Alvarion BreezeNET PRO.11 Guía de usuario Pagina 194

  • Descarga
  • Añadir a mis manuales
  • Imprimir
  • Pagina
    / 209
  • Tabla de contenidos
  • SOLUCIÓN DE PROBLEMAS
  • MARCADORES
  • Valorado. / 5. Basado en revisión del cliente
Vista de pagina 193
Appendix
User’s Guide 9-38 BreezeNET PRO.11 Series
9.5.9 Frame Formats
All 802.11 frames are composed of the following components:
Preamble PLCP Header MAC Data CRC
9.5.9.1 Preamble
This is PHY dependent, and includes:
Synch: An 80-bit sequence of alternating zeros and ones, which is used by the
PHY circuitry to select the appropriate antenna (if diversity is used), and to
reach steady-state frequency offset correction and synchronization with the
received packet timing.
SFD: A Start Frame delimiter which consists of the 16-bit binary pattern 0000
1100 1011 1101, which is used to define frame timing.
9.5.9.2 PLCP Header
The PLCP Header is always transmitted at 1 Mbit/s and contains Logical
information used by the PHY Layer to decode the frame. It consists of:
PLCP_PDU Length Word: which represents the number of bytes contained in
the packet. This is useful for the PHY to correctly detect the end of packet.
PLCP Signaling Field: which currently contains only the rate information,
encoded in 0.5 Mbps increments from 1 Mbit/s to 4.5 Mbit/s.
Header Error Check Field: Which is a 16 Bit CRC error detection field.
Vista de pagina 193
1 2 ... 189 190 191 192 193 194 195 196 197 198 199 ... 208 209

Comentarios a estos manuales

Sin comentarios