List of PPDUs Supported in 802.11b
What is a PPDU in IEEE 802.11b?
PPDU stands for Physical Protocol Data Unit, which is the data unit transmitted at the physical layer.
What are the main components of the 802.11b PPDU?
The PPDU consists of a preamble, a header (PLCP header), and a PSDU (the MAC frame payload).
What is the purpose of the preamble in 802.11b PPDU?
The preamble is used for synchronization, signal detection, and channel estimation.
How long is the preamble in 802.11b PPDU?
The preamble duration is typically 144 microseconds in long preamble mode.
What is the PLCP header in 802.11b?
The Physical Layer Convergence Protocol (PLCP) header contains information about the data rate and length of the PSDU.
What modulation techniques does 802.11b PPDU use?
It uses Direct Sequence Spread Spectrum (DSSS) and Complementary Code Keying (CCK) for different data rates.
What data rates does 802.11b PPDU support?
It supports 1, 2, 5.5, and 11 Mbps data rates.
How is the length of the PSDU specified in the PPDU?
The PLCP header includes a length field indicating the number of bytes in the PSDU.
What is the difference between long and short preamble in 802.11b?
Short preamble reduces the preamble time to 72 microseconds to increase efficiency but requires compatible devices.
How does the receiver use the PPDU preamble?
The receiver uses it to synchronize its clock and prepare for demodulation of the incoming data.
What is the PSDU in the context of PPDU?
The Physical Layer Service Data Unit (PSDU) contains the MAC frame data that is transmitted.
How is error detection handled in 802.11b PPDU?
Error detection is primarily handled at the MAC layer via CRC, but PHY layer coding helps reduce errors.
Are there any optional fields in the 802.11b PPDU?
The preamble can be long or short; short preamble is optional and used for better efficiency.
What role does the PLCP header play in rate adaptation?
It signals the data rate so the receiver can correctly demodulate the incoming signal.
Can 802.11b PPDU support simultaneous data rates?
No, each PPDU is transmitted at a single data rate specified in the PLCP header.
How does the PPDU structure affect wireless throughput?
Longer preambles increase overhead, reducing throughput, whereas short preambles improve efficiency.
Is the 802.11b PPDU compatible with other 802.11 standards?
The PPDU structure differs from 802.11a/g/n due to different modulation and PHY layer characteristics.
What physical layer coding does 802.11b use in the PPDU?
Uses Barker code spreading for 1 and 2 Mbps, and CCK for 5.5 and 11 Mbps rates.
How does the PPDU relate to overall 802.11b frame transmission?
The PPDU encapsulates MAC frames for physical transmission over the wireless medium.
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