Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
compression ratio), until completing the window (2048 bits). The group porder goes from the most recently
received to least recently received (see Figure 60)
Polarity
of lefover
bits
PAP
Coded
Bits
[last bit]
Compression
ratio
2048
5.4.2.2 Packet ACK Protocol: Algorithm B
PAP
Coded
Bits [1]
Figure 60: Packet ACK Protocol: Algorithm A
Last correctly
received packet
PAP
Coded
Bits [0]
Submission page 160 UPA-OPERA
ok
Compression
ratio
Compression
ratio
This algorithm is similar to the algorithm A but one extra piece of information shall be sent:
• An offset that shall indicate where the next transition (status change) after the last correctly received packet
(not including the offset itself) occurs.
In this algorithm, the status of the groups is described by 35 bits in Burst Header with data or 99 bits in Burst
Header without data.
With this information the PAP decoder (transmitter) shall take the previous packet to the last correctly received
packet, and count backwards until the offset is reached and. It shall fill these spacespositions with either ones or
zeros (depending on the polarity bit). After this, the decoding of the algorithm B shall be identical of that ofto the
algorithm A. The process is described in the following figure:
Polarity
of lefover
bits
PAP
Coded
Bits
[last bit]
Compression
ratio
2048
PAP
Coded
Bits [1]
PAP
Coded
Bits [0]
Compression
ratio
Compression
ratio
Figure 61: Packet ACK Protocol: Algorithm B
1
Last correctly
received packet
NOT
PAP
Coded
Bits [0]
Offset
ok
1