長期演進技術下適用於多媒體路況回報系統之服務品質感知資源管理

Abstract

多媒體路況回報系統是現今一個新穎的無線車載網路應用；此系統可以藉由車用設備與感測器提供各種種類的交通路況資訊，並採用長期演進技術(LTE)來達到遠距傳輸和較好的移動性。儘管有如此的改善，此系統中的資源管理問題須被重視。現存的資源管理研究主要致力於維持通道品質與滿足非車載應用的服務品質(QoS)需求，但若要得到最多且完整的交通路況資訊，包含地理覆蓋率，一個更符合多媒體車載應用特性的資源管理方法是不可或缺的。 在本篇論文中，我們針對多媒體路況回報系統，提出一個適用於LTE環境的QoS感知資源管理方法，稱為QoS-MTRS。此方法的主要設計理念是將資源依照每筆交通路況資訊的重要價值來分配，並且將通道的可用性也加入考量，以確保傳輸的可行性。此演算法的目標是在一定的資源(例如無線電資源)限制下，提高交通路況資訊的多樣性、完整性和總價值。最後，我們實作一個包含LTE環境的模擬環境，以測試此演算法的效能。模擬的結果顯示出，若採用QoS-MTRS，在同一地區收到兩種以上路況資訊的機率比採用頻寬與QoS感知排程演算法(BQA)、貪婪演算法(Greedy)和先來先服務演算法(FCFS)高出65%、58%和48%，且可將路況資訊重複率平均減低一半。採用QoS-MTRS所獲得的路況資訊總價值比起BQA、Greedy和FCFS分別高出27%、18%和54%，且在車輛僅有20輛的情況下，採用本演算法依然能達到87%的地理覆蓋率。

The multimedia traffic report system is a new type of applications in wireless vehicular networks. This system can provide various kinds of traffic information, which are directly obtained from on-car sensors and devices via LTE. By leveraging LTE technologies, the system can support wide-range transmission and better mobility. Despite of these improvements, the resource management problem needs to be addressed as well. Existing resource management studies focus on channel quality or QoS requirements for non-vehicular applications. To get the most useful and complete traffic information, including location coverage, a proper resource management mechanism for multimedia vehicular applications is indispensable. In this paper, we propose a QoS-aware resource management mechanism for multimedia traffic report systems over LTE (QoS-MTRS). The main idea is to schedule resources according to the importance degree of each traffic data. Furthermore, we take channel availability into consideration to make sure that the transmission is feasible. The objective of QoS-MTRS is to improve the diversity, completeness and overall traffic data value under certain resource (e.g., radio or bandwidth) limitations. We provide a system-level simulation that includes an LTE network environment to evaluate our design. Simulation results show that by adopting QoS-MTRS, the probability of receiving more than one kind of traffic data in a location is 65%, 58% and 48% higher than BQA (bandwidth and QoS-aware scheduler), Greedy and FCFS, respectively; the duplication ratio can be decreased by 50% on average. In terms of the overall traffic data value, QoS-MTRS is 27%, 18% and 54% higher than BQA, Greedy and FCFS. In addition, QoS-MTRS can achieve at least 87% of coverage even when the number of vehicles is as low as 20.