家用基地台系統下本地IP封包存取機制之改良

Abstract

長程演進技術(LTE)為備受矚目的新一代行動無線寬頻技術，目前已被第三代行動通訊組織(3GPP)列為全新的無線標準技術。LTE提供一些優於其他cellular網路的競爭優勢，包括提升end-user吞吐量和減少封包傳送的延遲時間等。根據目前LTE目前架構當家用基地台(HeNB)下的手持裝置(UE)想要送到近端網路中的某個UE時，其資料必須由UE傳遞至核心網路後，再由網際網路傳送至UE所屬的家用網路，最後再送至該UE，而這種傳送方法會有些缺點如資料的傳送速度會被後端的家用網路所限制、較高的延遲(Latency)與抖動(Jitter)、資料外洩的可能。 本論文根據本地IP封包存取(Local IP Access)機制中提出一改良機制。此機制可以達到加快使用者的傳輸封包使之直接連結家裡的區域網路，不經過營運商的核心網路，首先會在HeNB裡加置新模組HMME 來完成NAS Messages Handler 與Local IP Access Service，而方法是應用手機與基地台中的Data Radio Bearer 作為偵測的Detection Radio-Bearer來偵測情景為當封包傳輸為內部傳輸類型即轉為Transmission Radio-Bearer ，此通道將會用於專門傳輸符合該通道條件之內部傳輸封包，並在通訊協定層中只讓傳輸封包到達PDCP層時即利用資訊CRNTI(使用者UE_ID)與DRB_ID(DTCH_ID)利用查表方始將其轉發至本地使用裝置已達成本地封包快速傳輸，因為完全無使用外部網路資源因此可以降低網路營運者的資源成本。

Long Term Evolution (LTE) is expected to ensure 3GPP's competitive edge over other cellular technologies. The advantages of LTE include improving end-user throughputs, and reducing latency. According to the LTE system when the user equipment (UE) of home base station (HeNB) which wanted to send packets to another UE, these packets must be go through the core network of operator, then go back to HeNB, and finally send to the UE. This delivery method has some drawbacks such as data throughput will be restricted by core network, higher latency (latency), jitter (Jitter) and the possibility of private information leakage. This thesis proposes an improved Local IP Access mechanism. This improvement can transport local packets of the user without the operator's core network. The new module HMME will be there at first, which deal with NAS Messages Handler and Local IP Access Service, and the detail method is using Data Radio Bearer which between UE and HeNB as the Detection Radio-Bearer to detect the local packets. If there have local packets, the Detection Radio-Bearer will change into Transmission Radio-Bearer, this Bearer will be used by only transport local packets. When local packet arrives at the PDCP layer, HMME will use the information of CRNTI (user UE_ID) and DRB_ID (DTCH_ID) to check the table, then forwarding it to the target local device directly.