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POCSAG System Capacity Analysis
Signaling Speed: 512 bps 1,200 bps 2,400 bps POCSAG Coding Format
Preamble Length: 1.1250 sec 0.4800 sec 0.2400 sec A preamble contains 576 bits
Assumed to be sent 1 time                  
for each 30 batches                  
Batch Length: 1.0625 sec 0.4533333 sec 0.2266667 sec 1 batch = 1 sync codeword plus 8 frames (2 codewords each frame) =17 codewords
Fully Loaded Paging event with 30 Batches: 33.00 sec 14.08 sec 7.04 sec preamble length + 30 X batch length
The number of available events in a 1 hour period                  
with 30 batches per                  
event =   109   256   511        
At 8 frames                  
available per batch                    
and 2 codewords                  
in each frame, there are: 16   16   16   codewords per batch
      480   480   480   codewords per 30 batch event
      52,320   122,880   245,280   codewords available per hour
From an efficiency stand point, in the System Capacity calculations that follow only 90% of the available codewords will be considered available.
Hence, a 512 POCSAG System provides 47,088 codewords per hour.      
  1,200 POCSAG System provides 110,592 codewords per hour.      
  2,400 POCSAG System provides 220,752 codewords per hour.      

 

Address and Messaging Structure and Calls per User Hour Influence:
Page Structure Address + Message Codewords Required   Expected Peak Call Rate per User Hour Effective Codewords
Tone 1 + 0 = 1 0.15 0.15
Numeric 10 digit 1 + 2 = 3 * 0.25 0.75
Alphanumeric 40 Char 1 + 14 = 15 ** 0.30 4.50
10% T, 70% N10, 20% A40 = 1, 3, 15 0.15, 0.25, 0.30 1.44
System Capacity = Number of Codewords available per Hour ÷ Effective Codewords Required
System Structure Effective Codewords Required 512 bps POCSAG Number of Users @ Efficiency below 1,200 bps POCSAG Number of Users @ Efficiency below 2,400 bps POCSAG Number of Users @ Efficiency below
100% Tone 0.15 313,920 735,750 1,471,500
100% Numeric 10 digit 0.75 62,784 147,150 294,300
100% Alphanumeric 40 char 4.50 10,464 24,525 49,050
10% T, 70% N10, 20% A40 1.44 32,700 76,641 153,281
      Efficiency: 90% Efficiency: 90% Efficiency: 90%
* A Numeric digit requires 4 bits; with the (32,21) codeword    
  20 bits are available for messaging -- this yields 5 digits per codeword    
  2 codewords are required for 10 digits    
** An Alphanumeric character requires 7 bits; with the (32,21) codeword    
  20 bits are available for messaging -- this yields 2 6/7 characters per codeword    
  14 codewords are required for 40 characters    
END OF SECTION
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