Patent Description:
11ax standard development, Random Access (RA) should be designed to allow a large number of STAs to transmit a RA request with reasonable complexity in terms of time and frequency resources.

There are two main trends currently discussed in standard development process: PHY (Physical layer device) based RA and MAC (Medium Access Controller) based RA. MAC based RA translates into a direct transmission of RA data, where the resources are allocated to a large number of STAs and each STA can choose randomly an available resource to transmit on. PHY based RA <NUM> as shown in <FIG> is performed in two steps: <NUM>) Trigger Frame for RA (TFR) <NUM> is a frame that indicates that RA should be transmitted in the next uplink frame (including description of allocated resources). When TFR <NUM> is sent by AP, STA responds with a single bit indication of RA request <NUM>. <NUM>) In order to complete the RA procedure an additional TFR <NUM> is sent and STA responds with RA data transmission <NUM>. After completion of these two steps AP transmits a trigger frame (TF) <NUM> and STA transmits data <NUM>.

Although PHY RA can be more efficient in some scenarios, in dense network this solution is not efficient enough. Random Access procedure can require many resources, especially in dense network scenarios. Current discussions in the <NUM>. 11ax upcoming standard introduce several types of Random Access procedure. However, the required time and frequency resources are still too high to provide an efficient solution to a large number of STAs. Moreover, in some Random Access solutions the same resources are allocated for multiple clients and thus collision probability is very high.

When the number of STAs is large the probability of collision is extremely high and may lead to a very inefficient RA procedure. Moreover, the additional data required to indicate which allocation is requested <NUM> is a large overhead which makes both MAC and PHY RA procedures much longer in terms of time duration as shown in <FIG>. Hence, both options have no practical solution for a very dense network.

Document <CIT> shows a method and system for partitioning at least a subset of resources for random access attempts into a plurality of partitions. A network node, eNB, receives a transmission on a contention based resource in a partition, the partition being from a plurality of partitions configured by the network node; and responds to the transmission on the contention based resource within a time and using a priority based on the partition over which the transmission was received. A common PRACH preamble partition configuration, RACHconfigCommon, defining partition identifiers, partition mask indexes, start preambles is included as part of the system information block type <NUM>.

Document <CIT> shows a method and devices for transmitting and receiving data in a code division multiple access telecommunication system, comprising the steps of providing a random access time window comprising a plurality of random access slots for transmitting random access data from at least one first communication device to a second communication device, dividing a plurality of random access slots of the random access time window into at least two groups, and allocating the groups to respective priority classes, whereby the priority classes represent the transmission priorities of the random access data to be transmitted in the random access slots.

It is the object of the present application to provide a concept for an efficient communication initiation, in particular for a RA procedure, between an AP and a STA, in particular in dense network scenarios where the number of STAs is large.

This object is achieved by the features of the independent claims.

A basic idea of the present application is to reduce collision probability by allocating dedicated resources to a specific group of STAs, while the rest of the STAs can choose from the rest of the resources. For example, if every STA has a dedicated resource, the probability of a collision is zero. This basic idea is used with specific adaptation for RA purposes. RA groups are defined, where each group has a specific set of transmission parameters associated with this group. Different RA resources can be allocated for each RA group. Each STA may choose an RA group according to the transmission parameters associated with a specific RA group. Data resources will be allocated according to a RA group that was chosen for transmission of RA data.

The AP can choose different criteria for group definition according a network status and STAs that are currently associated with this AP. For example, possible criteria for group definition can be: Packet size or packet duration in time (a number of bits to be transmitted); Modulation and coding rate; Transmission scheme (special transmission techniques defined by standard); Number of antennas/streams; etc. Each group can be defined by a single criterion or by a combination thereof.

Such a novel technique improves the efficiency and minimizes the time required to complete a Random Access procedure along with lower collision probability.

The devices described herein may be applied in <NUM>. 11ax systems. 11ax standard development, control mechanisms, like random access (RA), acknowledgment (ACK), association request etc., are applied immediately after a trigger frame (TF) that is transmitted by the access point, also referred hereinafter as access point device. Thus the stations (STAs), also referred hereinafter as client devices, wait for the AP to trigger them. A Trigger Frame may be followed by one or more uplink (UL) frames, where each frame comprises a control signal transmitted by one or more STAs.

The devices described herein may perform random access procedures. Random access (RA) is a procedure that allows client type communication devices to request from an access point (AP) type communication device resources for transmission by use of a resource request and by another procedure to initiate an association procedure with the AP. In other words, this mechanism is usually applied by the client devices that need to request the resources. The client devices can achieve an association with a specific AP. Currently, in the <NUM>. 11ax standard, RA is applied immediately after a trigger frame (TF), which is transmitted by the AP. Thus the client devices wait for AP to trigger them (indicate the existence of a random access opportunity). A TF frame may be followed by several RA opportunities. Within each opportunity, clients can try to access the channel. For doing so they contend with each other.

The devices described herein may be configured to communicate using MAC based RA. In this technique, the RA is transmitted as regular data, including payload, where each client allocates its transmission within a single resource unit (RU) as defined in <NUM>. A RU is defined as a set of continuous subcarriers, e.g. <NUM>, over some period of time. The AP can decide to provide more than one RA frame triggered by a single TF. The specific frame and the RU within the frame can be chosen in a random way by each client type communication device. No distinguishing between the non-associated client type communication devices and associated client type communication devices is introduced and all the client type communication devices that try to transmit an RA, are allowed to choose any time/frequency resources allocated for the current RA opportunity. A random access block typically comprises a plurality of frequency subcarriers and a plurality of time slots. A frequency section comprises at least one such frequency subcarrier but typically a plurality of neighboring (the spacing between two neighboring frequency subcarriers depends on what is defined by the underlying communication system) frequency subcarriers.

The devices described herein may be configured to to communicate using PHY based RA. PHY based RA is transmitted as PHY signaling and does not include any higher layer (MAC or above) payload. Several communication techniques regarding PHY based RA, where the RA data is a simple PHY signaling that informs the AP that a specific client type communication device wants resources, are available. The RA data is thus very short and allows a higher number of client type communication devices to be allocated within a single RA frame.

The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender) with a radio carrier frequency lying in a range of about <NUM> to <NUM>. The frequency range may correspond to frequencies of alternating current electrical signals used to produce and detect radio waves.

The devices described herein may be applied in OFDM and OFDMA systems. OFDM and OFDMA are schemes for encoding digital data on multiple carrier frequencies. A large number of closely spaced orthogonal sub-carrier signals may be used to carry data. Due to the orthogonality of the sub-carriers crosstalk between sub-carriers may be suppressed.

In order to describe the present application in detail, the following terms, abbreviations and notations will be used:.

According to a first aspect, the present application relates to a non-transitory computer-readable media storing computer instructions for an access point (AP), which when executed by one or more processors, cause the one or more processors to perform the steps of: transmit, by the AP, a first data packet indicating a set of groups, wherein each group is associated with a specific set of transmission parameters, transmit, by the AP, a second data packet by using a trigger frame for RA (TFR), indicating an allocation for at least part of the groups; and receive, by the AP, a response frame using at least part of random access (RA) resources selected by the STA for the at least part of the groups.

Such an AP indicating a grouping of transmission parameters to the STA reduces collision probability and thus reduces time required for RA procedure. Smart grouping allows collision probability management according to network requirements. Using transmission parameters for group definition allows reduction of RA data and thus reduces overall time of RA procedure.

In a first possible implementation form of the AP according to the first aspect, the AP comprises a controller configured to allocate different RA resources for each group.

Allocating different RA resources for each group provides the advantage that competition of STAs using transmission parameters of a first group with STAs using transmission parameters of a second group can be avoided, thereby reducing collision probability.

In a second possible implementation form of the AP according to the first aspect as such or according to the first implementation form of the first aspect, the controller is configured to allocate RA resources for transmission of RA data according to the at least part of RA resources used by the STA.

Allocating RA resources for transmission of RA data according to the (at least part of) RA resources used by the STA provides an easy allocation mechanism for the RA resources.

In a third possible implementation form of the AP according to the first aspect as such or according to any one of the preceding implementation forms of the first aspect, the set of groups is based on at least one of the following criteria: number of bits to be transmitted, modulation and coding rate, transmission scheme, number of antennas and/or data streams.

This provides the advantage that the grouping can be flexible adapted to the required transmission parameters. This can be performed at run-time or the grouping can be predetermined, e.g. from off-line trials.

In a fourth possible implementation form of the AP according to the first aspect as such or according to any one of the preceding implementation forms of the first aspect, the transceiver is configured to transmit the second data packet by using a trigger frame for RA (TFR).

This provides the advantage that the TFR frame can be according to the definition of the standard, e.g. IEEE <NUM>. , the standard can be reused when only adding the first data packet with the definition of the set of groups.

In a fifth possible implementation form of the AP according to the first aspect as such or according to any one of the preceding implementation forms of the first aspect, the transceiver is configured to operate according to a MAC based RA procedure or according to a PHY based RA procedure.

This provides the advantage that existing implementations for MAC based RA procedure or PHY based RA procedure can be reused with slight modifications with respect to the definitions of the groups of transmission parameters.

According to a second aspect, the present application relates to a non-transitory computer-readable media storing computer instructions for a client device (STA), which when executed by one or more processors, cause the one or more processors to perform the steps of: receive, by the STA from the AP, a first data packet indicating a set of groups wherein each group is associated with a specific set of transmission parameters; receive, by the STA from the AP, a second data packet indicating an allocation for at least part of the groups; select, by the STA, random access (RA) resources for the at least part of the groups and transmit a response frame using at least part of the RA resources allocated for the at least part of the groups.

Such an STA receiving an indication of a grouping of transmission parameters from the AP reduces collision probability and thus reduces time required for RA procedure. Smart grouping allows collision probability management according to network requirements. Using transmission parameters for group definition allows reduction of RA data and thus reduces overall time of RA procedure.

In a first possible implementation form of the STA according to the second aspect, the transceiver is configured to receive the second data packet as trigger frame for RA (TFR) and/or to transmit the response frame as RA request.

This provides the advantage that the TFR frame and/or the RA request can be according to the definition of the standard, e.g. IEEE <NUM>. , the standard can be reused when only adding the indication from the AP with the definition of the set of groups.

In a second possible implementation form of the STA according to the second aspect as such or according to the first implementation form of the second aspect, the controller is configured to select RA resources for a specific group based on the specific set of transmission parameters associated with the specific group.

Selecting RA resources for a specific group based on the specific set of transmission parameters associated with the specific group provides the advantage that competition of STAs using transmission parameters of a first group with STAs using transmission parameters of a second group can be avoided, thereby reducing collision probability.

In a third possible implementation form of the STA according to the second aspect as such or according to any one of the preceding implementation forms of the second aspect, the controller is configured to control the transceiver according to a MAC based RA procedure or according to a PHY based RA procedure.

In a fourth possible implementation form of the STA according to the third implementation form of the second aspect, the transceiver is configured for a MAC based RA procedure to transmit both, the RA Request and data by using the selected RA resources.

This provides the advantage that a number of data packets exchanged between STA and AP can be reduced, thereby improving efficiency.

In a fifth possible implementation form of the STA according to the third implementation form of the second aspect, the transceiver is configured for a PHY based RA procedure to transmit the RA Request using a single bit indication and to transmit data by using the selected RA resources.

This provides the advantage that transmitting the RA Request by using a single bit indication reduces collision probability due to the short time required for transmission.

Further embodiments of the present application will be described with respect to the following figures, in which:.

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa.

<FIG> shows a schematic diagram illustrating RA resources allocation with grouping <NUM> according to an implementation form.

The figure shows an exemplary grouping where an integer number of N resources <NUM> are grouped in an integer number of K groups <NUM>, <NUM>, <NUM>. For example, if there is a RA group with data payload limited by N bytes, every STA that transmits on the resource allocated for this group will be allocated data resources for up to N bytes. Using this method can avoid explicit indication of the required allocation and thus decreases an RA data payload and the time required to complete the RA procedure.

RA groups <NUM>, <NUM>, <NUM> can be defined, e.g. by the AP or predetermined by the network. Each group <NUM>, <NUM>, <NUM> can have a different set of transmission parameters associated with it, e.g. payload size, MCS (modulation and coding scheme), number of spatial streams, etc. Definition of groups can vary in time. Each STA can choose a single group to transmit RA data on the resources allocated to this group.

Using such a grouping <NUM> of resources <NUM> or partitioning of resources <NUM> into a set of groups <NUM>, <NUM>, <NUM> reduces collision probability in RA and reduces time required to complete the RA procedure.

<FIG> shows a schematic diagram illustrating a time diagram of grouping for PHY based RA <NUM> according to an implementation form. The PHY based RA procedure <NUM> may include the following blocks: AP <NUM> defines a set of groups, e.g. a number of K groups as shown in <FIG>. AP <NUM> advertises the definitions of the group within a (first) data packet, e.g. a broadcast packet <NUM>. AP <NUM> transmits a (second) data packet, e.g. a TFR <NUM> with specific allocation of resources for the defined group or part of them. STA <NUM> chooses relevant resources to transmit on a response frame, e.g. a RA request <NUM> using the chosen resources. AP <NUM> transmits a (third) data packet, e.g. a TF <NUM> with allocation of the resources for STA <NUM> according to the resources that were used for RA request <NUM>. STA <NUM> transmits a data packet <NUM>.

<FIG> shows a schematic diagram illustrating a time diagram of grouping for MAC based RA <NUM> according to an implementation form. The MAC based RA procedure <NUM> may include the following blocks: AP <NUM> defines a set of groups, e.g. a number of K groups as shown in <FIG>. AP <NUM> advertises the definitions of the group within a (first) data packet, e.g. a broadcast packet <NUM>. AP <NUM> transmits a (second) data packet, e.g. a TFR <NUM> with specific allocation of resources for the defined group or part of them. STA <NUM> chooses relevant resources to transmit on a response frame <NUM> with parameters defined for a specific group.

<FIG> shows a schematic diagram illustrating a grouping according to an implementation form. <FIG> shows a scenario where three main types of STAs are associated with an AP: A lot of STAs (of a first type) transmit voice data, where a low amount of data has to be transmitted, thus short packets (short duration) with low modulation. Few STAs (of a second type) transmit video/images, where a large amount of data has to be transmitted, thus long packets (long duration) with high modulation. All the other STAs are assigned to a third type.

For this scenario, the AP may define three groups: a first group <NUM> for short duration data, a second group <NUM> for long duration data and a third (general) group <NUM> for all other kinds of data. According to a potential number of STAs in each group, in one implementation AP may allocate more resources <NUM> to the group of short duration <NUM> in order to accommodate a large number of STAs.

<FIG> shows a block diagram illustrating an AP <NUM> for communicating with a STA according to an implementation form. The AP <NUM> includes a transceiver <NUM> and an optional controller <NUM>. The transceiver <NUM> is configured to transmit <NUM> a first data packet, e.g. a data packet <NUM> as described above with respect to <FIG> and <FIG> indicating a set of groups, e.g. a set of groups <NUM> as described above with respect to <FIG>, wherein each group <NUM>, <NUM>, <NUM> is associated with a specific set of transmission parameters, e.g. packet size or packet duration in time such as a number of bits to be transmitted, modulation and coding rate, transmission scheme, number of antennas/streams; etc. The transceiver <NUM> is configured to transmit <NUM> a second data packet, e.g. a data packet <NUM> as described above with respect to <FIG> and <FIG> indicating an allocation for at least part of the groups <NUM>, <NUM>, <NUM>. The transceiver <NUM> is further configured to receive <NUM> a response frame, e.g. a frame <NUM>, <NUM> as described above with respect to <FIG> and <FIG>, using at least part of random access (RA) resources selected by the STA for the at least part of the groups <NUM>, <NUM>, <NUM>.

The controller <NUM> may allocate different RA resources <NUM> for each group <NUM>, <NUM>, <NUM> The controller <NUM> may allocate RA resources <NUM> for transmission of RA data according to the at least part of RA resources used by the STA. The set of groups <NUM> may be based on one or more of the following criteria: number of bits to be transmitted, modulation and coding rate, transmission scheme, number of antennas and/or data streams.

The transceiver <NUM> may transmit the second data packet <NUM> by using a trigger frame for RA (TFR), e.g. a TFR <NUM> as described above with respect to <FIG> and <FIG>. The transceiver <NUM> may operate according to a MAC based RA procedure <NUM>, e.g. as described above with respect to <FIG> or according to a PHY based RA procedure <NUM>, e.g. as described above with respect to <FIG>.

<FIG> shows a block diagram illustrating a client device (STA) <NUM> for communicating with an access point device (AP) according to an implementation form. The STA <NUM> includes a transceiver <NUM> and a controller <NUM>.

The transceiver <NUM> is configured to receive <NUM> from the AP a first data packet, e.g. a data packet <NUM> as described above with respect to <FIG> and <FIG>, indicating a set of groups, e.g. a set of groups <NUM> as described above with respect to <FIG>, wherein each group <NUM>, <NUM>, <NUM> is associated with a specific set of transmission parameters, e.g. packet size or packet duration in time such as a number of bits to be transmitted, modulation and coding rate, transmission scheme, number of antennas/streams; etc. The transceiver <NUM> is configured to receive <NUM> from the AP a second data packet, e.g. a data packet <NUM> as described above with respect to <FIG> and <FIG>, indicating an allocation for at least part of the groups <NUM>, <NUM>, <NUM>.

The controller <NUM> is configured to select random access (RA) resources for the at least part of the groups and to control the transceiver <NUM> transmitting <NUM> a response frame, e.g. a frame <NUM>, <NUM> as described above with respect to <FIG> and <FIG>, using at least part of the RA resources allocated for the at least part of the groups <NUM>, <NUM>, <NUM>.

The transceiver <NUM> may be configured to receive <NUM> the second data packet <NUM> as trigger frame for RA (TFR). The transceiver <NUM> may be configured to transmit <NUM> the response frame <NUM> as RA request.

The controller <NUM> may select RA resources <NUM> for a specific group, e.g. a group <NUM> shown in <FIG>, based on the specific set of transmission parameters, e.g. the transmission parameters associated with long duration data such as video/images <NUM> associated with the specific group <NUM>.

The controller <NUM> may control the transceiver <NUM> according to a MAC based RA procedure <NUM>, e.g. as shown in <FIG>. Alternatively, the controller <NUM> may control the transceiver <NUM> according to a PHY based RA procedure <NUM>, e.g. as shown in <FIG>.

The transceiver <NUM> may be configured for a MAC based RA procedure <NUM>, e.g. as illustrated in <FIG>, to transmit both, the RA Request and data <NUM> by using the selected RA resources. Alternatively, the transceiver may be configured for a PHY based RA procedure <NUM>, e.g. as illustrated in <FIG>, to transmit the RA Request <NUM> using a single bit indication and to transmit data <NUM> by using the selected RA resources.

<FIG> shows a schematic diagram illustrating a transmission method <NUM> for indicating a grouping of transmission parameters according to an implementation form. The transmission method <NUM> includes the following blocks which may correspond to the respective functionalities of the transceiver <NUM> of the AP <NUM> described above with respect to <FIG>: A first block <NUM> includes: transmitting, by an access point device (AP) <NUM>, a first data packet <NUM> indicating a set of groups <NUM>, wherein each group <NUM>, <NUM>, <NUM> is associated with a specific set of transmission parameters. A second block <NUM> includes: transmitting, by the AP <NUM>, a second data packet <NUM> indicating an allocation for at least part of the groups <NUM>, <NUM>, <NUM>. A third block <NUM> includes: receiving, by the AP <NUM>, a response frame <NUM>, <NUM> using at least part of random access (RA) resources selected by a client device (STA) <NUM> for the at least part of the groups <NUM>, <NUM>, <NUM>.

The method <NUM> may also include other functionalities of the AP described above with respect to <FIG>, for example: allocating, by the AP <NUM>, different RA resources <NUM> for each group <NUM>, <NUM>, <NUM>, etc..

<FIG> shows a schematic diagram illustrating a reception method <NUM> for receiving an indication of a grouping of transmission parameters according to an implementation form.

The reception method <NUM> includes the following blocks which may correspond to the respective functionalities of the transceiver <NUM> and the controller <NUM> of the STA <NUM> described above with respect to <FIG>: A first block <NUM> includes: receiving, from an access point device (AP) <NUM>, a first data packet <NUM> indicating a set of groups <NUM>, wherein each group <NUM>, <NUM>, <NUM> is associated with a specific set of transmission parameters. A second block <NUM> includes: receiving, from the AP <NUM>, a second data packet <NUM> indicating an allocation for at least part of the groups <NUM>, <NUM>, <NUM>. A third block <NUM> includes: selecting <NUM> RA resources for the at least part of the groups <NUM>, <NUM>, <NUM>. A fourth block <NUM> includes: transmitting a response frame <NUM>, <NUM> using at least part of the RA resources allocated for the at least part of the groups <NUM>, <NUM> and <NUM>.

The method <NUM> may also include other functionalities of the STA described above with respect to <FIG>, for example: receiving the second data packet as a trigger frame for RA and/or transmitting the response frame as RA request, etc..

The above-described grouping requires the AP to signal to the STAs what grouping is used; it may therefore become part of the standardization, e.g. of IEEE <NUM>. 11ax standard.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the steps of the methods <NUM>, <NUM> described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the performing and computing steps described herein, in particular the methods <NUM>, <NUM> described above.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Claim 1:
A non-transitory computer-readable media storing computer instructions for an access point, AP, which when executed by one or more processors, cause the one or more processors to perform the steps of:
transmit, by the AP, a broadcast packet (<NUM>) indicating a set of groups (<NUM>), wherein each group (<NUM>,<NUM>, <NUM>) is associated with a specific set of transmission parameters;
transmit, by the AP, a second packet by using a trigger frame for random access, TFR, indicating an allocation of resources for at least part of the groups (<NUM>, <NUM>,<NUM>); and
receive, by the AP, a response frame (<NUM>, <NUM>) using at least part of random access, RA, resources selected by a station, STA, (<NUM>) for the at least part of the groups (<NUM>, <NUM>, <NUM>).