| 单词 | BOOTP (BOOTstrap Protocol) |
| 释义 | BOOTP (BOOTstrap Protocol) Alternatively, the data channel can be supported in symmetric mode of up to 432.6 Kbps. As yet another alternative, Bluetooth supports up to three simultaneous synchronous packet voice channels, or a channel that simultaneously supports both asynchronous data and synchronous voice. Bluetooth supports full-duplex (FDX) communications using time division duplex (TDD) as the access method. Voice coding employs the continuously variable slope delta modulation (CVSDM). Bluetooth specifies 16 packet types, including 4 types of control packets and 12 types of data packets.There are 3 types of voice packets, each running at a rate of 64 kbps, including overhead and, in some cases, a forward error control (FEC) mechanism. In the event that an error is detected in the user payload of a packet transmitted over the ACL, Bluetooth specifies the use of an automatic repeat request (ARQ) for retransmission of errored packets. The variable-length packet is limited to 366 bits, although the theoretical limit is 625 bits (62.5 µs × 1 Mbps = 625 bits).The limit of 366 provides the transmitters and receivers with enough time to hop to the next frequency and stabilize.As the access code and packet header consume 126 bits, the payload cannot exceed 240 bits, or 30 octets.There is a provision for multislot packets in support of larger payloads.The payload includes an error control mechanism in the form of a cyclic redundancy check (CRC). Bluetooth operates in point-to-point, point-to-multipoint, and mesh configurations. As many as eight devices can link together in a piconet, or very small network, with as many as seven devices slaved to a single master. Multiple, overlapping piconets can form a scatternet. See also ACL, ARQ, asymmetric, asynchronous, CVSDM, FDX, FEC, FHSS, ISM, master/slave, piconet, point-to-multipoint, point-to-point, scatternet, SCO, symmetric, synchronous, TDD, and WPAN. |
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