阅读说明：本技术 站点和运行站点的方法 (Station and method for operating a station ) 是由 希米·西隆 阿维·韦茨曼 多伦·埃兹里 阮卫 孙福清 樊荣虎 于 2014-03-24 设计创作，主要内容包括：描述了一种站点和运行所述站点的方法。所述站点包括：接收器,用于接收通过无线信道发送的无线信号；空闲信道评估,CCA,检测器,用于基于CCA阈值检测所述无线信道是否繁忙；控制器,用于当所述无线信道繁忙,以及通过所述无线信道接收的所述信号并不是针对所述站点时,调高所述CCA检测器的CCA阈值,并降低所述发送器的发送功率。(A station and a method of operating the station are described. The station includes: a receiver for receiving a wireless signal transmitted through a wireless channel; a clear channel assessment, CCA, detector to detect whether the wireless channel is busy based on a CCA threshold; a controller for increasing a CCA threshold of the CCA detector and reducing a transmission power of the transmitter when the wireless channel is busy and the signal received through the wireless channel is not directed to the station.)

1. A station (100, 501-2, 701-1, or 1000) comprising:

a transmitter (1004);

a receiver (101 or 1001) for receiving a wireless signal transmitted through a wireless channel;

a clear channel assessment, CCA, detector (103 or 1003) to detect whether the wireless channel is busy based on a CCA threshold;

a controller (105 or 1005) for increasing a CCA threshold of the CCA detector (103 or 1003) and decreasing a transmission power of the transmitter when the wireless channel is busy and the signal received over the wireless channel is not intended for the station (100, 501-2, 701-1 or 1000).

2. The station (100, 501-2, 701-1 or 1000) according to claim 1,

wherein the CCA detector (103 or 1003) is configured to determine an interference value representing a signal strength of interference in the environment of the station (100, 501-2, 701-1 or 1000), and to determine that the wireless channel is busy when the interference value exceeds the CCA threshold;

the controller (105 or 1005) is configured to adjust the CCA threshold such that the determined interference value is below the CCA threshold after adjusting the CCA threshold.

3. The station (100, 501-2, 701-1 or 1000) according to claim 1,

wherein the transmitter (1004) is configured to transmit a transmit power adjustment signal to at least one other station in accordance with the determined interference value, the transmit power adjustment signal requesting the other station to adjust a transmit power of the other station based on the transmit power adjustment signal.

4. The station (100, 501-2, 701-1 or 1000) according to claim 3,

wherein the controller (105 or 1005) is configured to reset the transmission power of the transmitter to a predefined value after a predetermined time after adjustment of the transmission power of the transmitter or after a predetermined time after reception of a signal for the station (100, 501-2, 701-1 or 1000).

5. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 4, comprising:

a transmitter (1004) or the transmitter (1004) for transmitting a signal to another station over the wireless channel;

wherein the CCA detector (103 or 1003) is further to detect whether the channel is busy when the signal is to be transmitted and is based on the CCA threshold;

the controller (105 or 1005) is further configured to adjust the CCA threshold when the wireless channel is busy and the signal is to be transmitted;

the CCA detector (103 or 1003) is to re-detect based on the adjusted CCA threshold if the wireless channel is busy;

the transmitter (101 or 1001) is configured to transmit the signal when the wireless channel is not busy.

6. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 5, comprising:

a transmitter (1004) or the transmitter (1004);

the CCA detector (103 or 1003) is configured to determine an interference value representing a signal strength of interference in the site environment, and to determine that the wireless channel is busy when the interference value exceeds the CCA threshold;

the transmitter (1004) is configured to adjust a rate of modulation and coding for a signal transmitted by the transmitter (1004) in accordance with the determined interference value.

7. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 6,

wherein the controller (105 or 1005) is to reset the CCA threshold to a predefined value after a predetermined time after adjustment of the CCA threshold of the transmitter or after a predetermined time after reception of a signal for the station.

8. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 7,

wherein the CCA threshold represents a maximum signal strength of a signal that can be decoded by the station (100, 501-2, 701-1, or 1000) but not transmitted to the station until the wireless channel is detected to be clear;

the CCA detector (103 or 1003) is further configured to detect that the wireless channel is busy based on an additional CCA threshold; wherein the additional CCA threshold represents a maximum signal strength of any signal within the wireless channel until the wireless channel is detected to be clear;

the CCA detector (103 or 1003) is further configured to adjust the additional CCA threshold.

9. The station (100, 501-2, 701-1 or 1000) according to claim 8,

wherein the maximum signal strength represented by the additional CCA threshold is higher than the maximum signal strength represented by the CCA threshold.

10. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 9,

wherein the station (100, 501-2, 701-1 or 1000) is an access point for establishing a wireless network.

11. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 10, wherein the station (100, 501-2, 701-1 or 1000) is configured to operate in a temporary wireless network mode.

12. The station (100, 501-2, 701-1 or 1000) according to any one of claims 1 to 10, wherein the station (100, 501-2, 701-1 or 1000) is configured to operate in an infrastructure type wireless network mode.

13. A method (900) of operating a station (100, 501-2, 701-1, or 1000), the method (900) comprising:

receiving (901) a wireless signal transmitted over a wireless channel;

detecting (902) whether the wireless channel is busy based on a CCA threshold;

-increasing (903) the CCA threshold and decreasing the transmission power of the station when the wireless channel is busy and the signal received over the wireless channel is not intended for the station (100, 501-2, 701-1 or 1000).

Technical Field

The present invention relates to the field of wireless data transmission, and in particular, to a station and a method for operating the station.

Technical Field

In IEEE 802.11 networks, stations use a Clear Channel Assessment (CCA) mechanism to determine whether the Channel is busy during carrier sense multiple access/collision avoidance (CSMA/CA) and backoff. If the channel is deemed busy, the station will stop transmitting any data until the channel is free for a predefined period of time.

The IEEE 802.11 standard supports three basic topologies and two methods of operation. The three basic topologies are: first, Independent Basic Service Set (IBSS) — also known as ad-hoc networks. An IBSS includes several sites that communicate directly with each other on a temporary network and peer-to-peer basis. It therefore comprises a set of stations, wherein the stations communicate with each other without any Access Point (AP) or any connection to a wired network. Second, Basic Service Set (BSS) -consists of at least one AP connected to a wired network infrastructure and a set of stations.

Communications between stations (if available) flow through the AP. Third, Extended Service Set (ESS) -consists of a series of overlapping BSSs (each containing an access point) connected together by a Distributed System (DS). Although the DS may be any type of network, it is typically an ethernet LAN.

The three topologies described above can be divided into two modes of operation: in the first mode: infrastructure mode, where each station is connected to an AP. The combination of an AP and a station (or a group of stations) creates a BSS; and several different APs in combination with their respective stations yield an ESS. In the second mode: temporary mode, in which the stations are directly connected to each other (not through an access point). The set of sites form an IBSS.

The above-mentioned Clear Channel Assessment (CCA) is a mechanism used in 802.11 to detect a busy channel and stop transmission. This principle is known as Carrier Sensing (CS), where each station waits until the channel is free to minimize the number of collisions. The channel may be busy because other 802.11 stations are currently transmitting data. In addition, because 802.11 products operate in the unlicensed band, other technologies may transmit, and the station may need to defer until the channel is free.

CCA mechanisms include two seed mechanisms:

1) detecting valid 802.11 signals above a certain threshold;

2) the energy detection of any signal above a certain threshold is not necessarily an 802.11 signal.

For example, 802.11n defines that the CCA mechanism should mark the channel as "busy" if one of the following conditions is met:

a valid 802.11 signal is detected at a receive level of-82 dBm (or above), with a probability of at least 90% in 4 microseconds (sub scheme 1).

There is any signal that is at least 20dB higher than the minimum modulation and coding rate sensitivity (i.e., -82dBm), i.e., any signal that is higher than-82 +20 to-62 dBm (sub-regime 2).

The first rule means that the receiver must detect a valid 802.11 signal in the legacy preamble (specifically, the legacy short training field, L-STF, 8 microseconds long) with high probability. These rules apply to the 20MHz channel which is the primary channel.

For larger bandwidths, additional rules are defined. The CCA mechanism has also supported 40MHz channels, since 802.11n increases the supported Bandwidth (BW) from 20MHz to 40MHz channels. For a 40MHz channel, a valid signal is detected at a receive level of-79 dBm (or above), with a probability of at least 90% in 4 microseconds.

The 40MHz channel is divided into a primary 20MHz channel and a secondary 20MHz channel, such that legacy stations (only 20MHz supported) are supported; in addition, the 40MHz channel may be split between adjacent access points. The same CCA rules as described above are defined for the primary 20MHz channel. For the secondary 20MHz channel, an energy detection threshold of-62 dBm is defined, but no threshold for valid signals is defined. The 802.11ac standard adds efficient 802.11 signal detection on the secondary channel, as well as fine-tuning of the energy detection level of the secondary channel.

There are two mechanisms to control RX sensitivity: adaptive Noise Immunity (ANI) and Adaptive Interference Immunity (AII). Both mechanisms modify the CCA level. The ANI feature improves network performance in environments with high levels of non-802.11 noise, which is generated from devices such as microwaves, bluetooth headsets, video monitors, and cordless phones.

The AII feature improves network performance in environments with high 802.11 interference. The higher the CCA threshold (i.e., -72dBm, not-82 dBm), the lower the sensitivity of the receiver (and thus the better the interference immunity) and the higher the probability of collision with a hidden node.

In practice, increasing the CCA threshold will exacerbate the hidden node problem because the station's receivers will not detect other stations, but their signal-to-noise-and-interference ratios (SINRs) will be affected by the station's transmissions.

If the first station's CCA mechanism determines that the channel is busy and the first station is to transmit data, the first station will defer the transmission until the channel is clear. This may also occur even if the first station needs to transmit to a nearby (e.g., neighboring) station and such transmissions to the neighboring station do not interfere with the current transmission detected by the CCA mechanism. This problem is exacerbated when operating in BSS mode using RTS/CTS, when both the transmitter and receiver activate Network Allocation Vector (NAV) time periods for all stations that can receive their signals. Thus, if the channel is busy, stations cannot transmit, and overall system throughput does not increase (since only one station can transmit at any given time in a region).

Disclosure of Invention

The present invention aims to provide a concept for increasing throughput in a wireless network.

This object is achieved by the features of the independent claims. The description and drawings make the embodiments easier to understand in conjunction with the independent claims.

In a first aspect, a station is provided, which includes: a receiver for receiving a wireless signal transmitted through a wireless channel; a clear channel assessment, CCA, detector to detect whether the wireless channel is busy based on a CCA threshold; a controller for adjusting a CCA threshold of the CCA detector when the wireless channel is busy and the signal received over the wireless channel is not intended for the station.

As described above, although the channel is considered busy, a station can receive and even decode transmissions from a nearby station when the signal strength of the nearby station is stronger than the signal strength of the currently transmitting station (e.g., causing the channel to be busy and the transmitted signal not intended for the station) by adapting the CCA threshold. Adjustment of the CCA threshold can also result in adjustment of cell size. A higher CCA threshold (at which the channel is considered busy) results in a smaller cell size, while a lower CCA threshold results in a larger cell size. Thus, the adaptation of the CCA threshold and the cell size may be performed dynamically by the controller, e.g., whenever the channel is busy and the signal received by the receiver is not intended for the station. For example, the CCA threshold and cell size may be adjusted on a per-message basis.

In this application it should be understood that a signal received but not intended for the station may be a signal using the same wireless standard as the station, which although not intended for the station, may be decoded by the station. Further, such received signals may also be any interfering signals causing interference in the wireless channel. Thus, such received signals need not be information-carrying data signals.

Therefore, the invention supports dynamic adjustment of cell size and simultaneous transceiving without adding interference to the station. In addition, it enables a station (e.g., an access point or client) to modify its own clear channel assessment mechanism so that the station can receive transmission signals even if the channel is deemed busy.

As described above, the dynamic adjustment means: the adjustment performed on an instantaneous channel sensing basis (i.e. when the received signal is not intended for the station) in each CCA event (CCA indicates "busy") is not the adjustment performed on a long term calculation basis.

For example, if the channel is busy, the station (e.g., in the form of an Access Point (AP)) can increase the CCA threshold so that it only detects transmissions from nearby stations whose signal-to-noise-and-interference ratios (SINRs) are sufficiently high at the AP. In addition, transmissions from these nearby stations do not significantly interfere with stations of neighboring BSSs.

The station may be, for example, an access point or a client. Furthermore, the station can be used to act as an access point in infrastructure mode or any station in ad hoc mode.

The present invention can be used to increase the capacity of multiple APs without increasing (or minimizing) the effect of hidden nodes and the likelihood of hidden node collisions. The invention can also be used to reduce noise and interference in the system while maintaining the same coverage area without reducing the cell size.

The invention increases the capacity of the system without modifying the coverage of the cell and without increasing the number of hidden node collisions. If the CCA mechanism determines that the channel is busy, the station does not wait until the channel is clear to restart the Rx procedure, because the change in received signal power when the channel is busy is taken into account.

In a first possible implementation form of the station according to the first aspect, the CCA detector is configured to determine an interference value representing a signal strength of interference in the station environment, and to determine that the wireless channel is busy when the interference value exceeds the CCA threshold; wherein the controller is configured to adjust the CCA threshold such that the determined interference value is below the CCA threshold after adjusting the CCA threshold.

By adjusting the CCA threshold, the determined interference value is below the CCA threshold after adjusting the CCA threshold; when the CCA mechanism is invoked again, what may be achieved is: the CCA detector detects that the channel is clear and the station does not need to stop transmitting or receiving signals. Thus, the data throughput of the station is increased. The interference value representing the strength of the interference signal in the environment of the station may be, for example, an RSSI value measured by a receiver of the station on a radio channel.

In a second possible implementation form of the station according to the first aspect as such or according to the first possible implementation form of the first aspect, the station further comprises a transmitter, wherein the CCA detector is configured to determine an interference value representing a signal strength of interference in the environment of the station, and to determine that the wireless channel is busy when the interference value exceeds the CCA threshold; wherein the controller is further configured to adjust the transmit power of the transmitter based on the determined interference value.

The interference value may be the same as described in the first implementation.

This allows fine tuning of the CCA threshold in the site environment to a current or given interference value, supporting simultaneous data transmission by multiple sites in non-overlapping channels. This implementation is based on the discovery that in some scenarios, a station can transmit data to nearby stations using low transmit power without increasing interference to other stations (outside the cell) even if the channel is busy.

In a third possible implementation form of the station according to the second implementation form of the first aspect, the transmitter is configured to transmit a transmit power adjustment signal to at least one other station according to the determined interference value, where the transmit power adjustment signal requires the other station to adjust a transmit power of the other station based on the transmit power adjustment signal. For example, the controller may provide the transmit power adjustment signal based on the determined interference value.

This allows at least one other station to transmit a signal to the station so that the station can decode the signal with minimal impact on other stations.

This implementation also allows the CCA threshold to be adjusted to meet interference conditions in the site environment. If the CCA mechanism determines that the channel is busy (i.e., some other station is transmitting), the station will adjust the CCA to account for the interference condition so that it will be able to decode transmissions from nearby stations and will adjust the TX power of the transmitting station. Furthermore, in addition to adjusting the TX power of nearby clients, the station can also decide the TX power of nearby clients. Thus, transmissions by a station itself and transmissions by other stations in communication with the station interfere less with transmissions outside the station cell than in conventional networks.

In other words, the implementation enables a station to dynamically adjust the transmit power of the station and other stations in communication with the station, thus minimizing collisions between neighboring BSSs (or neighboring temporary networks). The term "other station" may refer to a station within the BSS, ESS, or ad hoc network.

In a fourth possible implementation form of the station according to the third implementation form of the first aspect or the second implementation form of the first aspect, the controller is configured to reset the transmit power of the transmitter to a predefined value after a predetermined time after the transmit power of the transmitter is adjusted or after a predetermined time after a signal for the station is received.

This allows a quick adaptation of the transmission power and increases the overall data throughput of the station.

In a fifth possible implementation form of the station according to the first aspect as such or any of the preceding implementation forms of the first aspect, the station further comprises a transmitter or the transmitter for transmitting a signal to another station over the wireless channel; the CCA detector is further to detect whether the channel is busy when the signal is to be transmitted and is based on the CCA threshold; the controller is further configured to adjust the CCA threshold when the wireless channel is busy and the signal is to be transmitted; the CCA detector is to re-detect based on the adjusted CCA threshold if the wireless channel is busy; the transmitter is configured to transmit the signal when the wireless channel is not busy (based on a detection based on the adjusted CCA threshold).

This concept allows data to be transmitted to other nearby stations despite the channel being considered busy during initial CCA detection. Thus, the throughput of the station is further increased. If the concept is further combined with adaptation of the transmission power, it is also possible to: during the initial CCA detection, transmissions by the station do not interfere with signals that cause the channel to be busy.

In a sixth possible implementation form of the station according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the station further comprises a transmitter or the transmitter, wherein the CCA detector is configured to determine an interference value representing a signal strength of interference in the environment of the station, and to determine that the wireless channel is busy when the interference value exceeds the CCA threshold; the transmitter is configured to adjust a modulation and coding rate for a signal transmitted by the transmitter according to the determined interference value.

This allows the CCA threshold to be specifically adjusted to the interference values present in the site environment.

In a seventh possible implementation form according to the first aspect as such or any of the preceding implementation forms of the first aspect, the controller is configured to reset the CCA threshold to a predefined value after a predetermined time after the adjustment of the CCA threshold or after a predetermined time after receiving a signal for the station.

This allows the CCA threshold to be readjusted, increasing the capacity of the system, without modifying the coverage of the cell and without increasing the number of hidden node collisions.

In an eighth possible implementation form of the station according to the first aspect as such or any of the preceding implementation forms of the first aspect, the CCA threshold represents a maximum signal strength of a signal that can be decoded by the station but not transmitted to the station until the wireless channel is detected to be clear; the CCA detector is further configured to detect that the wireless channel is busy based on an additional CCA threshold; wherein the additional CCA threshold represents a maximum signal strength of any signal within the wireless channel until the wireless channel is detected to be clear; the CCA detector is further to adjust the additional CCA threshold.

This allows for different CCA thresholds to exist, such as a CCA threshold for signals that have the same wireless standard and are not received and/or transmitted by the station, and an additional CCA threshold for any other interfering signals in the wireless channel. Therefore, because there are different CCA thresholds, the throughput of the station and the capacity of the whole system can be further improved.

In a ninth possible implementation form of the station according to the eighth implementation form of the first aspect, the maximum signal strength represented by the additional CCA threshold is higher than the maximum signal strength represented by the CCA threshold.

This allows reducing noise and interference in the system while maintaining the same coverage without reducing cell size.

In a tenth possible implementation form of the station according to the first aspect as such or any of the preceding implementation forms of the first aspect, the station is an access point for establishing a wireless network.

This allows for providing centralized management, greater security, and flexibility.

In an eleventh possible implementation form of the station according to the first aspect as such or any of the preceding implementation forms of the first aspect, the station is configured to operate in a temporary wireless network mode.

This allows for a wireless network that provides decentralization and failsafe.

In a twelfth possible implementation form of the station according to the first aspect as such or according to any of the preceding implementation forms of the first aspect except for the eleventh possible implementation form, the station is configured to operate in a wireless network mode of an infrastructure type.

This allows higher data transfer rates and higher network security to be provided.

In a second aspect, the invention relates to a method of operating a station, the method comprising: a wireless signal transmitted over a wireless channel is received. Further, the method comprises: detecting whether the wireless channel is busy based on a CCA threshold. Further, the method comprises: adjusting the CCA threshold when the wireless channel is busy and a signal received over the wireless channel is not intended for the station.

In a third aspect, the invention relates to a computer program comprising program code for performing the method according to the second aspect when the computer program runs on a computer.

The computer program may be stored in a computer readable medium. The computer readable medium may be a floppy disk, a hard disk, a CD, a DVD, a USB (universal serial bus) memory device, a RAM (random access memory), a ROM (read only memory), and an EPROM (erasable programmable read only memory). The computer readable medium may also be a data communication network, such as the internet, allowing downloading of the program code.

The methods, systems, and devices described herein may be implemented in software in a digital signal processor DSP, microcontroller, or any other end processor, or in hardware circuitry in an application specific integrated circuit ASIC.

The invention can be implemented in digital electronic circuitry, or in computer hardware, firmware, and software, or in combinations of them, as available hardware in conventional mobile devices, or as new hardware specialized for processing the methods described herein.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

Embodiments of the invention will be described in conjunction with the following drawings, in which:

fig. 1a is a schematic diagram of a station according to an embodiment of the present invention;

fig. 1b is a schematic diagram of a station according to an embodiment of the present invention;

fig. 2a is a schematic diagram of an infrastructure-type wireless network provided by an embodiment of the present invention for explaining the present invention;

FIG. 2b is a schematic diagram of an infrastructure type wireless network used to explain the present invention;

FIG. 3a is a schematic diagram of an infrastructure type wireless network for explaining the present invention;

FIG. 3b is a schematic diagram of an infrastructure type wireless network for explaining the present invention;

fig. 4a is a flowchart of a method for operating the station according to an embodiment of the present invention;

fig. 4b is a flowchart of a method for operating the station according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a wireless network including stations according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a wireless network after adjustment of the CCA threshold according to fig. 5;

fig. 7 is a schematic diagram of a wireless network including stations and configured to operate in a temporary wireless network mode according to an embodiment of the present invention;

fig. 8 is a graph comparing the performance of a system using a conventional site with the performance of a system using a site provided by an embodiment of the present invention.

Detailed Description

The drawings are for the purpose of general description. In different figures, similar or identical elements or steps are numbered the same.

The following detailed description is merely exemplary in nature and is not intended to limit the application and uses.

Furthermore, there is no intention to be bound by any theory presented in the preceding background, summary or the following detailed description.

Fig. 1a is a schematic diagram of a station 100 according to an embodiment of the present invention.

The station 100 may include a receiver 101, a clear channel assessment CCA detector 103, and a controller 105 according to an embodiment of the present invention.

The receiver 101 is operable to receive a wireless signal 107 transmitted over a wireless channel.

The CCA detector 103 may be configured to detect whether the wireless channel is busy based on a CCA threshold.

The controller 105 may be configured to adjust the CCA threshold of the CCA detector 103 when the wireless channel is busy and the signal 107 received over the wireless channel is not intended for the station 100.

As described above, dynamically (e.g., in response to receiving a signal that is not intended for the station 100, and when the channel is busy) adjusting the CCA threshold may increase the throughput of the station.

Fig. 1b is a schematic diagram of a station 1000 according to another embodiment of the present invention.

The station 1000 may include a receiver 1001, a clear channel assessment CCA detector 1003, and a controller 1005, according to an embodiment of the present invention. Further, the station 1000 may include a transmitter 1004. The receiver 1001, the CCA detector 1003, and the controller 1005 may be the same as the receiver 101, the CCA detector 103, and the controller 105 of the station 100, respectively.

The transmitter 1004 may be configured to transmit a transmit power adjustment signal to at least one other station according to the determined interference value, the transmit power adjustment signal requesting the other station to adjust a transmit power of the other station based on the transmit power adjustment signal. The controller 1005 may provide the transmit power adjustment signal to the transmitter 1004 according to the determined interference value. Further, the controller 1005 may be configured to adjust the transmit power of the transmitter 1004 based on the determined interference value.

Fig. 2a is a schematic diagram of an infrastructure type wireless network 200 for explaining the present invention.

Clear Channel Assessment (CCA) is a mechanism used in 802.11 to detect a busy channel and stop transmission. Fig. 2a and 2b depict two cases where for both figures, a circle defines an area where an AP201 (e.g., a station in an embodiment of the present invention) can hear (e.g., successfully detect) transmissions from clients.

Assuming that the CCA threshold is relatively low, when the second client 203b transmits, the AP201 can listen to the second client 203b and stop transmitting, as shown in fig. 2 a.

Assuming that the CCA threshold is relatively high, the AP201 cannot listen to the second client 203b, but the second client 203b can listen to the AP201 (thus the second client 203b becomes a hidden node for the AP 201). When the AP201 is transmitting, it may interfere with the transmission of the second client 203b, as shown in fig. 2 b.

In other words, fig. 2a shows an infrastructure type wireless network 200, said network 200 comprising a first AP201, a first client 203a and a second client 203 b.

The first perception mode 206 defines an area where the first AP201 can hear transmissions from the two clients 203a and 203 b. Thus, when the second client 203b transmits, the first AP201 stops the transmission of the first client 203 a. The perceptual pattern depends on the CCA threshold of the AP 201. As shown in fig. 2a, in the example, the CCA threshold is adjusted to a lower level in the AP201, which results in a larger perception pattern 206 occurring.

The sensing mode refers to an area where a station can hear or sense data (passive) or an area where data can be transmitted (active).

Fig. 2b depicts the same infrastructure type wireless network 200 as shown in fig. 2a, but with the difference that the CCA threshold is adjusted to a higher level in the AP201, which results in a smaller perception pattern 206 occurring.

In contrast to fig. 2a, in fig. 2b, the perceptual pattern 206 is not extended to the second client 203 b. The first AP201 cannot listen to the second client 203b, i.e. the first AP201 does not provide service to the second client 203b, but the second client 203b can hear the first AP201 (therefore, the second client 203b becomes a hidden node of the first AP 201). When the first AP201 is transmitting, the transmission of the second client 203b may be interfered or other transmissions destined for the second client 203b may be interfered.

Fig. 3a is a schematic diagram of an infrastructure type wireless network for explaining the present invention.

The basic Transmitter Power Control (TPC) is part of the 802.11b (frequency hopping spread spectrum) where different tables are defined, allowing the transmit Power to vary according to the total bandwidth of the hopping.

The amendment 802.11h allows the use of the 5GHz U-NII band. The Federal Communications Commission (FCC) regulations exempt the licensed National Information Infrastructure (U-NII) using the 5.25-5.35GHz and 5.47-5.725GHz frequency bands, which require the TPC mechanism to limit the TX power to the Equivalent Isotropic Radiated Power (EIRP) of 24dBm EIRP (or less).

Amendments 802.11e and 802.11z raise TPC and cause the AP to reduce Transmit Power of all stations using Transmit Power Control (TPC) messages (Beacon TPC IE and TPC request).

For example, the AP may inform all stations of the maximum local transmit power, and the stations (supporting 802.11 h) will not transmit at the higher transmit power. Reducing the transmit power of stations will reduce their coverage, which will reduce interference to stations belonging to different BSSs and APs. Fig. 3a and 3b illustrate the case of high and low transmit power and the interference impact of high and low transmit power on neighboring stations, including the AP.

Fig. 3a shows a schematic diagram of a wireless network 300 of the type of infrastructure as an example of high transmission power; each circle represents the coverage area (e.g., RSSI ≧ 82dBm) of one non-AP station (clients numbered 303-1a through 303-3 b).

In fig. 3a, a first client 303-1a and a second client 303-1b communicate with a first access point 301-1, and a third client 303-2a and a fourth client 303-2b communicate with a second access point 301-2. A fifth client 303-3a and a sixth client 303-3b communicate with the third access point 301-3.

The first perception mode 306-1a refers to the perception mode of the first client 303-1 a. Accordingly, the specific perception patterns 306-1b, 306-2a, 306-2b, 306-3a, and 306-3b are also assigned to the other clients 303-1b, 303-2a, 303-2b, 303-3a, and 303-3b, respectively.

Each of the perceptual patterns 306-1a, 306-1b, 306-2a, 306-2b, 306-3a, and 306-3b represents a coverage area of the respective client.

As shown in fig. 3a, both the first client 303-1a and the second client 303-1b may interfere with the transmission signal received by 301-2 of the second access point. Likewise, the third client 303-2a and the fourth client 303-2b may both interfere with the transmission received by the third access point 301-3.

Fig. 3b is a schematic diagram of a further extension of the infrastructure type wireless network 300 of fig. 3a, wherein the client operates at a lower transmit power level than the scenario depicted in fig. 3 a.

The reduced transmit power of the clients 303-1a, 303-1b, 303-2a, 303-2b, 303-3a and 303-3b results in each of the clients 303-1a, 303-1b, 303-2a, 303-2b, 303-3a and 303-3b having a reduced or diminished perception pattern 306-1a, 306-1b, 306-2a, 306-2b, 306-3a and 306-3b, as compared to the scenario depicted in fig. 3 a.

As shown in the figure, by reducing the transmission power of each station, i.e. the transmission power of the clients 303-1a, 303-1b, 303-2a, 303-2b, 303-3a and 303-3b, it can be achieved that each pair of clients, for example, the first client 303-1a and the second client 303-1b form a first pair, the third client 303-2a and the fourth client 303-2b form a second pair, and the fifth client 303-3a and the sixth client 303-3b form a third pair, respectively communicate with the designated AP without interfering with the transmissions of other clients.

For example, the first access point 301-1 is assigned to and communicates with the first pair of clients, the second access point 301-2 is assigned to and communicates with the second pair of clients, and the third access point 301-3 is assigned to and communicates with the third pair of clients.

Each of the clients 303-1a, 303-1b, 303-2a, 303-2b, 303-3a and 303-3b does not interfere with other APs or such interference is at least minimized. For example, the first client 303-1a and the second client 303-1b may not interfere with transmissions of the second access point 301-2 or transmission signals received at the second access point 301-2.

Thus, the first access point 301-1 may operate simultaneously with the second access point 301-2. Also, the third access point 301-3 can operate simultaneously with the second access point 301-2.

Fig. 4a is a block diagram of a method 900 for operating a station (one of the stations 100, 501-2, 701-1, and 1000) according to an embodiment of the present invention.

The method 900 includes a step 901 of receiving a wireless signal transmitted over a wireless channel.

Additionally, the method 900 includes a step 902 of detecting whether the wireless channel is busy based on a CCA threshold.

Additionally, the method 900 includes a step 903 of adjusting the CCA threshold when the wireless channel is busy and a signal received over the wireless channel is not intended for the station 100, 501-2, 701-1, or 1000.

Fig. 4b is a flowchart of a method 400 for operating a station (e.g., station 100) according to an embodiment of the present invention. The method 400 shown in fig. 4b provides an example of an implementation of the method 900 described in fig. 4 a.

The method 400 includes a step 402 of setting a CCA threshold, transmitter power, and transmit power to normal values. Such transmitter power and CCA value settings may be adjusted to prevent excessive unnecessary interference from forming between different wireless networks.

The CCA threshold and the normal value of the transmitter power may be calculated based on conventional ANI and AII, as described in the background section of the invention.

Additionally, the method 400 includes a step 403 of invoking CCA detection by the PHY. For example, CCA detection may be performed by the CCA detector 103 shown in fig. 1a or performed by the CCA detector 1003 described in connection with fig. 1b to detect whether the wireless channel is busy based on a CCA threshold. The physical layer PHY provides an electrical, mechanical and program interface to the transmission medium. The PHY defines the means by which raw bits are sent over the physical link connecting the network nodes instead of logical packets.

For example, the CCA detection may be invoked for a wireless channel based on receiving a signal over the wireless channel.

If it is detected that the channel is not busy or the received signal is intended for the station, conventional signal decoding is performed and/or CCA threshold adaptation is not required (step 404 a).

If, however, the channel is busy and the station is not the destination, i.e. the received signal is not intended for the station (which includes the station not being able to decode the transmission correctly and therefore not knowing whether the station is the destination), step 404b is performed to check whether there is downlink data to be sent.

If the channel is busy and there is no downlink data to send, it is still possible to receive transmissions from nearby stations as long as their transmissions do not interfere with the current transmission detected by the CCA mechanism.

Therefore, the method 400 comprises a step 405a of adjusting the CCA threshold, even if there is no data to be transmitted.

The adjustment of the CCA threshold is performed using the above-described CCA detector 103 or a later-described CCA detector 1003 in conjunction with the above-described controller 105 or a later-described controller 1005.

For example, the CCA detector 103 or 1003 may be configured to determine an interference value, where the interference value represents a signal strength of interference in an environment of a station (e.g., the station 100 or a station 501-2, 701-1, or 1000 described later) performing the method 400. In addition, the CCA detector 103 or 1003 may be configured to determine that the wireless channel is busy when the interference value exceeds the CCA threshold. The controller 105 or 1005 may be configured to adjust the CCA threshold such that the determined interference value is below the CCA threshold after adjusting the CCA threshold.

In other words, once the CCA detector 103 or 1003 detects a busy channel, the controller 105 or 1005 may perceive an interference condition and adjust the CCA threshold accordingly. For example, assume an interference value of-80 dBm (e.g., an RSSI value) and a CCA threshold of-82 dBm would result in a busy channel. The controller 105 or 1005 may adjust the CCA threshold to-70 dBm greater than the interference value. Accordingly, when the CCA is invoked again, the CCA detector 103 or 1003 may conclude that the channel is not busy based on the adjusted CCA threshold.

To ensure that transmissions from nearby stations do not interfere with the current transmission, e.g., transmissions from other stations that are not intended for the station (e.g., a station in the form of an AP), the station can also determine how to modify the nearby station's transmit power, i.e., calculate a new transmit power for the nearby station, by performing step 405b of the method 400. It should be noted that this step is optional and may occur in an infrastructure mode where the station is an AP.

Step 405c is then performed to check whether the interference condition allows transmission to a nearby station.

This checking step 405c can also be performed if the channel is busy and there is downlink data to be sent; i.e. directly after checking if there is downlink data to be transmitted in step 404 b.

In particular, step 405c of checking whether it is appropriate to transmit to a nearby client may be performed as follows:

typically, when the CCA mechanism concludes that the channel is busy, the originating station will stop transmitting until the channel is clear. However, even if the channel is busy, a station 100, 501-2, 701-1 or 1000 may decide that an interference condition allows transmission to a nearby station, i.e. the receiving station will be able to decode the transmission according to the interference condition.

For example, if the standard CCA energy threshold is-82 dBm, the CCA mechanism reports a received interfering signal with an RSSI of-80 dBm, and then a station 100, 501-2, 701-1, or 1000 can determine that when a robust waveform such as a low modulation and coding rate-MCS is used for a transmission to a nearby station, the nearby station can correctly decode the transmission.

Adjusting a CCA level and a transmit power setting of the originating station may be required for transmissions to the nearby station in accordance with the interference condition. As in the typical case, the transmitter may choose to adjust the modulation and coding rate, except for adjusting the transmit power and CCA level.

Specifically, the CCA threshold and the transmit power may be adjusted as follows:

when there is downlink data to be transmitted, if the originating station 100, 501-2, 701-1, or 1000 determines that the interference condition allows data to be transmitted to the nearby station 100, 501-2, 701-1, or 1000 (the receiving station will correctly decode the transmission), it will adjust its CCA threshold and transmit power accordingly.

Furthermore, if the originating station is an AP (in infrastructure mode) and if the receiving station is to reply to the transmission (e.g., send an ACK message, since not all transmissions require an immediate ACK response), the originating station (AP) will also modify the transmit power of the nearby stations.

The CCA threshold will be adjusted so that the CCA mechanism that invokes the threshold adjustment does not result in the channel being busy. Accordingly, the transmit power is adjusted so that the intended receiving station can decode the transmission with minimal interference to stations and APs in neighboring BSSs.

The CCA mechanism can be invoked again in accordance with the adjustment, and the originating station can begin transmitting if the CCA mechanism results in a channel clear. Once the transmission is over, the transmitting station switches to receive mode (i.e., waits for a response message), and after a timeout period for receive mode to take effect, the CCA threshold and the transmit power will return to "normal" values.

If the originating station is an AP (in infrastructure mode) and if the originating station has modified the transmit power settings of the nearby stations, after the timeout period, the originating station will resume the transmit power settings of the nearby stations to normal values (via a new TPC message).

When no downlink data is to be sent:

in this case, the AP needs to modify its CCA, and its transmit power and nearby stations. Therefore, the AP needs to transmit the modified transmission power to the nearby station. If the AP determines that the interference condition allows it to transmit data to a nearby station (so that the nearby station will correctly decode the transmission), the AP will adjust its CCA threshold and transmit power accordingly.

The CCA threshold will be adjusted so that the CCA mechanism that invokes the threshold adjustment does not result in the channel being busy. Accordingly, the transmit power of the AP is adjusted so that the intended receiving station can decode the transmission with minimal interference to stations and APs in neighboring BSSs.

The CCA mechanism can be invoked again in accordance with the adjustment, and the AP can begin transmitting if the CCA mechanism results in a channel clear. The AP will then transmit the modified transmit power adjustment signal value to the nearby station. Once the transmission of the modified transmit power ends, the AP switches to a receive mode, waiting for transmissions from the nearby station.

After a timeout period for the reception mode to take effect (which may depend on the duration of the interfering signal, the AP's decision, etc.), the CCA threshold and the transmit power of the AP and nearby stations may return to "normal" values (for nearby stations, the AP may transmit a new TPC message).

If the channel is still busy after modifying the CCA and invoking the modified CCA, the station should again adjust its CCA and optionally adjust its transmit power as well as the transmit power of nearby stations.

According to an embodiment of the invention, if the interference condition allows transmissions to nearby stations, the CCA threshold is adjusted, the transmit power of at least one originating station is adjusted, and the transmit power of nearby stations is selectively determined, in an adjustment step 406, as described in an extension of method 400.

For example, the maximum transmit power is reduced so that nearby BSSs do not receive the transmission. In some cases, the AP may decide not to modify the transmit power of nearby stations.

Then in a next step 407, the CCA detector of the CCA threshold modification is invoked.

If the channel is busy, the method will start over from step 404 b.

If the channel is not busy, step 408 may be performed to transmit to a nearby client in order to notify the nearby station of the modification of transmit power. Additionally, optionally, step 408 may be performed to transmit data to nearby clients.

To adjust the transmission power of the nearby station, the AP may transmit a TPC message (transmission power adjustment signal) to the nearby station; prior to sending the TPC message, the AP may ensure that the sending of the TPC message does not interfere with the current transmission of one or more neighboring BSSs.

For example, the transmitter of station 100, 501-2, 701-1 or 1000 can be configured to transmit a transmit power adjustment signal to at least one other station based on the determined interference value, the transmit power adjustment signal requiring the other station to adjust the transmit power of the other station based on the transmit power adjustment signal.

To ensure that this is possible, the AP can, for example, assess the path loss between stations in neighboring BSSs and itself and reduce its transmit power so that stations in the neighboring BSSs do not receive AP signals above their respective CCA thresholds, and then the AP adjusts its CCA and changes the power of stations in the BSS. This means that in some scenarios the problem of hidden nodes actually improves system performance.

Then in a next step 409, a receiving step is performed. In other words, the station enters a receive mode to wait for transmissions to be received from nearby stations.

Then in a next step 410, a timeout is invoked.

For example, the controller 105 or the controller 1005 may be configured to reset the transmit power of the station transmitter to a predefined (normal) value after a predetermined time after adjustment of the transmit power or after a predetermined time after reception of a signal intended for the station, and also to reset the CCA threshold to a predefined (normal) value.

Fig. 5 and 6 are schematic diagrams of a wireless network 500 including stations according to an embodiment of the present invention. Wireless network 500 includes a first AP 501-1 in communication with a first client 503-1 and a second AP501-2 in communication with a second client 503-2. Not only the APs 501-1 and 501-2 but also the clients 503-1 and 503-2 may also be an implementation of the stations 100, 501-2, 701-1 or 1000. In other words, the APs 501-1 and 501-2 and the clients 503-1 and 503-2 may be used to dynamically adjust their CCA thresholds and selectively adjust their transmit powers.

In addition, the APs 501-1 and 501-2 may be configured to provide transmit power adjustment signals to the clients 503-1 and 503-2. Although all stations in the network 500 may be considered as stations in embodiments of the present invention, it is sufficient to achieve higher throughput if only one of the APs, such as AP501-2, is a station, as compared to a conventional network.

The first AP 501-1 and the AP501-2 can listen to each other's transmissions and the second AP501-2 and the first client 503-1 can listen to each other's transmissions. This is visible in the level of cell 506-2 or in the sensing mode 506-2 of the second AP 501-2.

The second client 503-2 considers the first AP 501-1 and the first client 503-1 as hidden nodes and vice versa. When the first client 503-1 is transmitting to the first AP 501-1, the CCA mechanism in the second AP501-2 listens for the transmission, so the second AP501-2 cannot transmit to the second client 503-2 and cannot receive the transmission from the second client 503-2. Thus, overall system throughput may be limited to a single concurrent transmission.

However, according to the embodiment of the present invention, when the second AP501-2 listens for the transmission from the first client 503-1 to the first AP 501-1, the second AP501-2 adjusts its CCA and the transmit power of the second client 503-2 (e.g., based on the method 400), so that even if the first client 503-1 is transmitting to the first AP 501-1, the second client 503-2 can transmit to the second AP501-2, and the second AP501-2 can decode the transmission from the second client 503-2. Thus, overall throughput is increased compared to conventional systems. By adjusting the CCA threshold of the second AP501-2, it may be achieved that the second AP501-2 is able to receive data transmitted by the second client 503-2.

By adjusting the transmit power of the second AP501-2 itself and the transmit power of the second client 503-2, it can also be achieved that the transmission between the second AP501-2 and the second client 503-2 does not negatively affect the transmission of the first AP 501-1 and the first client 503-1. It can be seen that, in this example, according to the embodiment of the present invention, when only one of the APs is a station, the throughput of the entire system is also increased sufficiently.

Fig. 6 is a schematic diagram of the network 500 after the second AP501-2 adjusts the CCA threshold. It can be clearly seen that the size of the cell 506-2 or the perception pattern 506-2 of the AP501-2 is much smaller compared to fig. 5. Thus, transmissions between the second AP501-2 and the second client 503-2 no longer affect transmissions between the first AP 501-1 and the first client 503-1, and the second AP501-2 does not have to suppress transmissions. Thus, the overall system throughput is doubled compared to conventional systems.

Fig. 7 is a schematic diagram of a wireless network 700 according to an embodiment of the present invention, where the wireless network 700 includes a first station 701-1, a second station 701-2, a third station 701-3, and a fourth station 701-4.

At least the station 701-1 and one of the stations 701-2, 701-3, and 701-4 may be configured to operate in a temporary wireless network mode.

At least the station 701-1 is a station provided in the embodiment of the present invention. The first station 701-1 is configured to adjust its CCA threshold. The first station 701-1 may adjust its CCA threshold such that it is still able to receive signals from the second station 701-2.

In this case, the cell area (represented by the perception pattern 706-1) of the first station 701-1 is sufficiently small in order to communicate with the second station 701-2 and not interfere with other stations. The perception pattern 706-1 represents an area where the first station 701-1 is able to listen to other stations.

Fig. 8 is a graph 800 comparing the performance of a wireless system including stations with the performance of a conventional wireless system in an embodiment of the present invention.

Fig. 8 shows a graph 800 illustrating the increase in throughput for two indoor APs 10m apart when using an embodiment of the present invention. The y-axis of the graph 800 represents the data transmission rate in terms of throughput of one AP, or more precisely, the average throughput of one AP of the two indoor APs, in megabits per second.

In the field of telecommunications, the bit rate or data transmission rate is the average number of bits, characters or blocks transmitted between devices per unit time in a data transmission system. The x-axis of the graph 800 shows the number of clients communicating with the two indoor APs.

The two curves 801 and 803 shown in said fig. 8 represent performance characteristics. A solid line 801 represents throughput of a wireless system using two indoor APs operating in accordance with an embodiment of the present invention and a dashed line 803 represents throughput of a wireless system using a legacy AP not operating in accordance with an embodiment of the present invention. Using embodiments of the present invention, throughput is increased by over 80% over conventional systems, as seen by the solid line 801, and particularly by the comparison of the solid line 801 to the dashed line 803.

From the above description, those skilled in the art can easily understand various methods, systems, computer programs in recording media, and the like provided by the embodiments of the present invention.

The present invention also supports computer program products comprising computer-executable code or computer-executable instructions that, when executed, cause at least one computer to perform the execution and calculation steps described herein.

Many alternatives, modifications, and variations of the present invention will be apparent to those skilled in the art in light of the foregoing description. Of course, those skilled in the art will recognize that the present invention may have numerous applications beyond those described above.

While the invention has been described in connection with one or more specific embodiments, those skilled in the art will recognize that many modifications may be made without departing from the scope of the invention. It is, therefore, to be understood that within the scope of the appended claims and equivalents, the invention may be practiced otherwise than as specifically described.

The word "comprising" in the claims does not exclude other elements or steps than those listed and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several means recited in the claims.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.