Claims:We claim:

A method of optimizing utilization of bandwidth during a wireless communication, the method comprising:
performing by a serving access point, an initial set of communication;
determining by the serving access point, unutilized bandwidth based on the initial set of communication;
identifying by the serving access point, one or more stations for performing the wireless communication using the determined unutilized bandwidth; and
performing by the serving access point, the wireless communication with the identified one or more stations over the determined unutilized bandwidth.

The method as claimed in claim 1, wherein performing by the serving access point, the initial set of communication comprises:
sending one or more request to send (RTS) messages on one or more channels to the one or more stations; and
receiving from the one or more stations, one or more clear to send (CTS) messages on the one or more channels.

The method as claimed in claim 1, wherein determining by the serving access point, unutilized bandwidth based on the initial set of communication comprises:
identifying the one or more channels on which the serving access point fails to receive the CTS messages based on the initial set of communication.

The method as claimed in claim 1, wherein identifying, by the serving access point, one or more stations for performing the wireless communication using the determined bandwidth, comprising:
generating a list of neighboring base stations that are visible to the serving access point;
receiving neighboring base station (N-BSS) information by the serving access point, from the one or more stations;
analyzing the N-BSS information received from the one or more stations; and
identifying based on the analyses of the N-BSS information, the one or more stations whose list of neighboring base stations is same as (or a subset of) the list of neighboring base stations that are visible to the said serving access point for performing the wireless communication using the determined bandwidth.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by the serving access point, an N-BSS neighbor report request message to the one or more stations;
providing by each station of the one or more stations, an N-BSS information to the serving access point regardless of change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by the serving access point, an N-BSS neighbor report request message to the one or more stations;
providing by each station of the one or more stations on receiving the N-BSS neighbor report request message, the N-BSS information to the serving access point when there is a change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
periodically sending by each station of the one or more stations, the N-BSS information to the serving access point regardless of change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
periodically sending by each station of the one or more stations, the N-BSS information to the serving access point when there is a change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by each station of the one or more stations, the N-BSS information to the serving access point on a preconfigured frequency, wherein the preconfigured frequency is based on change in one of a channel condition and station mobility.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by the serving access point, the N-BSS information periodically or on-demand on a pre-defined frame to the one or more stations;
analyzing by each station of the one or more stations, N-BSS information received from the serving access point; and
providing by each station of the one or more stations based on the analysis, to the serving access point on identifying one or more neighboring access point hidden from the serving access point, and change in the N-BSS information from the N-BSS information shared previously.

Dated this the 12th day of January 2016

Signature

KEERTHI J S
Patent agent
Agent for the applicant
, Description:FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; Rule 13)

METHOD OF OPTIMIZING UTILIZATION OF BANDWIDTH DURING A WIRELESS COMMUNICATION

SAMSUNG R&D INSTITUTE INDIA – BANGALORE PRIVATE LIMITED,
#2870, Orion Building, Bagmane Constellation Business Park,
Outer Ring Road, Doddanekundi Circle,
Marathahalli Post, Bangalore – 560037,
Karnataka, India,
an Indian Company

The following Specification particularly describes the invention and the manner in which it is to be performed

FIELD OF THE INVENTION
The present invention generally relates to the field of wireless communication, and more particularly relates to a method for optimizing utilization of bandwidth during a wireless communication and eliminating interference caused by hidden nodes.

BACKGROUND OF THE INVENTION
In the wireless communication networks, network nodes communicate wirelessly with each other over transmission channels. In some wireless communication networks, transmission channels may be shared by network nodes. Various protocols exist to enable communication between network nodes to occur efficiently. The network nodes utilize a Request-to-Send (RTS)/Clear-to-Send (CTS) protocol to reduce interference introduced by a hidden node problem. The protocol allows a transmitter node wishing to send data to initiate the RTS/CTS protocol by transmitting a Request-to-Send (RTS) message and a receiver node replies with a Clear-to-Send (CTS) message. Upon receipt of the CTS message the transmitter node begins transmission, and any other node receiving the CTS message should refrain from sending data for a given time thereby solving the hidden node problem. The amount of time the node should wait before trying to get access to the medium is included in both the RTS message and the CTS message.

Figure 1 is a schematic diagram illustrating a wireless communication network having no interference during RTS/CTS mechanism for dynamic channel operation, according to the existing art. The RTS/CTS mechanism for dynamic channel operation is illustrated as follows. Consider the following continuous channel numbers 36, 40, 44 and 48 on a 5 GHz ISM band.

Suppose an access point (AP1) is operating on a 20 MHz primary channel 36 and has respective secondary channels 40, 44, and 48. Now for an 80 MHz data transmission, RTS is sent on all 20 MHz channels that are 36-48. Destination device (STA3) on receiving the RTS will respond with a CTS message on all the 20 MHz channels that are 36-48 only if it senses the channels to be idle. In the Figure 1, the destination device (STA3) has sent CTS message over all the four channels and is experiencing no interference.

Figure 2 is a schematic diagram illustrating a wireless communication network having interference during the RTS/CTS mechanism for dynamic channel operation, according to the existing art. Consider a scenario where destination devices finds two channels 44 and 48 of 20 MHz are not idle and the other two channels 36 and 40 are idle where the source device had sent the RTS on all the four channels. If the operation mode is dynamic, then the destination device sends CTS messages on 36 and 40 for a 40 MHz transmission clearance but CTS messages would not be sent on channels 44 and 48 which are not idle. Therefore the transmission will be limited to 40 MHz channel operation against the requested 80 MHz bandwidth (RTS), causing an underutilization of bandwidth since the remaining 40 MHz will not be used for any other destination node by the said source node.

The RTS/CTS mechanism has been an effective way to minimize the impact of hidden node problem that causes throughput degradation in IEEE 802.11 families and it is being part of all access standards defined by IEEE 802.11 WG. With the advancement of the standardization work in IEEE 802.11ax, achieving higher throughput in dense deployment scenario is one of the key requirements.

According to IEEE 802.11n and the recent IEEE 802.11ac standard, usage of wider bandwidths i.e. 40 MHz, 80 MHz and 160 MHz transmissions has been one of the ways to achieve higher data rate. There is also an RTS/CTS mechanism adopted in the standard for static or dynamic channel operation to combat multichannel-hidden node problem. However this method is prone to underutilization of the bandwidth in scenarios where the probability of hidden node is prominent.

Hence, there is a need for a method to improve the channel utilization of the wireless network when some of the nodes in the network are experiencing hidden node problem.

SUMMARY OF THE INVENTION
An embodiment of the present invention discloses a method of optimizing utilization of bandwidth during a wireless communication. The method comprises performing by a serving access point, an initial set of communication, determining by the serving access point, unutilized bandwidth based on the initial set of communication, identifying by the serving access point, one or more stations for performing the wireless communication using the determined unutilized bandwidth, and performing by the serving access point, the wireless communication with the identified one or more stations over the determined unutilized bandwidth.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a schematic diagram illustrating no interference with the RTS/CTS mechanism for dynamic channel operation, according to the existing art.

Figure 2 is a schematic diagram illustrating interference with the RTS/CTS mechanism for dynamic channel operation, according to the existing art.

Figure 3 is a schematic diagram illustrating usage of unutilized bandwidth, according to an embodiment of the present invention.

Figure 4 is a schematic diagram illustrating indirect BSS arrangement, according to an embodiment of the present invention.

Figure 5 is a schematic diagram illustrating distribution of 'N’ networks with 'S' stations, according to an embodiment of the present invention.

Figure 6 is a graphical diagram illustrating number of stations vs the number of stations per network, according to an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments. The present invention can be modified in various forms. Thus, the embodiments of the present invention are only provided to explain more clearly the present invention to the ordinarily skilled in the art of the present invention. In the accompanying drawings, like reference numerals are used to indicate like components.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. The term base station and access point are used interchangeably.

According to an embodiment of the present invention, IEEE 802.11ac defines one primary channel of 20 MHz and provides an option to bond with multiple secondary channels to facilitate wider band data transmission. The extended bandwidth is continuous and forms a combination of 40 MHz, 80 MHz and 160 MHz along with primary channel of 20 MHz. Data transmission over wider bandwidths such as 40 MHz, 80 MHz and 160 MHz is operated in static or dynamic channel operation.

Further, to enable such data transmissions over wider bandwidths, an RTS/CTS exchange mechanism is presented. The mechanism involves sending RTS messages after sensing the primary channel idle in DCF (Distributed Coordination Function) Interframe Space (DIFS) period and secondary channels in PCF (Point Coordination Function) Interframe Space (PIFS) period. The destination device responds with CTS messages on 20 MHz channels on which it received the RTS messages, only if it senses the channel around it to be idle.

While operating in static mode the source will initiate data transmission only if it has received CTS from the destination device on all the requested 20 MHz channels. Where as in dynamic channel operation a source will initiate data transmission on the contiguous 20 MHz channels on which it received CTS including the primary channel.

Figure 3 is a schematic diagram illustrating usage of unutilized bandwidth, according to an embodiment of the present invention. According to figure 3, the AP1 transmits RTS over 40MHz of STA3 and over 40MHz of STA2. The STA3 responds with the CTS to the AP1, therefore the AP1 transmits the data over 40MHz of STA3. Whereas the STA2 does not respond with the CTS, hence the 40MHz of STA2 is not utilized.

In order to reduce the underutilization of bandwidth, the selection criteria for the AP are defined. This helps in choosing the most probable candidate station to which an AP successfully transmits the data on the initially rejected bandwidth by the said first STA, that is on which no CTS was received. The candidate station is chosen which does not experience any hidden node problem and a successful data transmission to that station would nullify the underutilization of the bandwidth.

Solution Formulation:
Let the basic service set (BSS) of the serving access point AP_1 contain N stations denoted by the set
S^AP1= {s_1^AP1, s_2^AP1, … s_N^AP1 }

Let the set a_j^AP1={A_1,A_2,…A_Nj} denote the set of N_j APs to whom the station s_j^AP1 is visible. It should be noted here that some of the APs that are a part of the set a_j^AP1 could be hidden from AP_1.

For each station j in S^AP1,a_j^AP1 is partitioned into subsets H_j^AP1?a_j^AP1 and E_j^AP1 ??a?_j^AP1 such that H_j^AP1 represents the set of APs hidden from AP_1 and E_j^AP1 represents the set of APs that are visible to AP_1 and H_j^AP1 ? E_j^AP1=F

Accordingly, for the data transfer to be successful between AP_1 and any of its stations say s_j^AP1, it is necessary that H_j^AP1 is a null set. This is because other APs that are visible to AP_1 will stop their transmission upon hearing the previous unsuccessful RTS transmission from AP_1.

According to an embodiment of the present invention, the MATLAB simulations are used to analyze the relevance of hidden node problem in dense networks. With the help of MATLAB simulations it is shown that, as the network density increases the hidden node problem becomes more prominent. It is noticed that around 68% of stations have hidden nodes which are not visible to its respective AP.

Figure 4 is a schematic diagram illustrating indirect BSS arrangement, according to an embodiment of the present invention. According to the figure 4, there are four access points (AP), and nine stations (STA) connected to the respective access points. The AP1 is connected to STA1, STA2, STA3 and STA4, the AP2 is connected to STA3, STA5 and STA6, the AP3 is connected to STA1, STA2, STA7 and STA8, and the AP4 is connected to STA8 and STA9. Further it is noted that in the above exemplary scenario AP1 and AP3 can directly hear each other’s transmissions. Assume that AP1 initiates first transmission with STA1 by sending RTS ion four channels out of which STA1 sends the CTS only on two channels. In order to utilize the available bandwidth the AP1 can chose any STA connected to it which can hear either only AP1 or can hear both AP1 and AP3. Hence in this exemplary scenario AP1 can choose STA4 as the candidate node for transmission on the unutilized bandwidth. Here, for the AP1, STA2 cannot be chosen as the probable candidate station to utilize the unutilized bandwidth as they are connected to AP4 and it might cause the hidden node problem leading to interference. Similarly with the other stations like STA3 cannot be chosen as the probable candidate station as it is connected to AP2. It is to be noted that AP4 and AP2 are not directly visible to AP1. STA2 indicates to AP1 that AP4 is an indirect overlapping BSS. Therefore, the only suitable candidate station that could be chosen for AP1 to utilize the unutilized bandwidth is STA4 as it is not connected to any of the other APs and is sure to not cause the hidden node problem as in the case of other stations connected to AP1.

An embodiment of the present invention describes an implementation protocol and gathering of neighbor basic service set (BSS) information. Each of the AP/STAs periodically conducts background scanning on all the channels for Neighboring BSS (N-BSS) information. The N-BSS information which includes a BSS ID or a media access control (MAC) address, should be captured. Each of the AP/STAs maintains an N-BSS list ?(a?_j^APi) and this list contains all the neighboring BSS ID/MAC addresses. There is also an indirect BSS which needs to be captured, where each of the AP/STA additionally decodes RTS/CTS messages from neighboring STAs that is not from its own BSS. The decoding is done to identify corresponding MAC address of that neighboring STAs BSS which could be hidden from that AP/STA. Indirect BSS is also part of the N-BSS list.

According to an embodiment of the present invention, N-BSS list procedures provided by either the APs or the STAs are described as follows. When on demand, APs send the N-BSS neighboring report request message to STAs, and each of the STA reports neighboring N-BSS information (a_j^APi) to AP (N-BSS Report). There are two modes to report, which are as follows. In the first mode, each station reports N-BSS list a_j^APi(t), regardless of the STA checking if its N-BSS list has been modified from last report a_j^APi(n-1). Whereas in the second mode, each station reports N-BSS list to its respective AP, only if there is a change in its N-BSS list a_j^APi(t) from last reported N-BSS a_j^APi(n-1).

Further, even when proactive, there are two modes to report which are as follows. In the first mode, each station reports N-BSS list periodically, regardless of the STA checking if the list has been modified from last report. Whereas in the second mode, each station reports N-BSS list to its respective AP, only if there is an update in its N-BSS list. Frequency of a_j^APi information transmitted to AP could be adapted to change in channel, environment or mobility.

According to another embodiment of the present invention, N-BSS list procedures provided by either the APs or the STAs are described as follows. APi broadcasts its own N-BSS list periodically or on-demand on a new frame (Multi-Channel Neighbor Report) and by default all STAs except legacy devices are considered H_j^APi =F. Legacy devices (802.11a, 802.11n) are considered if H_j^APi ?F.

Further, after receiving the report from APi, each station responds with its own N-BSS list (Multi-Channel Neighbor Response) to its corresponding AP, only if H_j^APi ?F , and if there is a change in its N-BSS list a_j^APi(n) from last reported N-BSS a_j^APi(n-1).

Figure 5 is a schematic diagram illustrating distribution of 'N’ networks with 'S' stations, according to an embodiment of the present invention. Here, ‘N’ represents number of networks and ‘S’ represents number of stations. Consider ‘N’ networks that are randomly distributed in an area (X Y) and each network ‘N’ randomly chooses ‘S’ number of stations in the range R {1, S_max}. Consider a desired network is D_n which has an access point (AP1) and 25 stations represented by S_25. These stations are randomly distributed around AP1 and nodes in S_25 are evaluated to find those which satisfy the condition H_s^AP1 is a null set. Simulation results are averaged over multiple runs (100,000) for reliability.

Figure 6 is a graphical diagram illustrating number of stations vs the number of stations per network, according to an embodiment of the present invention. According to the illustration, it is noticed that there are at least 32% of nodes which do not have hidden nodes set matched against its respective access points i.e. H_s^AP1 is a null set. This indicates that an AP is free to send packets to any of the nodes which fall in the 32% of the network without the collisions or without hidden node problem at the destination. Additionally, these nodes in 32% of the network do not need an RTS/CTS mechanism.

Although the invention of the method has been described in connection with the embodiments of the present invention illustrated in the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and changes may be made thereto without departing from the scope and spirit of the invention.

We claim:

A method of optimizing utilization of bandwidth during a wireless communication, the method comprising:
performing by a serving access point, an initial set of communication;
determining by the serving access point, unutilized bandwidth based on the initial set of communication;
identifying by the serving access point, one or more stations for performing the wireless communication using the determined unutilized bandwidth; and
performing by the serving access point, the wireless communication with the identified one or more stations over the determined unutilized bandwidth.

The method as claimed in claim 1, wherein performing by the serving access point, the initial set of communication comprises:
sending one or more request to send (RTS) messages on one or more channels to the one or more stations; and
receiving from the one or more stations, one or more clear to send (CTS) messages on the one or more channels.

The method as claimed in claim 1, wherein determining by the serving access point, unutilized bandwidth based on the initial set of communication comprises:
identifying the one or more channels on which the serving access point fails to receive the CTS messages based on the initial set of communication.

The method as claimed in claim 1, wherein identifying, by the serving access point, one or more stations for performing the wireless communication using the determined bandwidth, comprising:
generating a list of neighboring base stations that are visible to the serving access point;
receiving neighboring base station (N-BSS) information by the serving access point, from the one or more stations;
analyzing the N-BSS information received from the one or more stations; and
identifying based on the analyses of the N-BSS information, the one or more stations whose list of neighboring base stations is same as (or a subset of) the list of neighboring base stations that are visible to the said serving access point for performing the wireless communication using the determined bandwidth.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by the serving access point, an N-BSS neighbor report request message to the one or more stations;
providing by each station of the one or more stations, an N-BSS information to the serving access point regardless of change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by the serving access point, an N-BSS neighbor report request message to the one or more stations;
providing by each station of the one or more stations on receiving the N-BSS neighbor report request message, the N-BSS information to the serving access point when there is a change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
periodically sending by each station of the one or more stations, the N-BSS information to the serving access point regardless of change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
periodically sending by each station of the one or more stations, the N-BSS information to the serving access point when there is a change in the N-BSS information from the N-BSS information shared previously.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by each station of the one or more stations, the N-BSS information to the serving access point on a preconfigured frequency, wherein the preconfigured frequency is based on change in one of a channel condition and station mobility.

The method as claimed in claim 4, wherein the N-BSS information is received by the serving access point from the one or more stations on performing the steps comprises:
sending by the serving access point, the N-BSS information periodically or on-demand on a pre-defined frame to the one or more stations;
analyzing by each station of the one or more stations, N-BSS information received from the serving access point; and
providing by each station of the one or more stations based on the analysis, to the serving access point on identifying one or more neighboring access point hidden from the serving access point, and change in the N-BSS information from the N-BSS information shared previously.

Dated this the 12th day of January 2016

Signature

KEERTHI J S
Patent agent
Agent for the applicant