4G LTE行動通訊特許執照確定之後，各電信營運商無不卯足全勁全力建設網路，然而在此競爭激烈的市場中，電信營運商唯有讓使用者有良好的使用體驗，才能爭取到消費者的青睞，而良好的使用體驗來自於綿密且優良的訊號涵蓋，而行動網路中最基礎的一環就是網路的建設。但無論是取得新執照的既有3G業者或初入此市場的新競爭者，在建設完整的無線網路時將會面臨到網路建設各階段中不同的問題。 在建設的第一階段，電信營運商會佈建大細胞基站(Macro Cell Site)，而為了讓涵蓋區域的擴大與增加新的涵蓋區域，電信營運商在第二階段會增加建設更多的大細胞基站，以期望形成連續的涵蓋範圍。在於第三階段電信營運商會基於建設成本(CAPEX)與無法建設等等的因素，再無法用新建大細胞基站的方式來補足訊號涵蓋，且營運商也會一併考量大細胞基站建置過近時，過多重複的訊號涵蓋將造成無線網路嚴重的互相干擾，因此以現有的網路建設模式而言，無線網路中將仍存在不少的訊號涵蓋缺口(coverage hole)。 基於上述理由，設備成本相對低廉、建設容易、維護容易的小細胞基地站(Small Cell Site)孕育而生。於訊號涵蓋缺口的區域佈建小細胞基站可以補強無線網路終端裝置接收到的訊號強度(RSSI)，且小細胞基站的簡易設置可以有效降低營運商一般的維運成本(OPEX)。然而如何將小細胞基站放置於相對的最佳位置上，將是本論文所要探討的議題。 ;Mobile communication market will be an intense competition region after releasing the 4G LTE license. There more and more thesis and papers are involving the innovation technology LTE. The new or existing operators are preparing for its coming. Operators have to keep their network in dense coverage and good performance for improving customer’s experience. In Conventional 3G network are built by Macro cell sites outdoor. There were many coverage holes were causing by shadowing by the building or fast fading and terrains. It will increase Capital expenditures (CAPEX) when built two Macro cell sites too close. Furthermore, it will increase interference between adjacent sites. Base on the reasons we found, small cell sites born to solve the issue. Small cell sites were much cheaper than Macro cell sites. It is easy for deployment and easy for maintain. It can bring up to full strength of network RSSI issue in designated area. It can improve user DL/UL performance. User will have a wonderful using experience. Operator can also reduce the Operating Expense (OPEX). The placement is the key of deployment small cell sites. We can find the background and research motivation in section 1. Planning and building scheme the Marco cell and small cell sites will be present in section 2. Deployment strategies and PSO algorithm was described in section 3. Experiment and simulation result will be in section 4. The section 5 is the conclusion and the future work.