Generic mac
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This document presents a generic framework for expediting the development of Layer 2 MAC protocols. The framework includes common functionalities, a system model based on multithreaded modules, and a state handler matrix. It provides network and physical layer abstraction, a common library, and an OSAL. The framework reduces MAC development time by 40% and was used to implement a WMAN MAC. The roadmap includes packaging the framework as a wizard and enriching the library with new functions.
Generic mac
- 1. 1. Generic Framework Architecture For Expediting Development of Layer 2 MACs Soma Bandyopadhyay Convergence Solutions Practice TATA Consultancy Services Limited, Kolkata
- 2. 2. Introduction Features Common functionalities System model System Architecture Thread module Core-MAC State Handler matrix MAC-SAP-Interface PHY-SAP-Interface Library OSAL Case study -WMAN MAC implementation on generic MAC framework Achievements Road-Map AGENDA
- 3. 3. Introduction Generic MAC development framework - Can be used as basic development framework for any Media Access Control (MAC) /(Layer 2) protocol. Reduces the development time for any MAC stack development Specific definition for specific MAC needs to be added mostly in the header files and the existing data structure needs to be updated accordingly.
- 4. 4. Generic software architecture for developing any type of MAC Network and physical layer abstraction modules. A common library- exposes different generic application programming interface (API). Unique Macros (pre-processor definitions used in C programming language) to route to different state handlers based on the current state and incoming event as defined in the two-dimensional state-event matrix. This framework ensures towards the faster development of MAC stack, thereby reducing the time-to-market. Salient Aspects
- 5. 5. Common Functionalities Specific MAC Routing to state handlers OSAL-Operating system adaptation layer PHY Abstraction module Common library Message Parsing Message generation State handlers Specific MAC functionalities Generic MAC features common to all MAC MAC framework Inputs to framework
- 6. 6. System Model Based on a multithreaded structure Specific MAC definitions are mostly defined in header files Thread modules :Generated by the initialization function MAC-SAP-Interface –Provides Layer3(Network Layer) abstraction Core-MAC- Provides main state-machine implementation, Synchronization with other thread modules and PHY Collects the definition for the specific MAC from the header files PHY-SAP–Interface -Provides Layer1(Phy Layer) abstraction Thread modules can generate further threads Library –Provides all the basic functionalities OSAL(Operating System Adaptation Layer)- Encapsulates all the system calls
- 7. 7. System Architecture Core MACFramework() -Initialization function Library OSAL Device Driver MAC SAP Interface PHY-SAP Interface Physical Layer
- 8. 8. Thread Modules – Core-MAC Core-MAC- Main control module of the MAC Keeps track of the current state Keeps synchronization with all the thread modules Routes to state-handlers in the state-event handler matrix by using a Macro current state and the event occurrence number are used as inputs to the Macro Triggers the output event corresponding to the current state and the event occurrence number to the destination Generates own Service Data Unit (SDU) from the higher layer Protocol Data Unit (PDU) Decodes/Parse the incoming event Initiates the data path Manages MIB & Authentication
- 9. 9. State Handler Matrix Callback State0_Event0 () Struct output-event- Output event-id Destination- id Callback State1_Event0() Struct output-event- Output event-id Destination- id Callback State2_Event0() Struct output-event- Output event-id Destination- id Callback State0_Event1() Struct output-event- Output event-id Destination- id Callback State1_Event1() Struct output-event- Output event-id Destination- id Callback State2_Event1() Struct output-event- Output event-id Destination- id Callback State0_Event2() Struct output-event- Output event-id Destination- id Callback State1_Event2() Struct output-event- Output event-id Destination- id Callback State2_Event2() Struct output-event- Output event-id Destination- id State State0 State1 State2 Events Event0 Event1 Event2 Implemented as a two dimensional array of structure Looked up by current state and row id
- 10. 10. Thread Modules – MAC-SAP-Interface Layer 3 MAC-SAP- Interface Capture thread Core-MAC SDU Trigger data capture /Send data to layer 3 Buffers , classifies packet Uses library calls Packet Packet Reconstructs , sends packet to layer 3, Uses library calls Reconstruct thread
- 11. 11. Thread Modules – PHY-SAP-Interface Layer 1/PHY PHY-SAP- Interface Receive thread PHY-SAP-MIB thread Core-MAC SDU Trigger data capture /Send data to layer 3 Buffers , Receives packet, Checks whether PHY is dead or alive. Uses library calls MIB-Info Packet Keeps track of PHY-MIB data , Uses library calls Send function is encapsulated within Library function , it is considered as a non blocking function and no thread is generated for it.
- 12. 12. Library- Makes available the basic functionalities by exposing different generic Application Programming Interface (API). Protocol-specific functionalities can be added to these APIs. Main APIS: Message receive & Send to the peer MAC and its own threads MAC Protocol Data Unit (PDU)(payload+header) generation Fragment & defragment PDU Classify & Reconstruct packet Parsing/decode message Determination of message identifier Uses the OSAL to access any System Call Library
- 13. 13. OSAL- Provides an adaptation layer on top of the operating systems Establishs a path between the MAC and the device driver of the physical layer device Wraps all the Inter Process Communication (IPCs) (like message queue operations, semaphores for mutual exclusion, event synchronization, and timer handlers etc.) OSAL –Operating System Adaptation Layer
- 14. 14. Case Study –WMAN MAC On Generic Framework ClassifierMAC-SAP Interface thread (Convergence sub- layer) Core MAC (Common Part Sub-Layer) PHY-Manager Receive Re-constructor PHY- MIB SFID, QOS, CID Message queue OSAL Library PHY Device Driver PHY -OFDM PHY_ SAP
- 15. 15. Case Study –WMAN MAC On Generic Framework Contd. Wireless Metropolitan Area Network (WMAN) MAC stack development is going on based on generic MAC framework Joint partnership project is already signed up with CDOT Objective : Indigenous WiMAX product development To provide high-speed wireless Internet access to rural as well as urban areas TCS will provide the Platform independent MAC for Base Station & Service Station Target hardware with RF & PHY block will be provided by CDOT TCS will port the platform independent MAC on CDOT board Finally WMAN stack will be integrated with MAC for Milton as Customer Premises Equipment CPE)/Service Station.
- 16. 16. Achievements Reduction in MAC development time –40% approx. Eases the porting activity Adaptation of different layer 3(network-layer) data traffic Adaptation of different PHY (Physical layer)
- 17. 17. Road-Map Packaging of the framework as a Wizard Used as a tool to perform some of the work in an automated way Creates the source files for the framework Take the Specific MAC definition as Inputs Enriching library by adding following functionalities Authentication Packing & Unpacking of packet Padding
- 18. 18. Thank You
- 19. 19. OSAL –Operating System Adaptation Layer MIB- Management Interface Base WiMAX- Worldwide Interoperability Microwave Access SFID –Service Flow identifier QOS- Quality of Service CID –Connection identifier Layer 3/L3 – Network layer Layer2 /L2 –MAC layer PHY- Physical Acronym