Patent Description:
In recent communication networks, communications on unlicensed spectrum have been proposed to improve communication capacity. For example, a random access channel (RACH) is shared by terminal devices to request access to networks for call set-up and burst data transmission. Since the RACH is shared, it is possible that two or more terminal devices transmit at the same time and their transmissions collide. This is known as contention. If the terminal device does not get response, it performs the random access request again. Such transmission collisions may incur undesirable failure of random access and unexpected delay in transmission. <NPL>, relates to enhancing transmission opportunities for msg1. <NPL>, relates to channel access rules for NR-U.

Generally, embodiments of the present disclosure relate to an apparatus, method and computer readable medium as set out in the appended set of claims. The device is further caused to determine the number of transmission opportunities granted for the device based on the indication in response to determining that the random access response comprises the preamble of the device. The device is yet caused to determine a set of transmission resources for the device based at least in part on the number of the transmission opportunities.

In a second aspect, there is provided a device. The device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the device to receive, from a further device, a random access request comprising a preamble of the further device. The device is also caused to generate a random access response to the random access request in response to the random access request being accepted. The random access response comprises the preamble of the further device. The device is further caused to transmit the random access response to the further device. The random access response comprises an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded and a transmission resource for one transmission opportunity.

In a third aspect, there is provided a method. The method comprises transmitting a random access request from a first device to a second device. The random access request comprises a preamble of the first device. The method also comprises receiving a random access response to the random access request from the second device. The random access response comprises an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded. The method further comprises in response to determining that the random access response comprises the preamble of the first device, determining the number of transmission opportunities granted for the first device based on the indication. The method yet comprises determining a set of transmission resources for the first device based at least in part on the number of the transmission opportunities.

In a fourth aspect, there is provided a method. The method comprises receiving, from a first device and at a second device, a random access request comprising a preamble of the first device. The method also comprises in response to the random access request being accepted, generating a random access response to the random access request. The random access response comprises the preamble of the first device. The method further comprises transmitting the random access response to the first device. The random access response comprises an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded and a transmission resource for one transmission opportunity.

In a fifth aspect, there is provided an apparatus. The apparatus comprises means for transmitting a random access request from a first device to a second device. The random access request comprises a preamble of the first device. The apparatus also comprises means for receiving a random access response to the random access request from the second device. The random access response comprises an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded. The apparatus further comprises means for in response to determining that the random access response comprises the preamble of the first device, determining the number of transmission opportunities granted for the first device based on the random access response. The apparatus yet comprises means for determining a set of transmission resources for the first device based at least in part on the number of the transmission opportunities.

In a sixth aspect, there is provided an apparatus. The apparatus comprises means for receiving, from a first device and at a second device, a random access request comprising a preamble of the first device. The apparatus also comprises means for in response to the random access request being accepted, generating a random access response to the random access request. The random access response comprises the preamble of the first device. The apparatus further comprises means for transmitting the random access response to the first device. The random access response comprises an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded and a transmission resource for one transmission opportunity.

In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to any one of the above third to fourth aspects.

As used herein, the term "communication network" refers to a network following any suitable communication standards, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a user equipment and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (<NUM>), the second generation (<NUM>), <NUM>, <NUM>, the third generation (<NUM>), the fourth generation (<NUM>), <NUM>, the future fifth generation (<NUM>) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term "network device" refers to a node in a communication network via which a user equipment accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.

As mentioned above, several mechanisms for RACH have been proposed. For example, <NUM>-step RACH procedure and <NUM>-step RACH procedure may be supported for in communications, for example, new radio unlicensed (NR-U) networks. The term "<NUM>-step RACH" used herein refers to the procedure which can complete contention-based RACH (CBRA) in two steps. One additional benefit of <NUM>-step RACH is less listen-before-talk (LBT) impact with the reduced number of messages. Further, in order to alleviate the impact of LBT failures, additional opportunities for the RACH messages may be introduced.

In a conventional technology, the terminal device has to monitor a plurality of random access response (RAR) in order to obtain multiple opportunities, which may lead to extra power consumption. In other conventional technology, the terminal device may receive multiple individual RARs for the same preamble in one protocol data unit (PDU), which may cause too many overheads. Some conventional technologies require the network device to configure the multiple opportunities semi-statically, which may lack of flexibility. Further, in semi-statically configured technologies, it is required to assume worst case as the channel availability status is quite dynamic and waste too much uplink resources. In some conventional technologies, the format for the RAR may be changed to indicate multiple uplink grants within each individual RAR, which may lack of backward compatibility. Thus, a new solution for providing multiple transmission opportunities is needed.

According to embodiments of the present disclosure, the network device transmits the random access response which comprises an indication as to the number of transmission opportunities. If the random access response comprises the preamble of the terminal device, the indication as to the number of transmission opportunities is applied to the terminal device. In this way, overheads are saved and the flexibility is improved.

<FIG> illustrates a schematic diagram of a communication system <NUM> in which embodiments of the present disclosure can be implemented. The communication system <NUM> comprises the first devices <NUM> and the second device <NUM>. For the purpose of illustrations, the first devices <NUM> may be referred to as the terminal device <NUM> and the second device <NUM> may be referred to as the network device <NUM> hereinafter. It should be noted that the first devices and the second devices are interchangeable. For example, the procedures which are described to be implemented at the terminal device may also be able to be implemented at the network device and the procedures which are described to be implemented at the network device may also be able to be implemented at the terminal device.

The link from the second device <NUM> to the first devices <NUM> may be referred to as the "down link" and the link from the first devices <NUM> to the second device <NUM> may be referred to as the "uplink link.

The communication system <NUM>, which is a part of a communication network, comprises terminal devices <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-N (collectively referred to as "terminal device(s) <NUM>" where N is an integer number). The communication system <NUM> comprises one or more network devices, for example, a network device <NUM>. It should be understood that the communication system <NUM> may also comprise other elements which are omitted for the purpose of clarity. It is to be understood that the numbers of terminal devices and network devices shown in <FIG> are given for the purpose of illustration without suggesting any limitations. The terminal devices <NUM> and the network device <NUM> may communicate with each other.

It is to be understood that the number of network devices and terminal devices is only for the purpose of illustration without suggesting any limitations. The system <NUM> may include any suitable number of network devices and terminal devices adapted for implementing embodiments of the present disclosure.

Communications in the communication system <NUM> may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the first generation (<NUM>), the second generation (<NUM>), the third generation (<NUM>), the fourth generation (<NUM>) and the fifth generation (<NUM>) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) <NUM> and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

<FIG> illustrates a schematic diagram of interactions <NUM> in accordance with embodiments of the present disclosure. The interactions <NUM> may be implemented at any suitable devices. Only for the purpose of illustrations, the interactions <NUM> are described to be implemented at the terminal device <NUM>-<NUM> and the network device <NUM>.

The terminal device <NUM>-<NUM> transmits <NUM> a random access request to the network device <NUM>. The random access request comprises a preamble of the terminal device <NUM>-<NUM>. In some embodiments, the random access may be triggered by the network device <NUM>. Alternatively, the random access may be triggered by higher layer, for example, reestablishment of radio resource control. In some embodiments, the network device <NUM> may inform the terminal device <NUM>-<NUM> of the index of the preamble in downlink control information.

Alternatively, the terminal device <NUM>-<NUM> may choose the preamble by itself. In some embodiments, the terminal device <NUM>-<NUM> may determine a physical random access channel (PRACH) to transmit the random access request.

The network device <NUM> generates <NUM> the random access response to the random access request. If the random access request from the terminal device <NUM>-<NUM> is accepted, the random access response comprises the preamble of the terminal device <NUM>-<NUM>. The random access response also comprises information of the transmission resource granted for the terminal device <NUM>-<NUM>. For example, if the transmission resources are in time domain, the random access response may comprise information about one or more time slots which can be used by the terminal device <NUM>-<NUM> to perform uplink transmission. Alternatively, if the transmission resources are in frequency domain, the random access response may comprise information about one or more physical resource blocks which can be used by the terminal device to perform uplink transmission.

The random access response comprises an indication (also referred to as "multiple opportunities indication") as to the number of transmission opportunities for the terminal device <NUM>-<NUM>. The random access response comprises an indication as to the number of transmission opportunities granted for a set of terminal devices which are allowed for random access. If the random access response are transmitted to several terminal devices, the multiple opportunities indication are applied to the set of terminal devices of which random access requests are responded.

In some embodiments, the network device <NUM> may determine <NUM> the number of transmission opportunities based on the channel status between the network device <NUM> and the terminal device <NUM>-<NUM>. In some embodiments, the multiple opportunities indication may indicate multiple time domain opportunities with a time domain offset from the uplink grant. Alternatively, the indication may indicate multiple frequency domain opportunities with a frequency offset to the resources (PRBs) provided in the uplink grant.

<FIG> illustrate schematic diagrams of the random access response in medium access control (MAC) PDU <NUM>. The MAC PDU <NUM> may comprise MAC sub PDU <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-M (where M is an integer number). The MAC subPDU may comprise one of: a MAC subheader with Backoff Indicator only; a MAC subheader with random access preamble identifier (RAPID) only (i.e. acknowledgment for system information (SI) request); a MAC subheader with RAPID and MAC RAR.

As shown in <FIG>, the MAC sub PDU <NUM>-<NUM> has an E/T/R/BI subheader <NUM>, the MAC sub PDU <NUM>-<NUM> has a subheader <NUM>-<NUM>, and the MAC sub PDU <NUM>-<NUM> has a subheader <NUM>-<NUM> and a MAC RAR <NUM>. As shown in <FIG>, the subheader <NUM> with Backoff Indicator has five header fields: E field <NUM>, T field <NUM>, R field <NUM>, R field <NUM> and Backoff Indicator field <NUM>. The subheader <NUM> with Backoff Indicator may only be placed at the beginning of the MAC PDU <NUM>. As shown in <FIG>, the subheader with RAPID <NUM>-<NUM> has three header fields: E field <NUM>, T field <NUM>, and RAPID field <NUM>. The reserved bits in the subheader <NUM> may be used to indicate the number of transmission opportunities. The legacy terminal devices are not impacted since the legacy terminal devices may take it as no back off.

Table <NUM> below shows the relationship between reserved bits and the number of transmission opportunities. It should be noted that the values and numbers shown in <FIG> are only examples not limitations.

In this way, the multiple opportunities indication is applicable to all the UL grants in each individual RAR and the size of each individual RAR within the RAR PDU remains unchanged. It saves overhead comparing to duplicating the individual RARs in the PDU or sending them in multiple RARs. It may also provide more flexibility comparing to semi-statically configured via RRC since the channel busy/idle status is quite dynamic.

The network device <NUM> transmits <NUM> the random access response to the terminal device <NUM>-<NUM>. In some embodiments, the terminal device may monitor the physical downlink control channel (PDCCH) to receive the random access response. The terminal device <NUM>-<NUM> determines <NUM> whether the random access is responded. For example, if the preamble ID (identity) of the terminal device <NUM>-<NUM> is in the random access response, the terminal device <NUM>-<NUM> may determine that the random access is responded. If the random access response comprises the preamble of the terminal device <NUM>-<NUM>, the terminal device <NUM>-<NUM> determines <NUM> the number of transmission opportunities from the random access response. For example, as mentioned above, if the subheader <NUM> comprises the indication "<NUM>", the terminal device <NUM>-<NUM> may determine that there are three transmission opportunities.

The terminal device <NUM>-<NUM> determines <NUM> the transmission resource (also known as the "UL grant") from the random access response. For example, the terminal device <NUM>-<NUM> may determine the transmission resource from the MAC RAR (for example, the MAC RAR <NUM>). The random access response may comprise several bits to assign time and/or frequency resources to the terminal device <NUM>-<NUM>.

In some embodiments, the network device <NUM> may transmit <NUM> the resource offset to the terminal device <NUM>-<NUM> via the RRC signaling before the Random Access procedure. Alternatively, the resource offset may be pre-configured to the terminal device <NUM>-<NUM>. For example, the resource offset may be defined in the specification.

In some embodiments, the resource offset may be in frequency domain. For example, the frequency offset may be <NUM>. Alternatively, the resource offset may be in time domain. The terminal device <NUM>-<NUM> may determine <NUM> the resource offset from the information received via the RRC signaling. In some embodiments, the terminal device may also determine <NUM> the resource offset in the pre-configured information. In some embodiments, the multiple time domain opportunities are continuous uplink grant following the UL grant indicated in the random access response without any gap/offset between the opportunities.

The terminal device <NUM>-<NUM> determines <NUM> the set of transmission resources based at least in part on the number of transmission opportunities. The terminal device <NUM>-<NUM> determines the set of transmission resources based on the number of transmission opportunities and the resource offset.

<FIG> illustrates a flow chart of a method <NUM> in accordance with embodiments of the present disclosure. The method <NUM> may be implemented at any suitable devices. Only for the purpose of illustrations, the method <NUM> is described to be implemented at the terminal device <NUM>-<NUM>. It should be noted that the method <NUM> may also be implemented at the network device <NUM>.

At block <NUM>, the terminal device <NUM>-<NUM> transmits a random access request to the network device <NUM>. The random access request comprises a preamble of the terminal device <NUM>-<NUM>. The random access may be triggered by the network device <NUM>. Alternatively, the random access may be triggered by higher layer, for example, reestablishment of radio resource control. In some embodiments, the network device <NUM> may inform the terminal device <NUM>-<NUM> of the index of the preamble in downlink control information.

Alternatively, the terminal device <NUM>-<NUM> may choose the preamble by itself. The terminal device <NUM>-<NUM> may determine a physical random access channel (PRACH) to transmit the random access request.

At block <NUM>, the terminal device <NUM>-<NUM> receives the random access response from the network device <NUM>. The terminal device may monitor the physical downlink control channel (PDCCH) to receive the random access response. If the random access request from the terminal device <NUM>-<NUM> is responded, the random access response comprises the preamble ID of the terminal device <NUM>-<NUM>. In some embodiments, the random access response comprises an indication as to the number of transmission opportunities granted for a set of terminal devices of which random access requests are responded. If the random access response are transmitted to several terminal devices, the multiple opportunities indication are applied to the set of terminal devices of which random access requests are responded.

At block <NUM>, the terminal device <NUM>-<NUM> determines the number of transmission opportunities based on the random access response if the preamble ID of the terminal device <NUM>-<NUM> is in the random access response. The random access response comprises an indication as to the number of transmission opportunities for the terminal device <NUM>-<NUM>.

In some embodiments, the indication may indicate multiple time domain opportunities with a time domain offset from the uplink grant. In some embodiments, the multiple time domain opportunities are continuous uplink grant following the UL grant indicated in the random access response. Alternatively, the indication may indicate multiple frequency domain opportunities with a frequency offset to the resources (PRBs) provided in the uplink grant. For example, as mentioned above, if the subheader comprises the indication "<NUM>", the terminal device <NUM>-<NUM> may determine that there are three transmission opportunities.

At block <NUM>, the terminal device <NUM>-<NUM> determines the set of transmission resources based at least in part on the number of transmission opportunities. The terminal device <NUM>-<NUM> determines the set of transmission resources based on, the transmission resource, the number of transmission opportunities and the resource offset. The terminal device <NUM>-<NUM> determines the transmission resource from the random access response. For example, the terminal device <NUM>-<NUM> may determine the transmission resource from the MAC RAR. The random access response may comprise several bits to assign time and/or frequency resources to the terminal device <NUM>-<NUM>.

In some embodiments, the terminal device <NUM>-<NUM> may receive the resource offset from the network device <NUM> via the RRC signaling. Alternatively, the resource offset may be pre-configured to the terminal device <NUM>-<NUM>. For example, the resource offset may be defined in the specification. In some embodiments, the resource offset may be in frequency domain. For example, the frequency offset may be <NUM>. Alternatively, the resource offset may be in time domain. The terminal device <NUM>-<NUM> may determine <NUM> the resource offset from the information received via the RRC signaling. In some embodiments, the terminal device may also determine <NUM> the resource offset in the pre-configured information.

<FIG> illustrates a flow chart of a <NUM> in accordance with embodiments useful for understanding the present disclosure. The method <NUM> may be implemented at any suitable devices. Only for the purpose of illustrations, the method <NUM> is described to be implemented at the network device <NUM>. It should be noted that the method <NUM> may also be implemented at the terminal device <NUM>-<NUM>.

At block <NUM>, the network device <NUM> receives a random access request from the terminal device <NUM>-<NUM>. The random access request comprises a preamble of the terminal device <NUM>-<NUM>. In some embodiments, the random access may be triggered by the network device <NUM>. Alternatively, the random access may be triggered by higher layer, for example, reestablishment of radio resource control. In some embodiments, the network device <NUM> may inform the terminal device <NUM>-<NUM> of the index of the preamble in downlink control information. The network device <NUM> may receive multiple random access requests from multiple terminal devices.

At block <NUM>, the network device <NUM> generates <NUM> the random access response to the random access request. If the random access request from the terminal device <NUM>-<NUM> is responded, the random access response comprises the preamble ID of the terminal device <NUM>-<NUM>.

The random access response also comprises information of the transmission resource granted for the terminal device <NUM>-<NUM>. For example, if the transmission resources are in time domain, the random access response may comprise information about one or more time slots which can be used by the terminal device <NUM>-<NUM> to perform uplink transmission. Alternatively, if the transmission resources are in frequency domain, the random access response may comprise information about one or more physical resource blocks which can be used by the terminal device to perform uplink transmission.

The random access response comprises an indication as to the number of transmission opportunities for the terminal device <NUM>-<NUM>. The random access response comprises an indication as to the number of transmission opportunities granted for a set of terminal devices of which random access requests are responded. If the random access response are transmitted to several terminal devices, the multiple opportunities indication are applied to the set of terminal devices of which random access requests are responded.

In some embodiments, the network device <NUM> may determine the number of transmission opportunities based on the channel status between the network device <NUM> and the terminal device <NUM>-<NUM>. In some embodiments, the indication may indicate multiple time domain opportunities with a time domain offset from the uplink grant. Alternatively, the indication may indicate multiple frequency domain opportunities with a frequency offset to the resources (PRBs) provided in the uplink grant.

At block <NUM>, the network device <NUM> transmits the random access response. For example, the network device <NUM> may transmit the random access response on the PDCCH. In some embodiments, the network device <NUM> may transmit <NUM> the resource offset to the terminal device <NUM>-<NUM> via the RRC signaling. In some embodiments, the resource offset may be in frequency domain. For example, the frequency offset may be <NUM>. Alternatively, the resource offset may be in time domain.

In some embodiments, an apparatus for performing the method <NUM> (for example, the terminal device <NUM>-<NUM>) may comprise respective means for performing the corresponding steps in the method <NUM>. These means may be implemented in any suitable manners. For example, it can be implemented by circuitry or software modules.

<FIG> is a simplified block diagram of a device <NUM> that is suitable for implementing embodiments of the present disclosure. The device <NUM> may be provided to implement the communication device, for example the network device <NUM> or the terminal devices <NUM> as shown in <FIG>. As shown, the device <NUM> includes one or more processors <NUM>, one or more memories <NUM> coupled to the processor <NUM>, and one or more communication module (for example, transmitters and/or receivers (TX/RX)) <NUM> coupled to the processor <NUM>.

The device <NUM> may have comprising the preamble of the first device; and means for transmitting the random access response to the first device, the random access response comprising: an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded and a transmission resource for one transmission opportunity.

In some embodiments, the apparatus further comprises: means for transmitting information to the first device via radio resource signaling, the information comprising a resource offset for determining a set of transmission resources for the transmission opportunities.

In some embodiments, the set of transmission resources and the resource offset are in time domain.

In some embodiments, the set of transmission resources and the resource offset are in frequency domain.

In some embodiments, the first device is a terminal device and the second device is a network device.

In some embodiments, the apparatus further comprises: means for determining the number of the transmission opportunities granted for the first device based on a channel status between the first and second devices.

In some embodiments, the program <NUM> may be tangibly contained in a computer readable medium which may be included in the device <NUM> (such as in the memory <NUM>) or other storage devices that are accessible by the device <NUM>.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods <NUM> and <NUM> as described above with reference to <FIG>. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Claim 1:
An apparatus comprising:
means for transmitting a random access request from a first device to a second device, the random access request comprising a preamble of the first device;
means for receiving a random access response to the random access request from the second device, the random access response comprising an indication as to the number of transmission opportunities granted for a set of devices of which random access requests are responded;
means for in response to determining that the random access response comprises the preamble of the first device, determining the number of transmission opportunities granted for the first device based on the indication; and
means for determining a set of transmission resources for the first device by:
determining a transmission resource for one transmission opportunity based on the random access response; and
determining the set of transmission resources for the transmission opportunities based on the transmission resource for one transmission opportunity, the number of the transmission opportunities and a resource offset.