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

4-June-07 P1901_PRO_016_r0
PAP Info Bits Parameter Description
[2] Polarity of the left-over bits The PAP Information per
group is about a number of
packet ids. The rest of packet
ids are correctly received if
“polarity of the left-over bits”
is equal to 1. And incorrectly
received if it is equal to 0.
[8:3] Compression Ratio Number of packets
represented by each bit
Table 15: PAP algorithm information
The difference between Algorithm A, B and C is that B and C needs extra information.
In case of Burst with data, the bits in Burst Header are used depending on the chosen algorithm:
- Algorithm A, the bits from [54:9] are used to describe the status of each group (Group Status)
- Algorithm B and C:
o Bits from [19:9] are used for parameter “offset”.
o Bits from [54:20] are used to describe the status of each group (Group Status)
In case of Burst without data, the bits in Burst Header are used depending on the chosen algorithm:
- Algorithm A, the bits from [118:9] are used to describe the status of each group
- Algorithm B and C:
o Bits from [19:9] are used for parameter “offset”.
o Bits from [118:20] are used to describe the status of each group (Group Status)
5.4.2.1 Group Encoding: Algorithm A
In this algorithm the receiver shall send 4 pieces of information to the transmitter.
1. The last correctly received packet
2. The number of packets in each group (compression ratio)
3. The polarity of the left-over bits (1 shall mean received correctly/ 0 shall mean received incorrectly)
4. The PAP coded bit: 46 bits in Burst Header with data or 111 bits in Burst Header without data.
With this information the transmitter shall be able to reconstruct the receiver window and retransmit or free-up
packets appropriately.
The PAP informatioin decoder (transmitter) in order to reconstruct the status of the packets sent previously to the
last correctly received shall take the first bit of the coded bits and replicate it a number of times, (given by the
Submission page 159 UPA-OPERA