無線新世代高速系統設計(I)

Abstract

對無線新世代高速系統設計而言，提供高速傳輸的服務品質控制是其主要的目的。 當傳輸速率超過十萬位元每秒，甚至千萬位元每秒，對於每一層的架構設計就必須改進 並演化。 在這個計畫中，我們著重在高速傳輸設計中的三個領域：（1）多重準則排程控制，（2） 可靠性快速傳輸，和（3）無線高速傳輸的關鍵要素。 排程控制被確認為在達成高速率傳輸上有重大貢獻，我們提出的多重準則的排程控制是 去克服在系統生產量和公平性和服務品質之間的權衡問題。藉由已定義目標的Pareto 最 佳化方法，可以根據任何效能上的制訂來解決多維的問題，以至於達到最終設計的目標。 為了達到可靠的高速傳輸並維持互動性的服務品質（interactive QoS），擁有全範圍 （full-scale）的端對端的控制是很關鍵的。通道毀損（channel impairment）是無線系統 中的自然特性，在這特性下，即使傳輸在高通道速率（high channel rate），使用者感受 （user-experienced）傳輸速率會大大的降低。而所提出應用在無線電連結控制（RLP）， 媒體存取控制（MAC）和傳送控制協定（TCP）上的適應性的控制可以實現高速和可靠 的傳輸基於使用者感受（user-experienced）。 找到並驗證建立高速無線系統的關鍵元素是相當重要的。那些關鍵元素的影響（甚至彼 此間的影響）將被研究和量化。為了達到高速傳輸，有少數關鍵元素已經知道是存在的， 像通道預測（channel estimation），使用者多樣性（user diversity），可變動的傳輸速率 （flexible rates），還有多槽傳輸（multi-slot transmission）。但在排程控制和在通道預測 中的錯誤修正技術裡也有內鑲的設計要素。大部分的都是專利性的解決方式。在這個計 畫中，我們將學習和探究在無線通訊系統上所有可能的關鍵元素並提供針對每個元素的 設計控制。

High-speed transmission with QoS (quality of service) controls is considered as the major target for next generation wireless system designs. When the transmission rate exceeds Mbps (106) or even hundreds Mbps, the designs or the architecture at different layers needs to be changed (even evolutionally). In this project, we focus on two major areas for high-speed transmission designs: (1) Multi-criterion scheduler control, (2) Fast reliable transmission, and (3) Finding the key elements for wireless high-speed transmission. The scheduler controls have been identified as the major contribution to the high transmission rate. Our proposed multi-criterion scheduler control is to resolve the tradeoff problem between the system throughput and the fairness and/or the QoS. This multi-dimension problem could be solved by an objective-defined Pareto Optimality based on any performance metric to meet the ultimate design goal. To achieve reliable high-speed transmission and to maintain an interactive QoS, it is critical to have a full-scale end-to-end control. With the channel impairment nature in a wireless system, the user-experienced transmission rate could be reduced substantially even a high channel rate is used. The proposed adaptive control on RLC (radio link control), MAC (Medium Access Control), and the TCP (transfer control protocol) mechanism is to realize the high and realizable user-experienced transmission. Combining the schedule control, the interactive QoS can be achieved. It is always critical if the basic elements for constructing a high-speed wireless system can be identified. The impacts from (and the interaction between) those basic elements will be investigated and quantified. To achieve high-speed transmission, there are a few existing known key elements which are channel estimation, user diversity, flexible rates, and multi-slot transmission. But there are also embedded design elements within the scheduler controls and the error correction techniques in the channel estimation. Most of them are proprietary solutions. In this project, we will study and explore the all possible basic elements in wireless communication systems and provide the design controls for each element.