Specifications

2010-10-26 Network Design and Engineering Guide 63
General Carrier Design
TDMA Carrier Design with ’TDMA Calculator’
Table 2-5 Summary ’General Data Output’ Parameter
2.6.4 Area ’Data output per frequency channel’
The following carrier specific parameters are displayed in this section:
- User data rate ’User data rate [kbit/s]’, symbol rate ’Symbol rate [kBaud]’ and frequency
bandwidth per carrier ’Frequency bandwidth [kHz]’. This is the main result of the calcula-
tion, as it determines how much data rate is available on this channel for IP and Frame Re-
lay based applications and as result how much space segment must be leased on the
satellite transponder.
- Calculated minimal signal to noise ratio ’Eb/No [dB]’ and ’Es/No [dB]’ for the given modu-
lation and coding.
Channel TDMA structure parameter: ’Data slot length [base slots]’, length of the request subframe ’Length rqst. frame [time slots]’, length of the reference burst subframe ’Length ref. slot [time slots]’, channel gross container size ’Length gross container [byte]’, data slots ’Data slots per TDMA frame’ and total time slots per TDMA frame ’Data rate per slot ass.[bit/s]’ .
- The spectral efficiency values per carrier ’Efficiency [bit/symbol]’ and ’Efficiency [bit/s/Hz]’.
Length base gross container
[byte]
Displays the size of the base gross container of channel 1 with data
slot length = 1, optimized for the specified traffic.
Traffic is sent over satellite in coded gross container packages. A
base gross container holds the traffic data plus some overhead (e.g.
TDMA header, SLL header, signalling bursts ) before adding the For-
ward Error Correction (FEC) bits.
Time base slot Displays optimized TDMA base slot time of the network in microsec-
onds.
Number request slots per
base slot
Displays quantity of request slots that could be placed in one base
data slot.
Total user data rate [kbit/s] Displays calculated available data rate for the user applications for all
channels.
User data rate per channel is derived as input from the traffic capacity
calculation.
Total frequency bandwidth
[kHz]
Displays total space segment size. Summary of all symbol rates x
spacing factor of all channels
Total efficiency [bit/symbol] Displays the average efficiency of all channels :
Efficiency = user data rate / symbol rate.
Total efficiency [bit/s/Hz] Displays the average efficiency of all channel:
Efficiency = user data rate / frequency bandwidth.
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Current SkyWAN
®
software supports up to 256 time slots per TDMA frame.
If this number is exceeded on any carrier, the solution is invalid and no out-
put results are given.
An error message is displayed either in the stand-alone ’TDMA Calculator’
status line or in the ’SkyNMS Network Configurator’ Output window.
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If the request burst length is larger than one, additional user capacity may
be generated by increasing the superframe size.
Parameter Name Definition