昆明网站开发,怎样实现wordpress订单提醒功能,制作一个网站需要多长时间,设计接单赚钱平台物理信道有多种类型。所有蓝牙物理信道的特点都是一组物理层的频率与时间参数相结合#xff0c;并受到空间因素的限制。对于基本的和经过调整的蓝牙组网(piconet)所用物理信道#xff0c;跳频用于定期改变频率#xff0c;以减少干扰影响#xff0c;同时也是出于监管原因。 …
物理信道有多种类型。所有蓝牙物理信道的特点都是一组物理层的频率与时间参数相结合并受到空间因素的限制。对于基本的和经过调整的蓝牙组网(piconet)所用物理信道跳频用于定期改变频率以减少干扰影响同时也是出于监管原因。 在 BR/EDR 核心系统中对等(peer)设备使用共享物理信道进行通信。为此它们的收发器需要同时调谐到相同的物理层频率并且需要在彼此距离的合适范围内。由于射频载波的数量有限而且许多蓝牙设备可能在同一空间和时间区域内独立运行因此很有可能出现两个独立蓝牙设备的收发器调谐到相同射频载波的情况从而导致物理信道碰撞。为了减少这种碰撞带来的不良影响物理信道上的每次传输都以一个接入代码开始该代码被设置为与设备的物理信道相关代码。该信道接入码是物理信道的属性。接入码存在于每个传输数据包的开头。接入码用于定时同步、偏移补偿、寻呼和查询。 定义了多个 BR/EDR 物理通道。每个通道都经过优化用于不同的目的 其中两个物理信道基本 piconet 信道和适配 piconet 信道用于连接设备之间的通信并与特定 piconet 相关联。 其他 BR/EDR 物理信道用于发现查询扫描信道和连接寻呼扫描信道蓝牙设备。 设备使用同步扫描物理信道获取无连接从属广播物理链路的时序和频率信息或恢复当前 piconet 时钟。
蓝牙设备在任何时候都只能使用一个 BR/EDR 物理通道。为了支持多个并发操作设备在信道之间使用了时分复用技术。 A number of types of physical channel are defined. All Bluetooth physical channels are characterized by a set of PHY frequencies combined with temporal parameters and restricted by spatial considerations. For the basic and adapted piconet physical channels frequency hopping is used to change frequency periodically to reduce the effects of interference and for regulatory reasons. In the BR/EDR core system, peer devices use a shared physical channel for communication. To achieve this their transceivers need to be tuned to the same PHY frequency at the same time, and they need to be within a nominal range of each other. Given that the number of RF carriers is limited and that many Bluetooth devices may be operating independently within the same spatial and temporal area there is a strong likelihood of two independent Bluetooth devices having their transceivers tuned to the same RF carrier, resulting in a physical channel collision. To mitigate the unwanted effects of this collision each transmission on a physical channel starts with an access code that is used as a correlation code by devices tuned to the physical channel. This channel access code is a property of the physical channel. The access code is present at the start of every transmitted packet. Access code is used for timing synchronization, offset compensation, paging and inquiry. Several BR/EDR physical channels are defined. Each is optimized and used for a different purpose.
* Two of these physical channels (the basic piconet channel and adapted piconet channel) are used for communication between connected devices and are associated with a specific piconet.
* Other BR/EDR physical channels are used for discovering (the inquiry scan channel) and connecting (the page scan channel) Bluetooth devices.
* The synchronization scan physical channel is used by devices to obtain timing and frequency information about the Connectionless Slave Broadcast physical link or to recover the current piconet clock. A Bluetooth device can only use one BR/EDR physical channel at any given time. In order to support multiple concurrent operations the device uses timedivision multiplexing between the channels. 基础组网信道 (Basic piconet channel) 在正常运行期间基本piconet 通道用于连接设备之间的通信。 特点 基本 piconet 信道的特点是通过 PHY 信道进行伪随机序列跳转。跳转序列对 piconet 来说是唯一的由主设备的蓝牙设备地址决定。跳转序列的相位由主设备的蓝牙时钟决定。所有参与 piconet 的蓝牙设备都与信道保持时间和跳频同步。 信道被划分为多个时隙每个时隙对应一个物理层跳频。连续的跳频对应不同的物理层跳频。时隙根据 piconet 主站的蓝牙时钟编号。数据包由参与 piconet 的蓝牙设备传输并以时隙边界为起点。每个数据包以信道访问代码开始该代码来自 piconet 主设备的蓝牙设备地址。 在基本 piconet 信道上主设备控制着信道的访问。主设备只在偶数时隙开始传输。主站传输的数据包与时隙起始点保持一致并确定 piconet 时序。主站传输的数据包最多可占用五个时隙具体取决于数据包的类型。 拓扑结构 一个基本的 piconet 信道可由任意数量的蓝牙设备共享仅受 piconet 主设备可用资源的限制。只有一个设备是 piconet 主设备所有其他设备都是 piconet 从设备。所有通信都在主设备和从设备之间进行。piconet 通道上的从设备之间不能直接通信。 不过一个 piconet 可支持的逻辑传输数量是有限制的。这意味着虽然共享一个信道的蓝牙设备的数量在理论上没有限制但这些设备中能够主动与主设备交换数据的数量是有限制的。 Basic piconet channel The basic piconet channel is used for communication between connected devices during normal operation. Characteristics
* The basic piconet channel is characterized by a pseudo-random sequence hopping through the PHY channels. The hopping sequence is unique for the piconet and is determined by the Bluetooth device address of the master. The phase in the hopping sequence is determined by the Bluetooth clock of the master. All Bluetooth devices participating in the piconet are time- and hop synchronized to the channel. * The channel is divided into time slots where each slot corresponds to an PHY hop frequency. Consecutive hops correspond to different PHY hop frequencies. The time slots are numbered according to the Bluetooth clock of the piconet master. Packets are transmitted by Bluetooth devices participating in the piconet aligned to start at a slot boundary. Each packet starts with the channel access code, which is derived from the Bluetooth device address of the piconet master. * On the basic piconet channel the master controls access to the channel. The master starts its transmission in even-numbered time slots only. Packets transmitted by the master are aligned with the slot start and define the piconet timing. Packets transmitted by the master may occupy up to five time slots depending on the packet type. Topology
A basic piconet channel may be shared by any number of Bluetooth devices, limited only by the resources available on the piconet master device. Only one device is the piconet master, all others being piconet slaves. All communication is between the master and slave devices. There is no direct communication between slave devices on the piconet channel. There is, however, a limitation on the number of logical transports that can be supported within a piconet. This means that although there is no theoretical limit to the number of Bluetooth devices that share a channel there is a limit to the number of these devices that can be actively involved in exchanging data with the master. 适配 piconet 信道 (Adapted piconet channel) 基本 piconet 通道用于连接设备之间的正常通信。适配 piconet 信道与基本 piconet 通道有两个不同之处 1, 从设备传输的频率与主设备在前一次传输中使用的频率相同。换句话说主设备和随后的从设备数据包之间不需要重新计算频率。 2, 调整后的 piconet 信道可基于少于全部 79 个频率。一些频率可被标记为 unused从而被排除在跳频模式之外。79 个频率的其余部分则包括在内。这两套频率集合的区别就是当基本伪随机跳频序列选择了一个unused的频率时会从used的频率中选择一个频率替换。在同一个适配piconet信道上不同的物理链路所使用的频率集可能不同。 适配 piconet 信道是指连接设备之间的蓝牙通信中使用的一种机制。在蓝牙设备网络 piconet 中适配 piconet 信道可确保从设备传输所用的频率与主设备前一个传输所用的频率相同。这种机制有助于在 piconet 内保持同步和高效通信。 Adapted piconet channel
The basic piconet channel is used for communication between connected devices during normal operation. It differs from the basic piconet channel in two ways: 1. the frequency on which a slave transmits is the same as the frequency used by its master in the preceding transmission. In other words the frequency is not recomputed between master and subsequent slave packets. 2. the adapted piconet channel may be based on fewer than the full 79 frequencies. A number of frequencies may be excluded from the hopping pattern by being marked as “unused”. The remainder of the 79 frequencies are included. The two sequences are the same except that whenever the basic pseudo-random hopping sequence selects an unused frequency, it is replaced with an alternative chosen from the used set. The set of frequencies used may vary between different physical links on the same adapted piconet channel. The adapted piconet channel refers to a mechanism used in Bluetooth communication between connected devices. In a piconet, which is a network of Bluetooth devices, the adapted piconet channel ensures that the frequency used by the slave device for transmission is the same as the frequency used by the preceding master device transmission. This mechanism helps maintain synchrony and efficient communication within the piconet. 查询扫描通道(Inquiry scan channel) 为使设备被发现需要使用查询扫描信道。可被发现的设备在其查询扫描信道上监听查询请求然后发送对该请求的响应。 为了让一个设备发现其他设备它会以一种伪随机方式遍历跳转所有可能的查询扫描信道频率在每个频率上发送查询请求并监听任何响应。 特点: 查询扫描信道采用较慢的跳频模式并使用访问代码来区分使用不同物理信道的两个同地设备偶尔占用同一无线电频率的情况。 查询扫描信道上使用的访问代码来自所有蓝牙设备共享的一组保留查询访问代码。其中一个访问代码用于一般查询另外一些访问代码保留用于有限查询。每个设备都可以访问多个不同的查询扫描通道。由于所有这些信道都有相同的跳频模式如果一个设备能同时关联多个访问代码它就可以同时占用一个以上的查询扫描信道。 使用其中一个查询扫描信道的设备在该信道上一直处于被动状态直到收到另一个蓝牙设备在该信道上发出的查询信息。这可以通过相应的查询访问代码来识别。然后查询扫描设备将按照查询响应程序向查询设备返回响应。 为了发现其他蓝牙设备设备会使用查询扫描通道发送查询请求。由于事先不知道要发现的设备因此无法知道查询扫描信道的确切特性。 设备会利用查询扫描信道跳频次数较少、跳频速度较慢的特点。查询设备在每个查询扫描跳频上发送查询请求并等待查询响应。由于传输速度较快查询设备可以在较短时间内覆盖所有查询扫描频率。 拓扑结构: 发起查询的设备和可发现设备使用简单的数据包交换来实现查询功能。在此过程中形成的拓扑结构是一个简单而短暂的点对点连接。 Inquiry scan channel * In order for a device to be discovered, an inquiry scan channel is used. A discoverable device listens for inquiry requests on its inquiry scan channel and then sends a response to that request. * In order for a device to discover other devices, it iterates (hops) through all possible inquiry scan channel frequencies in a pseudo-random fashion, sending an inquiry request on each frequency and listening for any response. Characteristics * Inquiry scan channels follow a slower hopping pattern and use an access code to distinguish between occasional occupancy of the same radio frequency by two co-located devices using different physical channels. * The access code used on the inquiry scan channel is taken from a reserved set of inquiry access codes that are shared by all Bluetooth devices. One access code is used for general inquiries, and a number of additional access codes are reserved for limited inquiries. Each device has access to a number of different inquiry scan channels. As all of these channels share an identical hopping pattern, a device may concurrently occupy more than one inquiry scan channel if it is capable of concurrently correlating more than one access code. * A device using one of its inquiry scan channels remains passive on that channel until it receives an inquiry message on this channel from another Bluetooth device. This is identified by the appropriate inquiry access code. The inquiry scanning device will then follow the inquiry response procedure to return a response to the inquiring device. * In order for a device to discover other Bluetooth devices it uses the inquiry scan channel to send inquiry requests. As it has no prior knowledge of the devices to discover, it cannot know the exact characteristics of the inquiry scan channel. * The device takes advantage of the fact that inquiry scan channels have a reduced number of hop frequencies and a slower rate of hopping. The inquiring device transmits inquiry requests on each of the inquiry scan hop frequencies and listens for an inquiry response. Transmissions are done at a faster rate, allowing the inquiring device to cover all inquiry scan frequencies in a reasonably short time period. Topology
Inquiring and discoverable devices use a simple exchange of packets to fulfill the inquiring function. The topology formed during this transaction is a simple and transient point-to-point connection. 寻呼扫描信道(Page scan channel) 一个可连接设备准备接受连接的设备在其寻呼扫描信道上监听寻呼请求一旦收到就会与该设备进行一系列信息交换。 一个设备要连接到另一个设备需要以一种伪随机方式遍历跳转所有寻呼扫描信道频率在每个频率上发送寻呼请求并监听响应。 特点 寻呼扫描信道使用从扫描设备的蓝牙设备地址中提取的访问代码来识别信道上的通信。寻呼扫描信道使用的跳频速率比基本和适配 piconet 信道的跳频速率慢。跳频选择算法使用扫描设备的蓝牙设备时钟作为输入。 使用寻呼扫描信道的设备在收到另一个蓝牙设备的寻呼请求之前一直处于被动状态。这可以通过寻呼扫描信道访问代码来识别。然后两台设备将按照寻呼程序建立连接。在成功完成寻呼程序后两台设备将切换到基本的 piconet 信道该信道的特点是寻呼设备为主设备。 为了与另一个蓝牙设备连接设备会使用目标设备的寻呼扫描信道来发送寻呼请求。如果寻呼设备不知道目标设备寻呼扫描信道的相位就无法知道目标设备当前的跳频。寻呼设备在每个寻呼扫描跳频上发送页面请求并等待寻呼响应。这样做的跳频速度较快使寻呼设备能在合理的短时间内覆盖所有寻呼扫描频率。 寻呼设备可能对目标设备的蓝牙时钟有一定的了解在两台设备之前的查询交易中显示或由于之前与设备共同参与 piconet 的结果在这种情况下它能够预测目标设备寻呼扫描信道的相位。它可以利用这一信息优化寻呼和寻呼扫描过程的同步加快连接的建立。 拓扑结构 寻呼和可连接设备通过简单的数据包交换来实现寻呼功能。在此过程中形成的拓扑结构是一个简单而短暂的点对点连接。 Page scan channel * A connectable device (one that is prepared to accept connections) listens for a page request on its page scan channel and, once received, enters into a sequence of exchanges with this device.
* In order for a device to connect to another device, it iterates (hops) through all page scan channel frequencies in a pseudorandom fashion, sending a page request on each frequency and listening for a response. Characteristics * The page scan channel uses an access code derived from the scanning device’s Bluetooth device address to identify communications on the channel. The page scan channel uses a slower hopping rate than the hop rate of the basic and adapted piconet channels. The hop selection algorithm uses the Bluetooth device clock of the scanning device as an input. * A device using its page scan channel remains passive until it receives a page request from another Bluetooth device. This is identified by the page scan channel access code. The two devices will then follow the page procedure to form a connection. Following a successful conclusion of the page procedure both devices switch to the basic piconet channel that is characterized by having the paging device as master. * In order for a device to connect to another Bluetooth device it uses the page scan channel of the target device in order to send page requests. If the paging device does not know the phase of the target device’s page scan channel it therefore does not know the current hop frequency of the target device. The paging device transmits page requests on each of the page scan hop frequencies and listens for a page response. This is done at a faster hop rate, allowing the paging device to cover all page scan frequencies in a reasonably short time period. * The paging device may have some knowledge of the target device’s Bluetooth clock (indicated during a previous inquiry transaction between the two devices, or as a result of a previous involvement in a piconet with the device), in this case it is able to predict the phase of the target device’s page scan channel. It may use this information to optimize the synchronization of the paging and page scanning process and speed up the formation of the connection. Topology Paging and connectable devices use a simple exchange of packets to fulfill the paging function. The topology formed during this transaction is a simple and transient point-to-point connection. 同步扫描信道(Synchronization scan channel) 为了接收 CSB 逻辑传输上发送的数据包设备必须首先获取这些数据包的时序和频率信道的信息。如果设备错过了粗时钟(Coarse Clock Adjustment)调整通知则需要恢复当前的 piconet 时钟。同步扫描信道就是为此而提供的。扫描设备在同步扫描通道上监听同步列车数据包。一旦收到同步列车数据包设备就可以停止监听同步列车数据包因为它已经掌握了开始接收 CSB 逻辑传输上发送的数据包或恢复 piconet 时钟所需的时序和频率信息。 特点 同步扫描信道使用从同步列车发送器的蓝牙设备地址导出的访问代码来识别信道上的同步列车数据包。一旦收到同步列车数据包扫描 BR/EDR 控制器就可以开始接收 CSB 逻辑传输上发送的数据包具体取决于主机的需求和任何适用的配置文件。 拓扑结构 扫描过程中形成的拓扑结构是瞬时和一点对多点的。可以有数量不限的扫描设备同时接收来自同一同步列车发送器的同步列车数据包。 Synchronization scan channel In order to receive packets sent on the CSB logical transport, a device must first obtain information about the timing and frequency channels of those packets. If a device misses a Coarse Clock Adjustment notification, it needs to recover the current piconet clock. The synchronization scan channel is provided for these purposes. A scanning device listens for synchronization train packets on the synchronization scan channel. Once a synchronization train packet is received, the device may stop listening for synchronization train packets because it has the timing and frequency information necessary to start receiving packets sent on the CSB logical transport or to recover the piconet clock. Characteristics
The synchronization scan channel uses an access code derived from the Bluetooth device address of the synchronization train transmitter to identify synchronization train packets on the channel. Once a synchronization train packet is received, the scanning BR/EDR Controller may start receiving packets sent on the CSB logical transport, depending on the needs of the Host and any applicable profile(s). Topology
The topology formed during this scan is transient and point-to-multipoint. There can be an unlimited number of scanning devices simultaneously receiving synchronization train packets from the same synchronization train transmitter. 参考
1Overview of BR/EDR Physical Channels
BR/EDR channels
