Wireless Phy in ns-3

The goal of this project is to define a common interface to a set of PHY-level models for wireless transmission mediums spanning a large range of wireless transmission systems:

• 802.11a/b/g
• wimax
• satellite
• ...

The following sections try to define:

• the characteristics of each wireless transmission system we want to capture
• various models to capture these characteristics

802.11a/b/g

characteristics:

• carrier frequency: b/g: 2.4GHz, a: 5GHz
• signal spread: 20Hz
• 802.11b transmission modes:
  • 1Mb/s: DBPSK + barker PN sequence
  • 2Mb/s: DQPSK + barker PN sequence
  • 5.5Mb/s: CCK + code spread
  • 11Mb/s: CCK + code spread
• 802.11a transmission modes:
  • 6Mb/s: BPSK + FEC 1/2
  • 9Mb/s: BPSK + FEC 3/4
  • 12Mb/s: DBPSK + FEC 1/2
  • 18Mb/s: DBPSK + FEC 3/4
  • 24Mb/s: QAM16 + FEC 1/2
  • 36Mb/s: QAM16 + FEC 3/4
  • 48Mb/s: QAM64 + FEC 2/3
  • 54Mb/s: QAM64 + FEC 3/4

The MAC layer needs modelization of the following features:

• interference among multiple stations transmitting at the same time
• resistance of different transmission modes to interference: the 54Mbs mode should resits less than the 6Mbs mode
• signal propagation: attenuation and delay

So, a typical PHY would be caracterized by one of 5 states:

• TX: transmitting some bits
• SYNC: receiving some bits
• IDLE: not doing anything, medium is not busy
• BUSY: not doing anything, medium is busy
• SLEEP: sleeping, not listening to the medium for status

The condition for BUSY state is precisely defined for 802.11: it is called CCA state detection. There are multiple CCA modes but the basic mode is based on the total energy measured at the antenna.

Notes:

• some people might need multiple SLEEP states: some SLEEP states are deeper than others, take longer to recover from, etc.
• some people want to modelize antenna directionality. I have zero idea on how to modelize this.

Models which fulfill these needs:

• yans