the various techniques may also include implementations provided via transitory signals or media, and/or programs and/or software implementations that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, implementations may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

Furthermore, implementations of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers,. ) embedded in physical objects at different locations. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various implementations of techniques described herein may be provided via one or more of these technologies.

To provide for interaction with a user, implementations may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a user interface, such as a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer.

Claim 1:
An apparatus, comprising:
means for receiving uplink resource information from a network describing a plurality of uplink resources, wherein the uplink resource information is received with a plurality of downlink reference signals, each of the plurality of downlink reference signals being associated with a respective uplink resource of the plurality of uplink resources (<NUM>);
characterized by
means for determining, after receiving the uplink resource information and for at least one of the plurality of uplink resources, restrictions on user equipment resources associated with those at least one of the plurality of uplink resources, wherein the means for determining comprises at least one of means for performing a power determination operation to produce a value of an output power reduction associated with that uplink resource and means for performing a duty cycle determination operation to produce a value of a minimum duty cycle associated with that uplink resource (<NUM>);
means for selecting at least one of the plurality of uplink resources based on the restrictions on the user equipment resources associated with the at least one of the plurality of uplink resources, wherein means for selecting at least one of the plurality of uplink resources comprises:
means for performing a power measurement operation on each of the plurality of downlink reference signals to produce a plurality of reference signal received power values, each of the plurality of reference signal received power values corresponding to a respective uplink resource of the plurality of uplink resources, and
means for adjusting, for each of the plurality of downlink reference signals, the reference signal received power value of the plurality of reference signal received power values to produce an adjusted reference signal received power value corresponding to the reference signal received power value, the adjusted reference signal received power value being based on the restrictions on the user equipment resources (<NUM>); and
means for transmitting data using the at least one of the plurality of selected uplink resources.