Patent Application
20100085922
The present invention relates to a system and method for improving bandwidth of a broadcasting wireless local area network, and more specifically to providing multiple beacon frames with distinct basic service set identifiers to transmit data for achieving higher throughput.
Technological advancements have made wireless communications devices inexpensive and accordingly ubiquitous. With increase in mobile computing devices such as laptops, tablets, personal digital assistants, etc. there has been a continuous demand to connect them wirelessly and efficiently. A Wireless Local Area Network (WLAN) is a computer network that implements the connection of multiple wireless devices.
Wireless devices connect to a wireless access point in order to gain access to a wireless network. The most commonly used wireless network standard is IEEE 802.11. Most of the computing devices used nowadays have built-in wireless capability i.e. the computing devices are capable of connecting to a wireless network. Examples of such computing devices may include mobile devices, such as personal digital assistants, smartphones, music players, media centers and the like. A computing device attempting to transfer data in a wireless network present in its vicinity needs to establish a connection with the network. A preliminary step in establishing connection includes the access point identifying itself by transmitting a service set identifier (SSID) in a broadcast packet. The broadcast packet is received by all the wireless devices present in the network. A computing device can complete the connection establishment process by exchanging information with the wireless access point, such as security information, bandwidth information, wireless network id, network name and the like. Completion of connection establishment with the wireless network takes a certain amount of time, which is bandwidth inefficient.
The IEEE 802.11 standard currently allows connection from a computing device to a single wireless network at a time. Thus, in order to receive data packets in another wireless network collocated with a connected wireless network, the computing device needs to disassociate itself from the connected network and establish a connection with the other wireless network. This is an inefficient method of data communication, especially if the computing device is a mobile computing device. Moreover, if the data transfer required by the mobile computing device is in the form of small data packets, a connection oriented approach necessitates a substantial overhead in the form of time delay due to connection establishment process. Additionally, in the case of multiple computing devices requiring access to a network simultaneously, a connection-oriented approach requires all the computing devices to establish and remain connected with the network, in order to receive data. This causes a reduction in throughput of the data transfer within the network.
Certain applications of currently used mobile devices require the mobile devices to be aware of the capabilities of the infrastructure in its surroundings. An example of such an application may be that the user of a mobile wireless device may require access to internet while being on the move within a certain area. In such an application, the mobile device may go across multiple wireless local area networks and may require uninterrupted internet access.
Consequently, there is a need for a system and method for providing connectionless data transfer to mobile wireless devices. Further, there is need for improving the throughput of data transfer to mobile wireless devices.
A method and system for improving bandwidth of a local area network is provided. In an embodiment of the present invention, the bandwidth of the local area network is improved by increasing the throughput of data transfer in the network.
In various embodiments of the present invention, the method includes splitting user data into multiple data fragments. Further, the method includes creating multiple beacon frames by placing each data fragment in a unique beacon frame. Further, the method includes broadcasting the beacon frames through a wireless medium by an access point of the network.
In an embodiment of the present invention, the beacon frames are received by a wireless client. Thereafter, the wireless client extracts data fragments from each beacon frame and reconstructs the user data from the extracted data fragments by reassembling the data fragments.
In another embodiment of the present invention, the method for increasing the throughput of data transfer in the network includes creating multiple beacon frames by inserting a data fragment in SSID field of the beacon frame and inserting header information in the SSID field to create the beacon frame. Further, each beacon frame is broadcasted by using a distinct BSSID for each individual frame.
In yet another embodiment of the present invention, upon receipt of a beacon frame by the wireless client, the beacon frame is relayed by a NIC of the wireless client to MAC layer for processing.
In yet another embodiment of the present invention, the system for increasing the throughput of data transfer in the network includes a broadcast server configured to broadcast user data though a wireless medium. Further, the broadcast server comprises a server application configured to fragment user data into multiple data fragments and inserting the data fragments into multiple beacon frames.
In yet another embodiment of the present invention, the system includes a throughput scaling module configured to assign a distinct BSSID to each beacon frame for transmission. Further, the system includes a wireless client configured to receive data broadcasted by the broadcast server.
In yet another embodiment of the present invention, the wireless client of the system includes a WLAN hardware interface configured to drive the one or more beacon frames to MAC layer for further processing. Further, the wireless client includes a data reassemble module configured to extract the one or more data fragments from the one or more beacon frames and to reassemble user data from the one or more data fragments. The wireless client in conclusion utilizes the user data to perform a software task.
The present invention is described by way of embodiments illustrated in the accompanying drawings wherein:
A system and method for increasing throughput of a wireless local area network are described herein. The invention provides transmission of multiple beacon frames, each beacon frame having a different Basic Service Set Identifier (BSSID). The use of a different BSSID with each beacon frame results in higher throughput. Further, the invention provides for connectionless data transmission. This is achieved by fragmenting user data, embedding each data fragment in the SSID field of a beacon frame and then broadcasting the beacon frame.
The following disclosure is provided in order to enable a person having ordinary skill in the art to practice the invention. Exemplary embodiments are provided only for illustrative purposes and various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
The present invention would now be discussed in context of embodiments as illustrated in the accompanying drawings.
The broadcast server 102 broadcasts data over the wireless medium 104. In an embodiment of the present invention, the data broadcasted by the broadcast server 102 is received by wireless clients within transmission range of the broadcast server 102. In an embodiment of the present invention, the wireless client 106 is a mobile computing device requiring the information and use of capabilities of infrastructure in its surroundings. An example of the wireless client 106 includes a mobile computing device used by a user wanting to send email using a wireless connection within the premises of an airport, while waiting for his connecting flight. In an embodiment of the present invention, in order to use a wireless connection for sending email, the wireless client receives data broadcasted by the broadcast server 102 without establishing a connection with the wireless network 100. Broadcasting data includes transmitting a broadcast packet to wireless devices within range of the broadcast server in the network 100. In various embodiments of the present invention, data to be transmitted by a wireless LAN is broken down into smaller data units i.e. data frames and embedded in multiple beacon frames before transmitting it through the wireless medium 104. Beacon frames are part of the IEEE 802.11 wireless network protocol having control information and are transmitted periodically by wireless access points to enable nearby wireless clients to identify and associate with wireless LAN's. Beacon frames generally include information regarding WLAN service area, access point address, time stamps and supported data transfer rates. Additionally, beacon frames also contain information about transmitter's capability, network id, network name etc. which the receiver may use for connection establishment. One of the fields included in a beacon frame is the SSID field used for identifying a specific wireless LAN.
In various embodiments of the present invention, each frame which is to be transmitted is inserted into the SSID field of a beacon frame. The SSID field is a user defined namespace and may be programmed as per requirements. By embedding information in the SSID field, a seamless and connectionless short data stream between the broadcast server 102 and the wireless client 106 may be established.
The wireless client 106 is a computing device capable of wireless communication. The wireless client 106 acts as a receiver and accepts data broadcasted by the broadcast server 102 over the wireless medium 104. In an example, the wireless client 106 scans each available frequency channel for a specified period of time in order to discover existing WLAN networks in its vicinity. In another example, the wireless client 106 sends probe requests for discovering the networks. The wireless client 106 receives beacon frames from all broadcast servers within range, advertising their SSID. In various embodiments of the present invention, when a beacon frame is received by a Network Interface Card (NIC) of the wireless client 106, the SSID field is processed. The wireless client 106 reassembles data frames obtained from the SSID field of each beacon frame in order to obtain the data broadcasted by the broadcast server 102.
The server application 108 comprises two functional modules. The first functional module of the server application 108 fragments user data to be transmitted by the broadcast server 102 into small data packets (frames). In various embodiments of the present invention, a frame comprises header data and payload i.e. user data. In an embodiment of the present invention, the user data may be data required by the wireless client 106 in order to use the infrastructure capabilities available in its vicinity. For example, in case of internet access application, the user data may include HTML and XML files for rendering display of web pages on the wireless client 106. In another example, the user data may include files described in other markup languages, such as, XML, SGML and the like. After fragmenting the user data into frames, the first functional module appends header information to each frame. The header information contains fragment number and file size. The fragment number indicates the ordered position of the fragment in the data reassembled at the client side by collocating the frames received by the wireless client 106. Additionally, the header information includes source address and checksum characters for error detection and correction. The second functional module of the server application 108 includes a scheduler which schedules transmission of header appended frames to the WLAN device driver 112 in a predetermined order from where they are broadcasted as part of beacon frames.
By default, one of the fields in a beacon frame sent by the broadcast server 102 is Basic Service Set Identifier (BSSID). A BSSID field in a beacon frame identifies the Medium Access Control (MAC) address of access point of a wireless LAN. In an embodiment of the present invention, the BSSID field identifies the MAC address of the broadcast server 102. Standard implementations of NIC of wireless devices used in the industry only push beacon frames with unique BSSIDs to the MAC layer for further processing. The throughput scaling module 110 provides means for broadcasting beacon frames including user data with distinct BSSIDs so that all beacon frames sent by the broadcast server 102 are relayed by a NIC of the wireless client 106 to the MAC layer for further processing. The WLAN device driver 112 is a software program that enables communication of the server application 108 with the NIC for appropriate implementation of the 802.11 protocol in transmitting and receiving data frames. The WLAN hardware interface 114, an 802.11 compliant hardware device also known as the Network Interface card (NIC). The WLAN hardware interface 114 is a physical and data link layer device that provides the broadcast server 102 with physical access to the wireless medium 104, for transmitting data and also implements the management of MAC addresses.
The client application 116 is a software application that uses data transmitted by the broadcast server 102 in order to process a software task. In an embodiment of the present invention, the client application 116 may provide a graphical user interface or character user interface, depending upon the kind of device, to view data received from the broadcast server 102. The client application 116 belongs to the application layer of the Open Systems Interconnection (OSI) reference model and directly interacts with the user of a device running the application. The client application 116 receives assembled data packets from the Data Reassemble Module 118, which is responsible for reconstructing data from the frames sent by the broadcast server through the wireless medium 104. In an embodiment of the present invention, the DRM 118 uses the header information (i.e. the fragment number and the file size) in order to reassemble the frames. The WLAN device driver 120 is a software program that enables communication of the client application 116 with a NIC of the wireless client 106. In an embodiment of the present invention, the WLAN Hardware Interface 122 is the NIC that communicates with the wireless medium 104 through microwaves. The WLAN device driver 120 issues commands to the WLAN Hardware interface to enter into scanning stage and capture data. The WLAN device driver 120 also controls the 802.11 protocol implementation with respect to capturing data through the wireless medium 104.
The sequence 410 indicates the series of beacon frames transmitted by the broadcast server 102 in four different frequency channels F1, F2, F3 and F4. The first set 402 of the sequence 410 are the beacon frames captured by the wireless client during its dwell time at F1 frequency. As shown in the figure, the beacon frames captured at F1 frequency are sent with the BSSIDs 1,2,3 and 4. The second set 404 denotes the frames which have been sent at F2 frequency. The third set 406 denotes those frames which have been captured while they were transmitted in F3 frequency. The fourth set 408 denotes those frames which have been missed out while they were transmitted in F4 frequency. All the set of frames when combined together form a fragment fresh interval 410 which represents the duration after which the set of beacon frames are refreshed.
In various embodiments of the present invention, the maximum number of beacons pushed to the wireless client 106 per scan time equals the number of beacons with different BSSIDs i.e. B frames per Tscan time interval. Thus the maximum effective throughput that may be achieved is (B*p*8)/(1000*Tscan) kbps where p is payload per beacon frame.
Throughput=(B*p*8)/max(Tscan;Tfrag)bps
Where B is the number of beacon frames with different BSSID's used, p is payload per beacon frame, Tscan is the scan time, and Tfrag is fragment refresh rate.
At step 604, a scheduler within the broadcast server issues a request command to the server application for a new beacon frame to be broadcasted over a WLAN. In an embodiment of the present invention, a new request command is issued to the server application within predetermined intervals of time. In an example, the predetermined interval is of the order of 500 milliseconds.
At step 606, the server application receives the request and pushes the data packet sequentially based on their fragment number to the scheduler. At step 608, the scheduler relays the data packet to a device driver in a predetermined order where it is inserted in a beacon frame having a unique BSSID.
At step 610, a wireless LAN hardware interface i.e Network Interface Card (NIC) broadcasts the beacon frame containing the data packet. In an embodiment of the present invention, beacon frames containing data packets are transmitted by the NIC at periodic intervals. An example of a periodic interval may be 20 milliseconds. In another embodiment, 802.11 standards specify the use of multiple frequency bands for data transmission. Thus, the beacon frames from the broadcast server are broadcasted at a fixed frequency and may be received only on the same frequency.
At step 704, DRM issues scan command to a WLAN device driver after data request from application and waits for the driver response. In various embodiments of the present invention, the client device initiates periodic scans to discover new networks and during this process it spends a predetermined amount of time (dwell time) in each frequency band. In an example, if 4 frequency channels are in use, a client device will not be able to capture more than ¼ of the beacon frames that were transmitted during the scan time. Therefore, in various embodiments of the present invention, it is ensured by a server application that successive beacon frames should have different BSSIDs which are chosen from a predefined set.
At step 706, the wireless LAN device driver directs a WLAN hardware interface to enter into scanning state and search for frames in the medium. In an embodiment of the present invention, the WLAN hardware interface is a Network Interface Card (NIC). At step 708, the WLAN interface captures the beacon frames broadcasted by a broadcast server. The WLAN interface conforms to the IEEE 802.11 MAC protocol for medium sharing, addressing, and error detection. It corresponds to the ISO Network Model's level 2 Data Link layer. The SSID field of each beacon frame carries user data and since distinct BSSIDs are associated with each beacon frame, throughput of the system is increased. In various embodiments of the present invention, a beacon frame captured is pushed to the DRM.
At step 710, the DRM reassembles data from the received beacon frames based on fragment number and reconstructs complete user data. At step 712, the client application renders the reconstructed data on the wireless client.
The present invention may be implemented in numerous ways including as a system, a method, or a computer readable medium such as a computer readable storage medium or a computer network wherein programming instructions are communicated from a remote location.
The system, method and computer program product for improving bandwidth as described herein is particularly well suited for broadcast systems, however, may be applied to various systems in other domains by performing minor modifications as would be apparent to a person of skill in the art.
While the exemplary embodiments of the present invention are described and illustrated herein, it will be appreciated that they are merely illustrative. It will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from or offending the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 970/CHE/2008 | Apr 2008 | IN | national |
