# Presentation: 391486

## HDLC Framing Study

**Data/Results**
**Rick Schnurr/Code 560.0**

**hdlc_results_rgs_12_10_01.ppt**

## HDLC Link study completed for un-coded and convolutional coded TDRS channels.
Data derived from digital simulations
Random data used in simulation
Work Performed by ITT-AES lead by Mark Burns and John Wesdock
Data summarized in the following charts

**Data derived from digital simulations**
**Random data used in simulation**
**Work Performed by ITT-AES lead by Mark Burns and John Wesdock**
**Data summarized in the following charts**

**HDLC Link Study**

## HDLC outperforms CCSDS at high BER (ie 10-5)
CCSDS outperforms HDLC at low BER (ie 10-6)
HDLC has additional overhead,  see inset on plots
CCSDS advantage at low BER is explained by reduced overhead
Additional HDLC packet frame and CRC explains its better performance at higher BER.
HDLC framing mechanism is certainly usable and might be preferred if one is using a link with high BER (ie 10-5)
Higher MTU would be nice for lower BER HDLC links.  HDLC packets limited to standard 1500 byte IEEE 802.3 max MTU
Bit stuffing overhead is unavoidable but low for HDLC
Recommend avoiding data with long strings of ones for HDLC
Planning to run case with all flag bits to see if TDRS receivers have any issues – not completed yet
Don’t need to run R/S case – can extrapolate from what we have
Simulation software is available if a mission needs the data

**CCSDS outperforms HDLC at low BER (ie 10-6)**
**HDLC has additional overhead,  see inset on plots**
**CCSDS advantage at low BER is explained by reduced overhead**
**Additional HDLC packet frame and CRC explains its better performance at higher BER.**
**HDLC framing mechanism is certainly usable and might be preferred if one is using a link with high BER (ie 10-5)**
**Higher MTU would be nice for lower BER HDLC links.  HDLC packets limited to standard 1500 byte IEEE 802.3 max MTU**
**Bit stuffing overhead is unavoidable but low for HDLC**
**Recommend avoiding data with long strings of ones for HDLC**
**Planning to run case with all flag bits to see if TDRS receivers have any issues – not completed yet**
**Don’t need to run R/S case – can extrapolate from what we have**
**Simulation software is available if a mission needs the data**

**Conclusions**

## True cost study to examine the cost implications of HDLC
Both SN and GN “factories” should be included
Final decision by Agency

**Both SN and GN “factories” should be included**
**Final decision by Agency**

**Next Step**

## Frame Error Rate vs Channel BERUncoded Service

## Packet Error Rate vs Channel BERUncoded Service

## Throughput vs Channel BERUncoded Service

## Frame Error Rate vs Channel BERConvolutionally Coded Service

## Packet Error Rate vs Channel BERConvolutionally Coded Service

## Throughput vs Channel BERConvolutionally Coded Service

## Throughput Definition

**Ground Station**

**Space-to-Ground****Link**

**TDRS**

**Space-to-Space****Link**

**User Satellite**

**IP Packet****Generator**

**Data****Framer****(CCSDS****or****HDLC)**

**R-S****Encoder*******

**Convolutional****Encoder**

**Transmitter****Physical****Layer****Components**

- ScienceData

- ThermalNoise

**Relay Sat****Physical****Layer****Components**

- ThermalNoise

**Receiver****Physical****Layer****Components**

**Viterbi****Decoder**

**R-S****Decoder**

**HDLC****Frame****Reader**

**CCSDS****Frame****Reader**

**Total bits****transmitted****counted**

**De-Packetizer****(Science Data****Extraction)**

**Correct Science****bits counted**

**                         ****Science bits received correctly**
**Throughput = ********——******
**                                 ****Total bits transmitted**