Time Flow

. The most important part in the server model is the control of time flow. The system is easier to be crashed without having a correct time stamp. To make our system operate correctly, we provide a time flow for the process of MAC shown in Figure 5-13.

The sketch map in Figure 5-13 is divided into two parts with UL sub frame and DL sub frame. During the interval of uplink, the BS starts to receive the bursts and CDMA codes from each SS. At the same time, the BS starts to deal with the UL_Scheduler and the DL_Scheduler making UL_MAP, DL_MAP and bursts to transmit the broadcast bursts at the start time of the downlink. During the interval of downlink, the BS starts to broadcast to all SSs and process the bursts receiving at the uplink. In the mean while, the BS also deals with the Deconcatenation, Message_Managemenet and Control_Mechanism to analyze, response and produce correspond message to all SSs at the start time of downlink. The time stamp of Assembler and Classifier do not need the exact time due to the process controlled by upper layer or by the process of DL_Scheduler.

With the time flow we proposed, the system could operate smoothly.

Figure 5-13 Time Flow

CHAPTER 6 CONCLUSION

6.1 Conclusion

In this thesis, we provide a design flow, which is different from the traditional design flow. At first, we analyze the specification of WiMAX MAC and construct the architecture of MAC. And then we translate the protocol into server model using SDL.

Finally, we translate SDL into C model and using the system synthesis to reduces our design effort in system level designs.

With the implementation of WiMAX MAC, we point out some issues of transmission behaviors in wireless environment and provide the solutions to simplify the verification environment.

From different protocols in wireless communication, we find some properties, which have the same in architecture design. To modulize the architecture of MAC, we analyze the basic functionalities of the data plane and control plane. For the requirement of implementation, we integrate some components to a specific module and provide the protocol architecture of WiMAX MAC BS.

We utilize the concept of the server model to translate the architecture from protocol to SDL model. With some characteristics of the server model, we modify the priority of each task and optimize the timers and data structure in a wireless communication system. Finally, we show the message flow and the time flow to guarantee the system can be operated correctly.

6.2 Future Work

Although we provide a design methodology of communication system, we still have some tasks that have not finished. From our implementation, we need to complete the advance MAC functionalities defined in WiMAX and need to construct full functions of SSs to verify the functionalities of the system. After that, we could analyze the performance of the system and enhance the system performance by ESL-based hardware/software partition according to the constraints and requirements of WiMAX MAC.

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