研究多數位訊號處理器架構的長期演進技術小型基站

Abstract

在現今社會中仍使用許多大型基站，基站間因為會互相干擾，彼此不能設太近，這會造成部分地區訊號不佳的問題，以及部分室內遮蔽物太多，或是地下室，也都有收訊不好的問題，使用小型基站可以解決以上問題，不只可以提升覆蓋率，還可以為大型基站分擔流量，而且架設成本、功耗也都比較低，我們可以在使用者數量龐大的地方佈建一些小型基站以分擔流量，像是鬧區、火車站，在辦公大樓中，由於遮蔽物太多，許多地方收訊不好，也很適合佈建小型基站來增加覆蓋率。 本篇論文實作了Single-Core架構及Dual-Core架構小型基站，並且可以通過LTE 5MHz頻寬下的壓力測試，測試資料量為一個frame，在Dual-Core架構的部分驗證了兩個DSP之間的控制與資料傳輸，以及匯流排擴充的測試，證明此架構是能夠Scale-up的，不增加匯流排數量最高可以擴充到16個DSP及16個硬體加速器，若增加匯流排則可以更多，效能評估的測試取LTE規格頻寬20MHz，硬體部分包含連續2048點的FFT/IFFT運算，及Turbo Decoder在modulation type 64-QAM，一個subframe有效資料最大情況，運算所需時間，軟體的部分參照DSP公司提供的數據， Uplink Flow與Downlink Flow的一個subframe資料皆可在1ms內處理完畢，符合LTE規格。

There are many base stations still exist in modern times. The distance between base station must not be close because it would cause some area have bad reception by interfering. Bad reception will also happened in the basement or shadowing. The problem described above can be solved by Small Cell. Small Cell are not only increase coverage but also share the flow with base stations, and the cost of power and set up are very low, so we can set up some Small Cell at the place where have huge number of users, like stations, office building, downtown etc. This paper shows the implementations of Single-Core Small Cell and Dual-Core Small Cell and it would pass the stress test in 5Mhz bandwidth of LTE. In the architecture of Dual-Core, we verify the control and data transfer between two DSP and bus extension test in a frame. We prove the architecture of Dual-Core can be scale-up. We can extend 16 DSP and 16 hardware accelerator by not increasing the number of bus. If we increase the number of bus, we can extend more DSP and hardware accelerator. We test the performance of our platform in 20Mhz bandwidth of LTE which contains the maximum number of data in a subframe. The Uplink flow and Downlink flow of our implementation can be done in one millisecond which is the time limit of a subframe in LTE standards.