一種運用中繼節點的LTE-A下行網路節能設計

Abstract

在行動網路朝著速度更快，涵蓋範圍更廣更全面的同時，行動電信業者也面臨需要消耗大量電費支出以維持基地台運作的嚴重問題。無線網路的省電因此成了電信業者在發展LTE-A等未來行動網路時同步進行之重要研究目標。 一個無線網路系統為了要滿足使用者的需求，往往需要增加基地台的鋪設或是提升基地台發射的功率，但此方法對於室內使用者卻事倍功半。為了有效提高室內使用者的網路速率，並且兼顧室外使用者的服務品質，我們認為引進可將信號延伸至室內的中繼節點是一個有效且合理的解決方式。本論文提出一個中繼節點資源共享演算法(RRSS)，針對各個中繼節點可獨立發射信號且不易互相干擾的特性，來有效提高頻譜使用效率，以期提升使用者滿意度，並且在合理的發射功率下提升主基地台有效服務涵蓋半徑。 經過模擬的驗證，本論文證實加入RRSS的機制能夠提升使用者對其服務的滿意度。並證明在維持使用者滿意度以及使用者密度不變的前提下，使用了RRSS這個機制能夠讓主基地台維持合理的發射功率而提高有效的服務涵蓋半徑。更能針對使用者密度較低的地區，減少主基地台的布建，進而減少能源消耗，同時因此降低營運商在無線網路所需要投注的電費成本。本論文之研究成果應可佐證這樣的架構在未來行動電信網路節能上，具有高度可行性。

As global mobile networks evolve toward faster and ubiquitous wireless network systems, the mobile network operators also encounter the problem that the operation of base stations would introduce high cost then before due to the expenditure of the electricity. Thus, making the network system more energy saving has become an important research target for those operators, in parallel to the LTE-A research. In order to meet the users’ need, the operators must deploy more base stations or increase the transmission power of the stations. However, this may not be effective for most indoor users. We belieave that the deployment of the relay stations would be an effective and reasonable solution to raise the indoor users’ data rate while not deteriorate the outdoor users’ service. We proposed a novel algorithm, called Relay Resource Sharing Scheme(RRSS), with the feature that many relay stations could transmit signals in the same frequency band to indoor users individually with low interference. This scheme has shown that it could increase the spectrum efficiency, enhance the user satisfaction rate, and increase the coverage radius of the base stations within a reasonable transmission power. The simulation results prove that the RRSS can effectively enhance the user satisfaction rate. Under a fixed targeted user satisfaction rate and user density of an area, the RRSS mechanism could keep the base station’s transmission power within a reasonable range and still could increase its coverage radius. For the low user density areas, the operators could decrease the number of deployments of base stations, and then decrease the energy consumption. In the end, the expenditure on electricity bills can be reduced. In other words, the results of this thesis should have proven the evidence that the energy-saving capability of the proposed architecture is feasible for future mobile networks.