Patent Description:
Generally, more and more applications that are using the wireless channels require high throughput and ultra-low latency. For example, Virtual Reality (VR) gaming requires typically 20msec as a maximum acceptable delay for high-quality user experience. In addition, Wi-Fi communication technology is not optimized for low latency, thus, both delay and delay jitter can be very large. Conventionally, in many cases, the experienced delays are much longer than the 20msec requirement mentioned above.

<CIT> discloses channel access method for data transmission, wireless communication method, and wireless communication terminal using the same. <CIT> discloses multi carrier listen before talk. Vu Long Hoang et al discloses a hybrid design of the two LBT types. Huawei et al, Coexistence and channel access for NR unlicensed band operations, <NPL>, which discloses coexistence and channel access for NR unlicensed band operations.

In addition, most of the conventional Wi-Fi devices use no scheduling protocols for channel access. The channel access is based on Carrier-Sense Multiple Access with Collision Avoidance (CSMA/CA) method, which may result in a long time period when the device is waiting for resources to be idle. <FIG> schematically illustrates the channel access problem in WiFi for a conventional access method. The conventional channel access method <NUM> defines that a device can transmit only when the primary channel <NUM> is idle. This means that, regardless of the status of the rest of the Bandwidth (BW) <NUM>, <NUM>, <NUM>, the availability of the primary channel <NUM> defines the probability to access the channel and transmit.

Furthermore, WiFi is a Test Driven Development (TDD) technology with no prescheduling algorithms. It means that only one device can transmit at a specific time slot and the decision regarding the transmission is done, immediately and before its start. In other words, there is no method that can promise successful channel access for a specific device at a specific time. This problem cannot be resolved due to backward compatibility that is mandatory in WiFi standards. Thus, if the device from the same network occupies the primary channel, there is no opportunity to transmit.

Moreover, the last version of the WiFi standard defined a spatial reuse method which allows the neighbor networks to carry out parallel transmissions using the same frequency resources if they do not interfere each other. However, this technique limits the power of the transmitted signal and also has several constraints that were introduced to preserve robustness. Thus, this conventional method is not optimized for latency reduction and cannot provide the desired efficiency for channel access.

In addition, another method that was already discussed as a candidate for channel access efficiency improvement is managing multiple primary channels where each channel can have its own BW or BWs related to different primary channels can overlap. This idea is based on an empirical statistic which shows that in most of the time periods there are free (idle) channels over the WiFi band (see the spectrogram for <NUM> <NUM> and the spectrogram for <NUM> <NUM> in <FIG> schematically illustrates channel status in WiFi bands for a conventional method <NUM>. Although this method can bring gain in latency reduction it has two main issues: implementation complexity is relatively high (multiple receive chains are required) and the status of each primary channel defines the channel access for the entire BW.

The conventional devices and methods have the disadvantages that they are either limited in their efficiency or require high additional complexity. Moreover, when the primary channel based rules are preserved, an available BW cannot be used, if the primary channel is busy.

In view of the above-mentioned problems and disadvantages, the present invention aims to improve the conventional devices and methods. The present invention has thereby the objective to provide a device, a system and a method for a wireless network. The present invention focuses on channel access efficiency for a single primary channel and provides a technique that can lead to latency reduction, and also, can be easily combined with other methods such as the multiple primary channels technique.

The objective of the present invention is achieved by the solution provided in the enclosed independent claims.

The main advantages of the embodiments of the invention can be summarized as follows:.

A first aspect of the invention provides a device for a wireless network comprising a single primary channel having a first predefined bandwidth configured as a common channel of operation for one or more devices associated with a specific access point, and a plurality of secondary channels having a second predefined bandwidth within the first predefined bandwidth, wherein the device is configured to execute a first Carrier-Sense Multiple Access with Collision Avoidance, CSMA/CA, instance associated with the primary channel to gain access to the primary channel, wherein a first back-off is generated; and execute a second CSMA/CA instance associated with one of the secondary channels to gain access to the secondary channel, wherein a second back-off is generated.

The device of the first aspect may address an issue related to the latency problem. In particular, the device of the first aspect may significantly reduce average delay and jitter in a Wi-Fi network for specific stations (STAs).

Moreover, the single primary channel may be configured as the common channel of operation such that it is the only channel that is known for all the one or more devices associated with the specific Access Point (AP).

The device may comprise a circuitry. The circuitry may comprise hardware and software. The hardware may comprise analog or digital circuitry, or both analog and digital circuitry. In some embodiments, the circuitry comprises one or more processors and a non-volatile memory connected to the one or more processors. The non-volatile memory may carry executable program code which, when executed by the one or more processors, causes the device to perform the operations or methods described herein.

In an implementation form of the first aspect, the device is further configured to execute a plurality of second CSMA/CA instances, each CSMA/CA instance being associated with a different secondary channel and a different maximum bandwidth.

In a further implementation form of the first aspect, the second back-off is decreased only when the secondary channel is free and the primary channel is occupied by another device.

In a further implementation form of the first aspect, is further configured to, if any back-off reaches zero, transmit data on the bandwidth defined for a determined channel, for which the back-off was generated.

In a further implementation form of the first aspect, the device is further configured to, if the primary channel is occupied by the other device and the second back-off reaches zero, transmit data on the secondary channel.

For example, the transmitted data may be any type of data. In some embodiments, the transmitted data may be, in particular, latency sensitive data.

In a further implementation form of the first aspect, the device is further configured to, if the primary channel become IDLE, refrain execution of at least one operation being currently performed.

In particular, the device may refrain an action, e.g., as soon as the primary channel is IDLE.

The device is further configured to, if the primary channel is occupied by another device being associated with another access point, determine the duration of a transmission by the other device on the primary channel.

The device is further configured to adjust total duration of all transmissions on the secondary channel to be shorter than or equal to the duration of the transmission by the other device on the primary channel.

In particular, the total duration of all transmissions (even if multiple packets are transmitted) should be adjusted.

In a further implementation form of the first aspect, the device is further configured to, when ending a transmission on the secondary channel, wait for a determined time interval, before accessing the primary channel.

In a further implementation form of the first aspect, the device is further configured to, if a duration of a transmission by the other device on the primary channel is smaller than a predefined threshold, do not resolve back-off counting for the secondary channel.

In particular, the device may stay operating on the primary channel.

In a further implementation form of the first aspect, the device is further configured to include a Network Allocation Vector, NAV, value to a data packet transmitted on the secondary channel, wherein the NAV value is smaller than or equal to duration of a single data packet.

For example, in some embodiments, the NAV period may be a time period set by the device to prevent other devices to transmit during this period. The NAV value may be announced within the data packet.

Moreover, in some embodiments, the NAV announcement may be missed or it may not be received due to operation on the secondary channel. Thus, in order to prevent these issues the following two main rules may be applied:.

In a further implementation form of the first aspect, the device is further configured to transmit control information and/or management information, using only the primary channel.

A second aspect of the invention provides a system comprising; a first device according to the first aspect or one of the implementation form of the first aspect; and a second device according to the first aspect or one of the implementation form of the first aspect.

A third aspect of the invention provides a method performed by a device for a wireless network comprising a single primary channel having a first predefined bandwidth configured as a common channel of operation for one or more devices associated with a specific access point, and a plurality of secondary channels having a second predefined bandwidth within the first predefined bandwidth, wherein the method comprises executing a first Carrier-Sense Multiple Access with Collision Avoidance, CSMA/CA, instance associated with the primary channel to gain access to the primary channel, wherein a first back-off is generated; and executing a second CSMA/CA instance associated with one of the secondary channels to gain access to the secondary channel, wherein a second back-off is generated.

In an implementation form of the third aspect, the method further comprises executing a plurality of second CSMA/CA instances, each CSMA/CA instance being associated with a different secondary channel and a different maximum bandwidth.

In a further implementation form of the third aspect, the second back-off is decreased only when the secondary channel is free and the primary channel is occupied by another device.

In a further implementation form of the third aspect, the method further comprises, if any back-off reaches zero, transmitting data on the bandwidth defined for a determined channel, for which the back-off was generated.

In a further implementation form of the third aspect, the method further comprises, if the primary channel is occupied by the other device and the second back-off reaches zero, transmitting data on the secondary channel.

In a further implementation form of the third aspect, the method further comprises, if the primary channel become IDLE, refraining execution of at least one operation being currently performed.

The method further comprises, if the primary channel is occupied by another device being associated with another access point, determining the duration of a transmission by the other device on the primary channel.

The method further comprises adjusting total duration of all transmissions on the secondary channel to be shorter than or equal to the duration of the transmission by the other device on the primary channel.

In a further implementation form of the third aspect, the method further comprises when ending a transmission on the secondary channel, waiting for a determined time interval, before accessing the primary channel.

In a further implementation form of the third aspect, the method further comprises, if a duration of a transmission by the other device on the primary channel is smaller than a predefined threshold, do not resolving back-off counting for the secondary channel.

In a further implementation form of the third aspect, the method further comprises including a Network Allocation Vector, NAV, value to a data packet transmitted on the secondary channel, wherein the NAV value is smaller than or equal to duration of a single data packet.

In a further implementation form of the third aspect, the method further comprises transmitting control information and/or management information, using only the primary channel.

<FIG> is a schematic view of a device <NUM> for a wireless network <NUM> comprising a single primary channel <NUM> having a first predefined bandwidth BW-<NUM> configured as a common channel of operation for one or more devices <NUM>, <NUM> associated with a specific access point <NUM>, and a plurality of secondary channels <NUM>, <NUM>, <NUM> having a second predefined bandwidth within the first predefined bandwidth BW-<NUM>, according to an embodiment of the present invention.

The device <NUM> is configured to execute a first Carrier-Sense Multiple Access with Collision Avoidance, CSMA/CA, instance associated with the primary channel <NUM> to gain access to the primary channel <NUM>, wherein a first back-off is generated.

The device <NUM> is further configured to execute a second CSMA/CA instance associated with one of the secondary channels <NUM>, <NUM>, <NUM> to gain access to the secondary channel <NUM>, <NUM>, <NUM>, wherein a second back-off is generated.

The device <NUM> may comprise a circuitry (not shown in <FIG>), the circuitry may comprise hardware and software. The hardware may comprise analog or digital circuitry, or both analog and digital circuitry. In some embodiments, the circuitry comprises one or more processors and a non-volatile memory connected to the one or more processors. The non-volatile memory may carry executable program code which, when executed by the one or more processors, causes the device to perform the operations or methods described herein.

Reference is made to <FIG> which is a schematic view of a system, according to an embodiment of the present invention.

Without limiting the present disclosure, it is assumed that the device <NUM> of the <FIG> is incorporated in the system <NUM> (e.g., as the first device and/or the second device). The system <NUM> comprises a first device <NUM>. The system <NUM> further comprises a second device <NUM>.

The system <NUM> may be for the wireless network <NUM> comprising the single primary channel <NUM> having the first predefined bandwidth BW-<NUM> configured as a common channel of operation (e.g., for the first device <NUM> and the second device <NUM> of the system <NUM>), and a plurality of secondary channels <NUM>, <NUM>, <NUM> having a second predefined bandwidth within the first predefined bandwidth BW-<NUM>.

The first device <NUM> and/or the second device <NUM> of the system <NUM> may execute a first Carrier-Sense Multiple Access with Collision Avoidance, CSMA/CA, instance associated with the primary channel <NUM> to gain access to the primary channel <NUM>, wherein a first back-off is generated; and execute a second CSMA/CA instance associated with one of the secondary channels <NUM>, <NUM>, <NUM> to gain access to the secondary channel <NUM>, <NUM>, <NUM>, wherein a second back-off is generated.

Reference is made to <FIG> which is another exemplary schematic view of the device <NUM> supporting latency sensitive transmission, according to an embodiment of the present invention.

The device <NUM> may support latency-sensitive transmission. For example, the device <NUM> may operate in terms of channel access as a combination multiple devices <NUM>, <NUM>, <NUM>, and may allow more efficient operation within the BW defined by the single primary channel.

Reference is made to <FIG> which is schematic view of the single primary channel <NUM> having a first predefined bandwidth <NUM> and the plurality of secondary channels <NUM>, <NUM>, <NUM> having a second predefined bandwidth within the first predefined bandwidth <NUM>.

In the embodiment of <FIG>, one (a single) primary channel <NUM> is maintained (e.g., by the device <NUM> for the wireless network <NUM>) for transmitting control information and/or management information.

Moreover, the solution may be kept transparent to other devices (e.g., not latency sensitive). Furthermore, the plurality of secondary channels <NUM>, <NUM>, <NUM> may be used for parallel CSMA mechanism which may be defined by the AP <NUM> (not shown in <FIG>) and may further be indicated in advance. The parallel CSMA/CA instances may have two main rules as follow:.

For example, the device <NUM> may execute the parallel CSMA/CA instances considering the above mentioned two main rules.

Reference is made to <FIG> which is a schematic view of back-off counting rules.

The back-off rules counting may be performed, for example, by the device <NUM>.

As discussed, in some embodiments there may be multiple CSMA/CA instances. Moreover, the number of CSMA/CA instances and the exact BW of each instance should be defined within each wireless network <NUM> and may further be announced by the access point <NUM>.

In addition, all of the devices (e.g., device <NUM>, device <NUM>, etc.) that support the suggested method should manage multiple CSMA/CA instances based on the following rules:.

Reference is made to <FIG> which is a schematic view of executing two CSMA/CA instances by the device <NUM>, when having three different phases of operation.

In <FIG>, it is assumed that there are two CSMA/CA instances when having three different phases including phase (<NUM>), phase (<NUM>), and phase (<NUM>), while during all the phases the device <NUM> applies the rules defined above.

Reference is made to <FIG> which is a schematic view of adjusting the duration time. For example, the device <NUM> may adjust the duration time.

In order to make sure that (e.g., the device <NUM> and/or the method performed by the device <NUM>) efficiently reduce the latency, but do not change behavior of the wireless network for devices that do not support the performed method, herein a number of application rules are added.

For example, a duration of transmission may be limited on the plurality of secondary channels <NUM>, <NUM>, <NUM>. For example, it may be assumed that the primary channel <NUM> is occupied by the neighbor network (OBSS), thus, no transmissions within our BSS (related to the device <NUM>) will be initialized during the occupied period.

Thus, in order to prevent any undesired issue, the duration of the transmission may be restricted (e.g., adjusted) on the secondary channel to be less than or equal to the duration of the OBSS signal on the primary channel <NUM>. This implies that the devices that support this method may successfully detect a preamble of the OBSS signal.

Reference is made to <FIG> which is a schematic view of applying a waiting period after transmission on the secondary channel. For example, the device <NUM> may apply the waiting period.

Generally, hidden nodes are a common problem in the WiFi networks. It causes a scenario where different devices face different status of the channel. For instance, some devices may see no signal on the primary channel <NUM> and may try to transmit during the period of the OBSS signal. Moreover, any device that is transmitting during this period on a secondary channel <NUM>, <NUM>, <NUM> cannot be aware of what happened on the primary channel <NUM>. Thus, when the transmission on a determined secondary channel <NUM>, <NUM>, <NUM> is finished, a special waiting period may be defined, e.g., before any action on the primary channel <NUM> can be taken. The waiting period may be relevant only for those devices that were operating on the secondary channel <NUM>, <NUM>, <NUM> during the OBSS transmission. In <FIG>, ay exemplarily waiting period is denoted period as TWAIT.

<FIG> shows a method <NUM> performed by the device <NUM> for a wireless network <NUM> comprising a single primary channel <NUM> having a first predefined bandwidth BW-<NUM> configured as a common channel of operation for one or more devices <NUM>, <NUM> associated with a specific access point <NUM>, and a plurality of secondary channels <NUM>, <NUM>, <NUM> having a second predefined bandwidth within the first predefined bandwidth BW-<NUM>, according to an embodiment of the invention. The method <NUM> may be carried out by the device <NUM>, as is described above.

The method <NUM> comprises a step <NUM> of executing a first Carrier-Sense Multiple Access with Collision Avoidance, CSMA/CA, instance associated with the primary channel <NUM> to gain access to the primary channel <NUM>, wherein a first back-off is generated.

The method <NUM> further comprises a step <NUM> of executing a second CSMA/CA instance associated with one of the secondary channels <NUM>, <NUM>, <NUM> to gain access to the secondary channel <NUM>, <NUM>, <NUM>, wherein a second back-off is generated.

Claim 1:
A device (<NUM>) for a wireless network (<NUM>) comprising a single primary channel (<NUM>) having a first predefined bandwidth (BW-<NUM>) configured as a common channel of operation for one or more devices (<NUM>, <NUM>) associated with a specific access point (<NUM>), and a plurality of secondary channels (<NUM>, <NUM>, <NUM>) having a second predefined bandwidth within the first predefined bandwidth (BW-<NUM>), wherein the device (<NUM>) is configured to:
execute a first Carrier-Sense Multiple Access with Collision Avoidance, CSMA/CA, instance associated with the primary channel (<NUM>) to gain access to the primary channel (<NUM>), wherein a first back-off is generated;
execute a second CSMA/CA instance associated with one of the secondary channels (<NUM>, <NUM>, <NUM>) to gain access to the secondary channel (<NUM>, <NUM>, <NUM>), wherein a second back-off is generated;
if the primary channel (<NUM>) is occupied by another device being associated with another access point, determine duration of a transmission by other device (<NUM>) on the primary channel (<NUM>); and
adjust total duration of all transmissions on the secondary channel (<NUM>, <NUM>, <NUM>) to be shorter than or equal to the duration of the transmission by the other device on the primary channel (<NUM>).