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Zhangqin Huang

Zhangqin Huang. Behavioural and Performance Modelling of a Digital Enhanced Cordless Telecommunications (DECT) System. Problem: Problem description Requirements National Semiconductor’s SC14428 chipset Project Goals Related Work & Results DECT protocol stack DECT double slot frame

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Zhangqin Huang

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  1. Zhangqin Huang Behavioural and Performance Modelling of a Digital Enhanced Cordless Telecommunications (DECT) System DECT System

  2. Problem: Problem description Requirements National Semiconductor’s SC14428 chipset Project Goals Related Work & Results DECT protocol stack DECT double slot frame POOSL system level model Validation The next step Contents: DECT System

  3. DECT wireless PTn …... PT4 PT3 PT2 PT1 Class room …… FP1 FPm FP2 Speech Mixer Central Unit Problem: A Class Room with High Capacity Speech DECT System • Background: • Class room • 1 teacher and 3-11 deaf children • Communication each other • Voice should be very clear • 3 layers (PT’s, FP’s and Speech Mixer) • Problems: • How to design this DECT system? • How many PT’s (n) can be supported by one FP? How many FP’s (m) do we need? • How powerful Speech Mixer do we need? DECT System

  4. The speech bandwidth should be at all frequencies in the range of 200Hz to 8 kHz (normal standard < 3.2kHz) The number of PT’s is between 4 and 12 The central unit receives and mixes the speech signals from the all PT’s in the same location; then the speech signals being mixed will be broadcasted to all PT’s The speech delay should be less than 20 ms National Semiconductor’s recent SC14428 chipset Requirements DECT System

  5. The Difference between Normal Telephony and Our Case High speed CODEC (80 kbps) Use SC14428 Multi Function Baseband to build PT or FP PT’s: use 1 high speed CODEC FP’s: (1,2 or 3?) investigate how many high speed CODEC data can be computed by one CR16? * From National Semiconductor Corporation Integrated normal CODEC (32 kbps) Co-processor DIP for DECT frame structure Microprocessor CR16 DECT System

  6. Create a behavioural model of the DECT protocol, investigate how the messages, frames, bearers, MAC-packets and physical packets work through the different layers in DECT system; learn a lot about DECT system from this model. How many links can be supported by one FP (SC14428 chipset) using P80 physical channel? How many FP’s in the central unit do we need if we want to support 11 deaf children with 1 teacher to communicate each other? Investigate the required speech Mixer capacity; Project Goals DECT System

  7. DECT Protocol Stack Application: Capture, transmit & Receive, play the speech data Network: Call setup / release Speech data transfer Data Link: Frame segmentation, fragmentation, recombination, assembly Link setup / release Fragments buffering MAC: MAC-connection setup / release Multi-bearer setup / release * Beacon broadcast Physical: Packets receive & transmit In our case we only need implement a part of DECT protocol DECT System

  8. Double Slot Frame in DECT protocol NWK layer Speech data Message DLC layer … Frame … 100 octets 100 octets 1 PDU 1 PDU A-field B-field X MAC layer 8 40 16 800 4 H Tail RA PHY packet 80 (P80) PHY layer GS=56 16 16 64 804 4 S field D-field Z field Uplink Downlink G 0 G 1 G 2 G 3 G 4 G 5 G 6 G 7 G 8 G 9 G 10 G 11 1 frame (10 ms) = 6 double slots • In our case we should use double slot frame (P80) because we use high speed CODEC; but in normal telephony they use single slot frame (P32); it is very different for performance, e.g. speech delay, buffer occupancy. • Implementation of DECT system using P80 is not often. • This picture is about the bit information in different layers. We should check the bits correct or not in POOSL model. DECT System

  9. POOSL System Level Model (1) a) One cell DECT system b) One portable part • One application process (Mixer) • One DECT protocol cluster in fixed part • Multi portable parts • Air channels • Message channels (CC, MM, speech) • One application process (CODEC) • One DECT protocol cluster in portable part • One air channel • Message channels (CC,MM,speech) DECT System

  10. POOSL System Level Model (2) c) DECT protocol stack DECT protocol stack structure is same as before d) high MAC layer and low MAC layer DECT System

  11. Validation (1) for Messages in Network Layer FP App Fixed part NWK Portable part NWK PP App Primitives NWK Messages NWK Primitives NWK {MNCC_SETUP} MNCC_SETUP-ind MNCC_SETUP-req {MNCC_SETUP_ACK} MNCC_SETUP-ACK-ind MNCC_SETUP-ACK-req {MNCC_CONNECT} MNCC_CONNECT-ind MNCC_CONNECT-req b) Standard specification for messages in network layer a) Simulation results from POOSL model DECT System

  12. Validation (2) for MAC-Connection Setup Application Application MNCC_SETUP-req MNCC_SETUP-ind NWK NWK DL_ESTABLISH-req DL_ESTABLISH-ind DL_ESTABLISH-cfm DLC DLC MAC_CON-req MAC_CON-ind MAC_CON-cfm MAC MAC PL_TX-req PL_TX-req PL_RX-cfm PL_RX-cfm Packet PHY PHY b) Standard specification for MAC-connection setup in DECT protocol a) Simulation results from POOSL model (more detail) DECT System

  13. Little refinements of model / reporting; Project goal 2: investigating how many links can be supported by one FP and how many FP’s in the central unit we need; Project goal 3: investigating how powerful required Mixer capacity we need. The Next Step DECT System

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