以波束成型為基礎之第五代行動通訊與第六代WiFi網路共存系統設計

Beamformer-Based Co-existence System Design for 5G NR-U and WiFi-6 Networks

李嘉恆(Chia-Heng Lee)

指導教授 ： 闕志達

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103583

摘要

隨著科技的進步以及時代的演進，近年來大眾對於無線連網裝置的依賴程度越來越高，除了單位時間內所需的資料傳輸速率提高以外，在同一時間內連網的裝置數量也越來越多。而在傳統的無線通訊系統中，不同使用者的資料通常是利用時間或是頻率的分隔來達到多重接取的效果，例如時間分工多重接取(TDMA)、頻率分工多重接取(FDMA)，以及正交分頻多重接取(OFDMA)。但礙於同一個時間內無線通訊頻譜的總量是有限的，所以若連網裝置的數量持續增加，勢必會遇到物理資源不敷使用的情況。因此也就必須利用其他類型的多重接取，例如：空間分工多重接取(Spatial Division Multiple Access, SDMA)將不同使用者所傳送的資料分隔開來。而在2020年年初FEC的規畫中，公布了在6GHz頻段做為未授權頻段，為了使用此頻段，5G NR就必須要和其他未授權技術共用，稱為NR-U。而本論文中針對於WiFi與5G的共用使用多使用者多輸入多輸出波束成型技術(Multi-User MIMO Beamforming)，以MVDR波數成型為基礎，開發出具置零之多使用者的波束成型技術(MUN)。
在本論文的第二章中，介紹了MVDR演算法做為接收端的波束成型技術，同時提出該如何將此波束成型轉換為發射端的公式，而根據波束成型轉換為發射端的公式，可以提出多使用者波束成型(MU)演算法，同時介紹目前現有的兩大NR-U技術，Anchored NR-U與Standalone NR-U，同時說明相較於目前的NR-U技術，使用波束成型技術有什麼優點。
在第三章中，我們介紹了一種全新的通道，稱為多輸入多輸出散射通道(Scattering MIMO Channel)，同時設定了5G與WiFi的情境，從簡單至困難分別為情境A、情境B與情境C。最後針對前面提到的將多使用者演算法，改進為具置零之使用者波束成型(MUN)演算法，同時將此演算法運用於三種情境，證明此演算法的功能。
在第四章與第五章中，更加針對於實際情境，將原本的MUN演算法從接近於理想的情況，以偵測環境的方式做調整，開發出估計式具置零之使用者波束成型(MUN-SE)，和強健式具置零之使用者波束成型(RMUN)，並將此兩種方法運用於我們提出來的三種情境。為了加以驗證我們提出的演算法效能，我們使用不同的雜訊訊號比例來模擬不同的情境，最後還將5G接收機與WiFi接收機的位置均設定為隨機，以此證明我們的演算法效能是優於傳統演算法的。比起單純使用多使用者的NR，也就是非RMUN的情況下，在5G表現下降50%以下的情況下，WiFi最多能有743%的提升。

關鍵字

MVDR波束成型 ； 多使用者波束成型 (MU) ； 具置零之使用者波束成型 之使用者波束成型 (MUN) ； 估計式具置零之使用者波束成型 (MUN-SE) ； 強健式具置零之使用者波束成型 (RMUN) ； 頻譜效率 (Spectral Efficiency) ； 雜訊號比率 (ISR)

並列摘要

With the advancement of technology and the evolution of the times, the public has become increasingly dependent on wireless networking devices in recent years. In addition to the increase in the data transmission rate required per unit time, the number of devices connected to the Internet at the same time has also increased. More and more. In the traditional wireless communication system, the data of different users are usually separated by time or frequency to achieve the effect of multiple access, such as time division multiple access (TDMA), frequency division multiple access (FDMA), And orthogonal frequency division multiple access (OFDMA). However, since the total amount of wireless communication spectrum is limited simultaneously if the number of connected devices increases, physical resources will inevitably be insufficient. Therefore, other types of multiple access must be used, such as Spatial Division Multiple Access (SDMA), to separate the data sent by different users. In the FEC plan at the beginning of 2020, it announced that the 6GHz band was unlicensed. To use this band, 5G NR must share with other unlicensed technologies, called NR-U. In this paper, the Multi-User MIMO Beamforming technology (Multi-User MIMO Beamforming) is used. To share WiFi and 5G, based on MVDR beamforming, multi-user beamform with nulling (MUN) is developed.
In the second chapter of this paper, the MVDR algorithm is originally introduced as the beamforming technology at the receiving end. The formula for converting this beamforming to the transmitting end is proposed. According to the formula for converting the beamforming to the transmitting end, multi-user beamform (MU) can be proposed. We also introduce the two existing NR-U technologies, Anchored NR-U and Standalone NR-U, and explains the advantages of using beamforming technology compared to the current NR-U technology.
In Chapter 3, we introduced a channel called Scattering MIMO Channel. At the same time, we set 5G and WiFi scenarios. From simple to complicated, they are Scenario A, Scenario B, and Scenario C. Finally, the aforementioned beamforming algorithm is improved to a multi-user beamform with nulling algorithm (MUN). At the same time, this algorithm is applied to three scenarios to prove the function.
In Chapters 4 and 5, more specific to the actual situation, the original MUN algorithm is adjusted from the ideal position to detecting the environment. The multi-user beamforming with nulling and STA angle estimation (MUN-SE) and robust multi-user beamforming with nulling (RMUN) are developed. We then apply these two methods to the three proposed scenarios. To verify the performance of our proposed algorithm, we use different signal-to-noise ratios in different scenarios and use different interference-to-signal ratios. Finally, we set the positions of both the 5G receiver and the WiFi receiver to be random to prove that the performance of our algorithm is better than traditional algorithms. Compared with the no-RMUN system with severe NR interference, the WiFi spectrum efficiency coexisting with the RMUN NR-U system is up by 743%, while the NR-U performance degrades by less than 50%.

並列關鍵字

MVDR BF Design ； Multi-User BF Design (MU) ； Multi-User BF with Nulling (MUN) ； Multi-User BF with Nulling and STA Angle Estimation (MUN-SE) ； Robust Multi-User BF with Nulling (RMUN) ； Spectral Efficiency (SE) ； Interference to Signal Ratio (ISR)

參考文獻

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