English:
[0001] Wireless networks may operate on unlicensed bands, such as Wi-Fi. Wireless networks that use unlicensed bands may have lower costs than wireless networks that use licensed bands, such as cellular or WiMax networks. For example, deployment, maintenance and system costs of wireless networks using unlicensed bands may be lower than that of those using licensed bands.
[0002] However, wireless networks that use unlicensed bands and that are relatively large in size, may not operate effectively. For example, information may be lost and/or transmitted repeatedly in such large wireless networks due to contention and interference, as well as a lack of determinism. Manufacturers, vendors, and/or users are challenged to provide more effective methods for transmitting information over large wireless networks using unlicensed bands.
[0004] FIG. 1 is an example block diagram of a wireless network including a plurality of wireless access points (WAP);
[0005] FIG. 2 is an example timing diagram of the WAPs of FIG. 1 ;
[0006] FIG. 3 is an example block diagram of a computing device including instructions for transmitting information over a wireless network; and
[0007] FIG. 4 is an example flowchart of a method for transmitting information over a wireless network.
[0008] Specific details are given in the following description to provide a thorough understanding of embodiments. However, it will be understood by one of ordinary skill in the art that embodiments may be practiced without these specific details. For example, systems may be shown in block diagrams in order not to obscure embodiments in unnecessary detail. In other instances, well-known processes, structures and techniques may be shown without unnecessary detail in order to avoid obscuring embodiments.
[0009] Wireless networks may operate on unlicensed bands and use standards like Wi-Fi, in order to save costs, compared to operating on licensed bands. Also, an bands for licensing and/or exclusive use may not always be available in certain environments. In addition to avoiding licensing fees, wireless networks using unlicensed bands may also have lower deployment, maintenance and system costs.
[0010] Nonetheless, interference may become too great between network elements, such as wireless access points (WAP) or client devices (CD), using a same frequency channel of the unlicensed band in larger wireless networks. For example, a large wireless network, such as an oil and gas exploration system, may include thousands to millions of CDs, such as sensors, that send information to one or more WAPs over the same frequency channel. The one or more WAPs may forward the information to a central entity, such as a central command center. In this case, reliable delivery of the information may be difficult because of the interference between the CDs and or WAPs attempting to communicate simultaneously over the same frequency channel. Further, if the CDs and/or WAPs are running on a limited power source, such as a battery, the power source may become drained more quickly, due to retransmissions of information lost to radio frequency (RF) interference. In addition, time may be wasted attempting to receive and/or transmit the information due to the RF interference.
[0011] Embodiments may allow for large wireless networks using unlicensed bands to operate with reduced RF interference while also conserving more power and reducing times to transmit or receive information. For example, a plurality of WAPs may share a same frequency channel that is part of an industrial, scientific and medical (ISM) radio band. Each of a plurality of CDs may communicate with one of the WAPs along the same frequency channel.
[0013] Thus, by limiting ownership of the single, same frequency channel to one WAP at a time and by scheduling polling of the CDs during a time that an associated WAP is in exclusive control of the same frequency channel, embodiments may provide greater fairness, save power and reduce information reception/transmission times. Moreover, by using the ISM radio band, embodiments may be more readily deployed in different environments, such as different parts over the world, because the costs and restrictions inherent in securing a licensed band may not be present
[0014] Referring to the drawings, FIG. 1 is an example block diagram a wireless network 100 including a plurality of WAPs 110-1 to 110-n and a plurality of client devices 120-1 to 120-n, where n is a natural number. The wireless network 100 may be any type of network using a transmission system including radio waves from an industrial, scientific and medical (ISM) radio band spectrum. The ISM radio band is generally used for unlicensed operations. Thus, the WAPs may, for example, be wireless LAN devices using one of the following frequency channels: 2450 MHz band (Bluetooth), 5800 MHz band (HIPERLAN), 2450 and 5800 MHz bands (IEEE 802.11/WiFi) and or 915 and 2450 MHz bands (IEEE 802.15.4 ZigBee).
[0015] FIG. 1 shows a plurality of WAPs 110-1 to 110-n where at least two of the WAPs are shown to share the same frequency channel A that is part of the ISM band, such as one of the frequency channels listed above. The term frequency channel may refer to a specific, pair and/or band of frequencies. For example, the frequency channel 2.450 Gigahertz (GHz) may refer to a center frequency of 2.450 GHz and a frequency range of 2.400 GHz to 2.500 GHz.
[0016] The WAPs 110-1 to 110-n may be any type of device that allows information collected from the CDs 120-1 to 120-n to be relayed to a remainder of the wireless network 100, such as a router, a switch, a gateway, a server, a command center and the like. The CDs 120-1 to 120-n may include any type of device capable of measuring, collecting, storing and/or transmitting information to one of the WAPs 110-1 to 110-n, such as a sensor, a transmitter, and the like. For example, an embodiment of the wireless network 100 may include about 100 WAPs 110-1 to 110- 100 and about 100 CDs 120 associated each WAP 110. Each WAP 110 and its associated one or more CDs 120 may be referred to as a cell. For example, the first WAP 110-1 and the first devices 120-1 may form a first cell while the nth WAP 110-n and the nth devices 120-n may form an nth cell.
[0017] The WAPs 110-1 to 110-n may include, for example, a hardware device including electronic circuitry for implementing the functionality described below, such as control logic and/or memory. In addition or as an alternative, the WAPs 110-1 to 110-n may be implemented as a series of instructions encoded on a machine- readable storage medium and executable by a processor.
[0019] As shown in FIG. 1, each of the WAPs 110-1 to 110-n transmits a beacon during a beacon transmit period (BTP) on the frequency channel A. The beacon may be a continuous or periodic radio signal with limited information content, such as an SSID, a channel number and security protocols such as WEP (Wired Equivalent Privacy) or WPA (Wi-Fi Protected Access). The beacon may be transmitted at regular intervals by the WAPs 110-1 to 110-n.
[0020] Next, a first WAP 110-1 of the plurality of WAPs 110-1 to 110-n that transmitted the beacons is to collect information from at least one of the plurality of CDs 120-1 associated with the first WAP 110-1 during a control access period (CAP). Lastly, the first WAP 110-1 transmits the collected information during an open access period (OAP). The BTP, CAP and OAP will be described in greater detail with respect to FIG. 2.
[0021] FIG. 2 is an example timing diagram of the WAPs 110 of FIG. 1. While FIG. 2 only shows the timing diagram with respect to two WAPs 110-1 and 110-n, the BTP, CAP and OAP may repeat for each of the WAPs 110-1 to 110-n. A single cycle is completed when all of the WAPs 110-1 to 110-n have received an opportunity to use the frequency channel A. For example, a length of the BTP may be 20 milliseconds (ms), the CAP may be 60 ms and the OAP may be 70 ms. Yet the entire cycle may be 20 seconds. Thus, each of the BTP, CAP and OAP may repeat every 150 ms until all of the WAPs 110-1 to 110-n have received their turn to use the frequency channel A. For instance, if there are 100 WAPs 110-1 to 110-100, it may take 15 seconds (150 ms x 100) for all of the WAPs 110-1 to 110-100 to use the frequency channel A. Thus, the cycle may be 15 seconds or the cycle may remain longer, such as 20 seconds, with a last 5 seconds of cycle being open to other uses of the frequency channel A. Once the cycle ends, a new cycle starts, with each cycle restarting with the first WAP 110-1.
[0022] As shown in FIG. 2, the first WAP 110-1 and the nth WAP 110-n do not transmit the beacon simultaneously or at a same time during the BTP. Instead, each of the WAPs 110-1 to 110-n transmits the beacon sequentially during the BTP so as to avoid or reduce radio frequency interference from beacons of different WAPs 110 colliding. The sequence for transmitting the unmarked beacons may be determined automatically, such as by an algorithm, or manually beforehand, such as by a user, an administrator, or a manufacturer. Sequencing the transmission of the beacons may not be necessary between WAPs 110 that are geographically too distance to hear each other's beacons.
[0023] In one embodiment, each of the WAPs 110 may be assigned an order number beforehand, such as by a user, administrator, or manufacturer. The order may be determined according to any method, such as a timing sequence, a location of the WAPs 110, or distances of the WAPs 110 from a central point. Thus, in FIG. 2, the first WAP 110-1, may be assigned a first order number while the nth WAP 110-n may be assigned nth order number. Then, during the BTP, each of the WAPs 110-1 to 110-n may listen for unmarked and/or marked beacons from nearby WAPs 110. As noted above, the beacon may include information identifying the WAP 110 that transmitted the beacon.
[0024] For instance, during a first iteration of the BTP, all the WAPs 110-1 to 110-n may transmit unmarked beacons. The first WAP 110-1 may determine that its turn to use the frequency channel A is next if it only hears unmarked beacons and has not previously heard any marked beacons for a first cycle. However, for subsequent cycles, the first WAP 110-1 may only determine that its turn to use the frequency channel A is next if it hears a marked beacon from the nth WAP 110-n during a last iteration of the CAP. Similarly, a remainder of the WAPs 110-2 to 110-n (where n is greater than 2) may determine that their turn to use the frequency channel A is next only if they hear a marked beacon from the previous WAP 110-1 to 110-(n-1) during a previous iteration of the CAP. For example, the fifth WAP 110-5 would determine that its turn to use the frequency channel A is next if it hears the marked beacon of the fourth WAP 110-4 during the latest iteration of the CAP. The current WAP 110 controlling the frequency channel A may need to be geographically close enough to at least the next WAP 110 receiving control of the frequency channel A such that the next WAP 110 may hear the marked beacon of the current WAP 110.
[0025] In another embodiment (not shown), the order for transferring control of the frequency channel A may be determined centrally instead of in a distributed manner. For example, a higher layer or powered controlling WAP (not shown) may detect all the beacons and determine an order in which the all the WAPs 110-1 to 110-n are to share the frequency channel A, such as based on MAC addresses of the WAPs and the like. In this case, the WAPs 110-1 to 11-n may require enough transmission power for their beacons to reach the controlling WAP and the controlling WAP may require enough transmission power to reach all the WAPs 110-1 to 110-n. In addition, the controlling WAP may supplement the above described distributed system, such as by helping to pass control of the frequency channel A when one of the WAPs 110 refuses to relinquish control of the frequency channel A.
[0026] Next, during the CAP, the WAP 110 that currently is determined to have access to the frequency channel A transmits a marked beacon. The beacon may be marked, for example, by setting a flag or bit. In one embodiment, a Point coordination function (PCF) of the IEEE 802.11 standard may be used, such that the marked beacon indicates a Contention Free Period (CFP) while an unmarked period indicates a Contention Period (CP).
[0027] In FIG. 2, the first WAP 110-1 transmits the marked beacon while a remainder of the WAPS 110, such as the nth WAP 110-n, transmit the unmarked beacon. The marked beacon may indicate to the first client devices 120-1 to prepare for communication with the first WAP 110-1 and that the first WAP 110-1 is in exclusive control of the frequency channel A. The unmarked beacon may indicate to a remainder of the CDs, such as the nth client device 120-n, to not prepare for any immediate communication with their associated WAP 110. The unmarked beacon may also indicate that the remainder of the plurality of WAPs are not in control of the frequency channel A to the remainder of the plurality of CDs 120-2 to 120-n (where n is greater than 2).
[0028] Next, the first WAP 110-1 may collect information from the one or more first client devices 120-1 during the CAP. If there is more than one first client device 120-1 , the first WAP 110-1 may sequentially poll the first client devices 120- 1, such as by transmitting Contention-Free-Poll (CF-Poll) packets. In response to being polled, the first devices 120-1 may transmit information to the first WAP-1. For example, the first devices 120-1 may transmit information collected by sensors, such as pressure and light data. A remainder of the WAPs 110, such as the nth WAP 110-n, do not communicate with any of the plurality of CDs 120-1 to 120-n during this CAP.
[0029] The first CDs 120-1 associated with the first WAP 110-1 at least one of awake and remain awake in response to receiving the marked beacon and/or being polled. During a remainder of the time, the first CDs 120-1 may remain in a low power state, such as a sleep, hibernate or off state, to conserve energy and/or increase a lifespan of the first CDs 120-1. For example, if the first CDs 120-1 are battery powered, staying in the lower power state may significantly increase a time before the battery is recharged and/or replaced. The remaining CDs 120-2 to 120- n associated with the remainder of the plurality of WAPs 110-2 to 120-n at least one of remain in and enter the low power state in response to receiving the unmarked beacon. Further, the remaining CDs 120-2 to 120-n may react similarly to the first CD 120-1 when receiving marked beacons.
[0030] In one embodiment, the first WAP 110-1 may transmit a first message, such as a CF-End Frame or token, during the CAP to at least one of the plurality of WAPs 120-2 to 120-n to indicate that the first WAP 120-1 has completed collecting information from the first CDs 120-1 and to indicate an end of the CAP, if the first WAP 110-1 completes collecting the information from all the first devices 110-1 within the CAP. Alternatively, the first WAP 110-1 may not transmit the first message when the WAP 110-1 completes collecting the information from all the first devices 110-1 before the CAP ends. In this case, the first WAP 110-1 may simply wait for the CAP end, instead of prematurely shortening the CAP.
[0031] However, if the first WAP 110-1 anticipates not completing collection of the information from the first CDs 120-1 during the CAP, the first WAP 110-1 may extend the CAP to complete collecting the information from all the first devices 110- 1. For example, at a threshold time period before the CAP is to end, the first WAP 110-1 may transmit or continue to transmit the marked beacon to extend a time interval of the CAP.
[0032] After the CAP is over, first WAP 110-1 transmits the collected information during OAP. The first WAP 110-1 may, for example, transmit the collected information to another of the WAPs 110-2 to 110-n and/or a higher level WAP or network element, such as a hub, router or gateway. The first WAP 110-1 may also transmit a second message during the OAP to the second WAP 110-2, The second message is to indicate that the second WAP 110-2 is to have exclusive control of the frequency channel A during a subsequent iteration of the CAP. Alternatively, the first WAP 110-1 may not the second message. Instead, the second WAP 110-2 may determine that is to have exclusive control of the frequency channel A during a subsequent iteration of the CAP upon hearing the marked beacon of the first WAP 110-1. The second WAP 110-2 may prepare a marked beacon to be transmitted during the subsequent iteration of the CAP, in response to learning it will next have exclusive control of the frequency channel A.
[0033] The OAP may be a time period where more than one of the WAPs 110-1 to 110-n may communicate using the frequency channel A. In addition, a new CD 120 being added to the network may also communicate using the frequency channel A during the OAP to indicate its presence to its associated WAP 110. However, non-new CDs 120 may not generally transmit information using the frequency channel A during the OAP. Due to simultaneous use of the frequency channel A by the WAPs 110 and/or new CDs 120, there may be interference or contention during the OAP. As a result, contention mechanisms may be used during this time period, such as a Distributed Coordination Function (DCF) of the 802.11 standard.
[0034] The BTP, CAP, and OAP sequentially iterate until all of the plurality of the WAPs 110-1 to 110-n have exclusively controlled the frequency channel A. As explained above, the transitions between the BTP, CAP and OAP may be determined asynchronously by at least one of the WAPs 110-1 to 110-n signaling an end or beginning of at least one of the BTP, CAP and OAP. Alternatively or in addition to, transitions between the BTP, CAP, and OAP may be timed to occur synchronously, such as by using a global timer. As a result, less signals may be transmitted by the WAPs 110-1 to 110-n between transitions of the BTP, CAP and OAP.
[0035] FIG. 3 is an example block diagram of a computing device 300 including instructions for transmitting information over a wireless network. In the embodiment of FIG. 3, the computing device 300 includes a processor 310 and a machine- readable storage medium 320. The machine-readable storage medium 320 further includes instructions 322, 324 and 326 for transmitting information over the wireless network.
[0036] The computing device 300 may be, for example, a router, a switch, a gateway, a server, a command center or any other type of user device capable of executing the instructions 322, 324 and 326. In certain examples, the computing device 300 may included or be connected to additional components such as memories, sensors, displays, wireless access points (WAP), client devices (CD), etc.
[0037] The processor 310 may be, at least one central processing unit (CPU), at least one semiconductor-based microprocessor, at least one graphics processing unit (GPU), other hardware devices suitable for retrieval and execution of instructions stored in the machine-readable storage medium 320, or combinations thereof. The processor 310 may fetch, decode, and execute instructions 322, 324 and 326 to implement for transmitting information over the wireless network. As an alternative or in addition to retrieving and executing instructions, the processor 310 may include at least one integrated circuit (IC), other control logic, other electronic circuits, or combinations thereof that include a number of electronic components for performing the functionality of instructions 322, 324 and 326.
[0038] The machine-readable storage medium 320 may be any electronic, magnetic, optical, or other physical storage device that contains or stores executable instructions. Thus, the machine-readable storage medium 320 may be, for example, Random Access Memory (RAM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a storage drive, a Compact Disc Read Only Memory (CD-ROM), and the like. As such, the machine-readable storage medium 320 can be non-transitory. As described in detail below, machine-readable storage medium 320 may be encoded with a series of executable instructions for transmitting information over the wireless network.
[0039] Moreover, the instructions 322, 324 and 326 when executed by a processor (e.g., via one processing element or multiple processing elements of the processor) can cause the processor to perform processes, such as, the process of FIG. 4. For example, the transmit beacon instructions 322 may be executed by the processor 310 to transmit a beacon from a first WAP (not shown) over a frequency channel usable by a second WAP (not shown), the frequency channel being part of an ISM radio band, during a BTP.
[0040] The collect information instructions 324 may be executed by the processor 310 to collect information from a first CD (not shown) associated with the first WAP, during a CAP, if the first WAP is determined to have exclusive control during the CAP. The transmit information instructions 326 may be executed by the processor 310 to transmit from the first WAP the collected information during an OAP.
[0041] The machine-readable storage medium 420 may also include instructions (not shown) to indicate to the second WAP that the second WAP is to receive exclusive control of the same frequency channel after the first WAP collects the information from the first CD. The first WAP collects the information from the first CD during a first iteration of the CAP and the second WAP collects information from a second CD during a second iteration of the CAP.
[0042] FIG. 4 is an example flowchart of a method 400 for transmitting information over a wireless network. Although execution of the method 400 is described below with reference to the wireless network 100, other suitable components for execution of the method 400 can be utilized. Additionally, the components for executing the method 400 may be spread among multiple devices. The method 400 may be implemented in the form of executable instructions stored on a machine-readable storage medium, such as storage medium 320, and/or in the form of electronic circuitry.

中文:
[0001]无线网络可以在诸如Wi-Fi的未授权频带运行。使用未授权频带的无线网络与使用授权频带的、诸如蜂窝网络或者WiMax网络的无线网络相比,可能具有更低的成本。例如,使用未授权频带的无线网络的部署、保养和系统成本可能低于使用授权频带的无线网络。
[0002]然而,使用未授权频带且尺寸相对大的无线网络可能不会有效运行。例如,在这样大的无线网络中,由于竞争、干扰、以及缺少确定性,信息可能丢失和/或重复传输。制造商、供应商和/或用户面临的挑战是提供用于在使用未授权频带的大无线网络中传输信息的更有效的方法。
[0004]图1是包含多个无线接入点(WAP)的无线网络的示例框图;
[0005]图2是图1的WAP的示例时序图;
[0006]图3是包含用于在无线网络中传输信息的指令的计算设备的示例框图;以及
[0007]图4是用于在无线网络中传输信息的方法的示例流程图。
[0008]下面的描述中给出具体细节,以提供对实施例的彻底理解。然而,本领域的普通技术人员可以理解,实施例可以被付诸实践而不用这些具体细节。例如,系统可以在框图中示出,为了不以不需要的细节使实施例模糊。在其他实例中,可以示出周知的过程、构造和技术,而没有不需要的细节,以避免使实施例模糊。
[0009]无线网络可以在未授权频带运行并使用比如Wi-Fi的标准,以与在授权频带运行相比节省成本。另外,对于授权和/或独占使用的频带在某些环境中可能并不总是可用的。除了避免授权费,使用未授权频带的无线网络还可以具有更低的部署、保养和系统成本。
[0010]然而,在更大的无线网络中,诸如无线接入点(WAP)或者客户端设备(CD)的、使用未授权频带的相同频道的网元之间的干扰可能变得太大。例如,诸如油气勘探系统的大无线网络可能包含数千至数百万的诸如传感器的CD,其在相同频道中向一个或多个WAP发送信息。该一个或多个WAP可以将该信息转发给中心实体,诸如中心命令中心。在这种情况下,因为CD之间的干扰和/或WAP尝试在相同频道同时通信,信息的可靠输送可能很困难。此外,如果CD和/或WAP在诸如电池的有限的电源上运行,那么由于向射频(RF)干扰丢失的信息的重新传输,电源可能变得更快耗尽。此外,由于RF干扰,尝试接收和/或传输信息可能会浪费时间。
[0011]实施例可以允许使用未授权频带的大无线网络以减小的RF干扰来运行,同时还节省了更多功率,并且减少了传输或接收信息的次数。例如,多个WAP可以共享作为工业、科学和医疗(ISM)无线电频带的一部分的相同频道。多个CD中的每个可以与WAP中的一个顺着该相同频道通信。
[0013]因此,通过将单个、相同频道的所有权限制为一次一个WAP,并通过在相关联的WAP独占控制该相同频道的时间期间,调度CD的轮询,实施例可以提供更多的公平,节省功率并减少信息接收/传输次数。此外,通过使用ISM无线电频带,实施例可以更容易在不同环境、诸如世界的不同部分部署,因为保护授权频带的固有的成本和限制可能不存在。
[0014]参考附图,图1是包含多个WAP 110-1至110-n和多个客户端设备120-1至120-n的无线网络100的示例框图,其中n是自然数。无线网络100可以是使用传输系统的任何类型的网络,包含来自工业、科学和医疗(ISM)无线电频带频谱的无线电波。ISM无线电频带一般用于未授权运行。因此,WAP例如可以是无线LAN设备,其使用下面之一的频道:2450MHz频带(蓝牙)、5800MHz频带(HIPERLAN)、2450和5800MHz频带(IEEE802.11/WIFI)、和/或915和2450MHz频带(IEEE802.15.4 ZigBee)。
[0015]图1示出多个WAP 110-1至110-n,其中至少2个WAP示出为共享相同频道A,该相同频道A是ISM频带的一部分,诸如上述列出的频道之一。术语“频道”可以指具体频率、频率对和/或频率带。例如,频道2.450千兆赫(GHz)可以指2.450GHz的中心频率以及2.400GHz至2.500GHz的频率范围。
[0016]WAP 110-1至110-n可以是允许从CD 120-1至120-n采集的信息中继至无线网络100的其余部分(诸如路由器、交换机、网关、服务器、命令中心等)的任何类型的设备。CD 120-1至120-n可以包含能够测量、采集、存储、和/或传输信息至WAP 110-1至110-n中的一个的任何类型的设备,诸如传感器,发射机等。例如,无线网络100的实施例可以包含约100个WAP 110-1至110-100、以及与每个WAP 110相关联的大约100个CD 120。每个WAP 110及其相关联的一个或多个CD 120可以称作小区。例如,第一WAP 110-1和第一设备120-1可以形成第一小区,而第n个WAP 110-n和第n个设备120-n可以形成第n小区。
[0017]WAP 110-1至110-n例如可以包含硬件设备,该硬件设备包含用于实现下述功能的电子电路,诸如控制逻辑和/或存储器。此外,或者作为替代,WAP 110-1至110-n可以实现为在机器可读存储介质中编码并可由处理器执行的一系列指令。
[0019]如图1所示,WAP 110-1至110-n中的每个在信标传输周期(BTP)期间在频道A中传输信标。信标可以是连续的或者周期的无线电信号,其具有有限的信息内容,诸如SSID、信道号、以及诸如WEP(有线等效保密)或者WPA(Wi-Fi保护接入)的安全性协议。信标可以以规律的间隔由WAP110-1至110-n传输。
[0020]接下来,多个WAP 110-1至110-n的传输信标的第一WAP 110-1将在控制接入周期(CAP)期间从与第一WAP 110-1相关联的多个CD 120-1中的至少一个采集信息。最后,在开放接入周期(OAP)期间,第一WAP 110-1传输采集的信息。关于图2,将会更详细地描述BTP、CAP和OAP。
[0021]图2是图1的WAP 110的示例时序图。虽然图2仅示出对于2个WAP110-1和110-n的时序图,但BTP、CAP和OAP可以对WAP 110-1至110-n中的每个进行重复。当所有的WAP 110-1至110-n已接收到使用频道A的机会时,单个周期完成。例如,BTP的长度可以是20毫秒(ms),CAP可以是60ms,并且OAP可以是70ms。但整个周期可以是20秒。因此,BTP、CAP和OAP的每个可以每150ms重复,直至所有的WAP 110-1至110-n已轮到它们来使用频道A。例如,如果有100个WAP 110-1至110-100,那么所有的WAP 110-1至110-100使用频道A可能花费15秒(150ms x 100)。因此,周期可以是15秒,或者周期可以保持得更长、诸如20秒,其中周期的最后5秒对频道A的其他用途开放。一旦周期结束,新的周期开始,每个周期以第一WAP 110-1重新开始。
[0022]如图2所示,在BTP期间,第一WAP 110-1和第n WAP 110-n不同时或者在相同的时间传输信标。反而,在BTP期间WAP 110-1至110-n中的每个都顺序地传输信标,以便避免或减小来自不同WAP 110碰撞的信标的射频干扰。用于传输未标记信标的顺序可以诸如通过算法自动确定,或者事先诸如由用户、管理员、或者制造商手动确定。可能不需要在地理上距离太远以至于听不到彼此的信标的WAP 110之间对信标的传输进行排序。
[0023]在一个实施例中,WAP 110中的每个可以事先诸如由用户、管理员、或者制造商分配序号。该顺序可以根据任何方法确定,诸如时序、WAP 110的地点、或者WAP 110从中心点起的距离。因此,在图2中,第一WAP 110-1可以分配第一序号,而第n WAP 110-n可以分配第n序号。然后,在BTP期间,WAP 110-1至110-n中的每个可以从附近的WAP 110监听未标记的和/或标记的信标。如上所述,信标可以包含识别传输该信标的WAP 110的信息。
[0024]例如,在BTP的第一迭代期间,所有的WAP 110-1至110-n可以传输未标记的信标。如果第一WAP 110-1在第一周期仅听到未标记的信标并且之前没有听到任何标记的信标,那么第一WAP 110-1可以确定接下来轮到其使用频道A。然而,在接下来的周期,如果WAP 110-1在CAP的最后迭代期间从第n WAP 110-n听到标记的信标,那么第一WAP 110-1可以仅确定接下来轮到其使用频道A。类似地,仅当其余的WAP 110-2至110-n(其中n大于2)在CAP的上一次迭代期间从先前的WAP 110-1至110-(n-1)听到标记的信标,那么其余的WAP 110-2至110-n(其中n大于2)可以确定接下来轮到其使用频道A。例如,如果第五WAP 110-5在CAP的最新迭代期间听到第四WAP 110-4的标记的信标,那么第五WAP 110-5确定接下来轮到其使用频道A。控制该频道A的当前WAP 110可能需要在地理上足够接近接收该频道A的控制的至少接下来的WAP 110,使得接下来的WAP 110可以听到当前WAP 110的标记的信标。
[0025]在另一个实施例(未示出)中,用于传送频道A的控制的顺序可以在中心确定,而非以分布式方式确定。例如,更高层的或者供电的控制WAP(未示出)可以检测所有信标并确定顺序,其中所有WAP 110-1至110-n要诸如基于WAP的MAC地址等来按照所述顺序共享频道A。在这种情况下,WAP 110-1至110-n可以要求足够的传输功率使其信标到达控制WAP,并且控制WAP可以要求足够的传输功率以到达所有WAP 110-1至110-n。此外,控制WAP可以诸如通过当WAP 110中的一个拒绝放弃频道A的控制时帮助传递频道A的控制,来补充上面描述的分布式系统。
[0026]接下来,在CAP期间,当前被确定为能访问频道A的WAP 110传输标记的信标。信标例如可以通过设定标志或者位来标记。在一个实施例中,可以使用IEEE 802.11标准的点协调功能(PCF),使得标记的信标指示免竞争周期(CFP),而未标记的周期指示竞争周期(CP)。
[0027]在图2中,第一WAP 110-1传输标记的信标,而其余的WAPS 110(诸如第n WAP 110-n)传输未标记的信标。标记的信标可以向第一客户端设备120-1指示以准备与第一WAP 110-1通信,并且该第一WAP 110-1独占频道A的控制。未标记的信标可以指示其余的CD(诸如第n个客户端设备120-n)以不准备与其相关联的WAP 110进行任何即时通信。未标记的信标还可以向其余的多个CD 120-2至120-n(其中n大于2)指示其余的多个WAP不控制频道A。
[0028]接下来,第一WAP 110-1可以在CAP期间从一个或多个第一客户端设备120-1采集信息。如果有多于一个的第一客户端设备120-1,那么第一WAP 110-1可以诸如通过传输免竞争轮询(CF-Poll)数据包,来顺序地轮询第一客户端设备120-1。响应于被轮询,所述第一设备120-1可以将信息传输给第一WAP-1。例如,第一设备120-1可以传输由传感器采集的信息,诸如压力和光数据。在该CAP期间,其余的WAP 110(诸如第n WAP 110-n)不与多个CD 120-1至120-n的任一通信。
[0029]响应于接收到标记的信标和/或被轮询,与第一WAP 110-1相关联的第一CD 120-1进行以下中的至少一个:唤醒和保持唤醒。在该时间的其余期间,第一CD 120-1可以保持为低功率状态,诸如睡眠、休眠或者断电状态,以节省能量和/或增加第一CD 120-1的寿命。例如,如果第一CD 120-1是电池供电的,那么处于低功率状态可以显著增加在电池再充电和/或更换之前的时间。响应于接收该未标记的信标,与其余的多个WAP 110-2至120-n相关联的其余的CD 120-2至120-n执行以下中的至少一个:保持在低功率状态和进入低功率状态。此外,当接收了标记的信标时,其余的CD 120-2至120-n可以类似于第一CD 120-1来反应。
[0030]在一个实施例中,在CAP期间,第一WAP 110-1可以传输诸如CF结束帧或者令牌的第一消息至多个WAP 120-2至120-n中的至少一个,以指示该第一WAP 120-1已完成从第一CD 120-1采集信息,并且当第一WAP110-1在CAP内完成从所有第一设备110-1采集信息时,指示CAP的结束。或者,当在CAP结束之前WAP 110-1完成从所有第一设备110-1采集信息时,第一WAP 110-1可以不传输第一消息。在这种情况下,第一WAP 110-1可以简单地等CAP结束,而不是过早缩短CAP。
[0031]然而,如果第一WAP 110-1预料到没有在CAP期间完成从第一CD120-1采集信息,那么第一WAP 110-1可以延长CAP来完成从所有第一设备110-1采集信息。例如,在CAP要结束之前的阈值时间周期,第一WAP110-1可以传输或继续传输标记的信标,以延长CAP的时间间隔。
[0032]在CAP结束之后,第一WAP 110-1在OAP期间传输采集的信息。第一WAP 110-1例如可以将采集的信息传输至WAP 110-2至110-n的另一个和/或更高级别的WAP或者网元,诸如集线器、路由器或者网关。第一WAP110-1还可以在OAP期间将第二消息传输至第二WAP 110-2。该第二消息指示该第二WAP 110-2在CAP的接下来的迭代期间具有频道A的独占控制。或者,第一WAP 110-1可以不传输第二消息。作为替代,当听到第一WAP 110-1的标记的信标时,第二WAP 110-2可以确定在CAP的接下来的迭代期间具有频道A的独占控制。第二WAP 110-2可以响应于得知其将接下来具有频道A的独占控制,准备在CAP的接下来的迭代期间将传输的标记的信标。
[0033]OAP可以是多于一个的WAP 110-1至110-n可以使用频道A来通信的时间周期。此外,增加至网络的新的CD 120也可以在OAP期间使用频道A通信,以向其相关联的WAP 110指示其存在。然而,非新的CD 120一般可以不在OAP期间使用频道A传输信息。由于由WAP 110和/或新的CD120同时使用频道A,在OAP期间可能有干扰或者竞争。作为结果,在该时间周期可以使用竞争机制,诸如802.11标准的分布式协调功能(DCF)。
[0034]BTP、CAP和OAP顺序地迭代,直至所有的多个WAP 110-1至110-n已独占地控制了频道A。如上所述,BTP、CAP和OAP之间的过渡可以由以下步骤异步确定:至少一个WAP 110-1至110-n以信号发送BTP、CAP和OAP中至少一个的结束或者开始。替代地或者额外地,BTP、CAP和OAP之间的过渡可以诸如通过使用全球计时器被计时以同步发生。作为结果,在BTP、CAP和OAP的过渡之间可以由WAP 110-1至110-n传输更少的信号。
[0035]图3是包含用于在无线网络中传输信息的指令的计算设备300的示例框图。在图3的实施例中,计算设备300包含处理器310和机器可读存储介质320。机器可读存储介质320还包含用于在无线网络中传输信息的指令322、324和326。
[0036]计算设备300例如可以是路由器、交换机、网关、服务器、命令中心或者能够执行指令322、324和326的任何其他类型的用户设备。在某些示例中,计算设备300可以包含或者连接至附加部件,诸如存储器、传感器、显示器、无线接入点(WAP)、客户端设备(CD)等。
[0037]处理器310可以是至少一个中央处理单元(CPU)、至少一个基于半导体的微处理器、至少一个图形处理单元(GPU)、适于取回并执行在机器可读存储介质320中存储的指令的其他硬件设备、或者其组合。处理器310可以抓取、解码、并且执行指令322、324和326,以实现在无线网络中传输信息。作为替代或者附加于取回并执行指令,处理器310可以至少包含一个集成电路(IC)、其他控制逻辑、其他电子电路、或者包含用于执行指令322、324和326的功能的多个电子部件的组合。
[0038]机器可读存储介质320可以是任何电子、磁、光、或者含有或存储可执行指令的其他物理存储设备。因此,机器可读存储介质320例如可以是随机存取存储器(RAM)、电可擦除可编程只读存储器(EEPROM)、存储驱动器、光盘只读存储器(CDROM)等。这样,机器可读存储介质320可以是非暂时性的。如下文具体描述的那样,机器可读存储介质320可以编码有一系列可执行指令,用于在无线网络中传输信息。
[0039]此外,当由处理器执行(例如经由处理器的一个处理元件或者多个处理元件)时,指令322、324和326可以使处理器执行诸如图4的过程的处理。例如,传输信标指令322可以由处理器310执行,用于在BTP期间通过第二WAP(未示出)可用的频道从第一WAP(未示出)传输信标,所述频道是ISM无线电频带的一部分。
[0040]如果第一WAP被确定为在CAP期间具有独占控制,那么采集信息指令324可以由处理器310执行以在CAP期间从与第一WAP相关联的第一CD(未示出)采集信息。传输信息指令326可以由处理器310执行,以在OAP期间从第一WAP传输采集的信息。
[0041]机器可读存储介质420还可以包含指令(未示出),以在第一WAP从第一CD采集信息之后,向第二WAP指示:第二WAP将接收相同频道的独占控制。在CAP的第一迭代期间,第一WAP从第一CD采集信息;并且在CAP的第二迭代期间,第二WAP从第二CD采集信息。
[0042]图4是用于通过无线网络传输信息的方法400的示例流程图。尽管下文中方法400的执行是参考无线网络100描述的,但可以利用用于执行方法400的其他适当的部件。附加地,用于执行方法400的部件可以在多个设备间分散。方法400可以以存储在机器可读存储介质(诸如存储介质320)上的可执行指令形式和/或电子电路的形式实现。