| 摘要: | 進階長程演進網路(Long Term Evolution-Advanced, LTE-A)是由3GPP所制定的高速無線網路的標準，主要目的要能夠達到International Mobile Telecommunications Advanced (IMT-Advanced)的內容規範，因此3GPP在LTE-A中引進了載波聚合(Carrier Aggregation；CA)的技術。而3GPP在LTE Release-8也建置毫微微型基地台(Femtocell) ，幫助減緩大型基地台(Macrocell)之負擔。但是由於Femtocell不像大型基地台是經過規劃後架設，因此容易造成不規則的佈建狀況，導致基地台與使用者設備間(User Equipment)的訊號干擾，使得整體的載波利用率及傳輸速度降低。
因此3GPP提出了載波自主重新分配選擇(Autonomous Component Carrier Selection； ACCS)的方法，每個基地台會優先選擇未被鄰近基地台使用的載波，以避免基地台不規則佈建所產生的載波干擾。但由於ACCS的配置方法並不完善，仍舊會導致的載波使用率較差、系統傳輸量不佳、亦或是會造成能夠與基地台取得連線的使用者設備數量低落等問題，故本論文將以提升使用者連線數為主要目標，在ACCS的基本載波分配方法架構下提出一個新的載波重新分配方法，此方法在基地台因干擾而無法配置載波資源時，基地台重新考量當前所有使用者設備受干擾情況，對UE進行排程再依照載波情況選擇適合的載波配置。模擬結果顯示，本論文研究提出的使用者排程重新分配機制能提升主載波的資源分配數量以達成更多的使用者連線數，同時提升次載波的資源分配數量來滿足使用者設備的頻寬需求。
The 3GPP defines Long Term Evolution - Advanced (LTE-A) as a wireless network standard for high packet transmission rate and low packet latency provisions.To comply with the regulations of the international mobile telecommunications advanced (IMT-Advanced), 3GPP utilizes the technology of carrier aggregation (CA) in LTE-A. Besides, 3GPP in the LTE Release-8 also advocates the communications industry to establish femtocells to reduce the pressure of macrocells. However, unlike macrocells, which is established after elaborate planning, HeNB is much more easy to lead to irregular establishment. Thus, this condition will bring about signal interference between base stations and user equipment (UE), which makes the whole carrier utility and throughput speed lower.
Therefore, 3GPP proposes the approach of autonomous component carrier selection (ACCS), ACCS lets every base station select the carrier which is not used by near base stations to avoid the carrier interference caused by the irregular establishment of HeNB. However, this selection is imperfect and it results in poor throughput and carrier utility and low the connection of UE.
In this thesis, we propose a new ACCS based on user scheduling under the basic CA selection framework of ACCS.This method when the base station can not be allocated with carrier resources because of the interference, base station would check the current user equipment’s interference situation, UEs will be scheduled by interference situation, then the base station select the appropriate carrier distribution for the schedule. Finally, the simulation results show that method proposed by this study can raise resource distribution of main carrier to attain more users’ connection and simultaneously elevate the resource distribution of sub-carrier to meet the demands of UE bandwidth. |
