Research On HAPS-based Integrate Networking And Its Application In Forest Region Communication

The high altitude platform communication system (HAPCS) is a newcommunication architecture with the superiority of wide coverage, high capacity andflexible network framework. HAPCS could provide3G/4G and broadband accessservices for terrestrial users, which is especially attractive for the users in forest region.The traditional forest region communication system has the problem of limited coverage,low capacity, monotonous service and etc. Because the highly complicated forest regionhas serious multi-path fading and shadowing effect in the uplink, which degrade theperformance of forest communication significantly. In order to alleviate the influence ofmulti-path and shadowing effect, we incorporate the cooperation relaying technologywith HAPCS in this thesis, and improve the performance of forest regioncommunication system by integrating the relay on ground and HAPCS. The maincontributions of this paper include:Firstly, the current situation of forest region communications is analyzed, and theexisting problems are pointed out. The requirements of forest region communicationsare analyzed and estimated based on the features of forest fire fighting of Forest Armyof People’s Armed Police. The results indicate that the current forest region networkscannot satisfy the communication requirements of forest fire fighting underinformation-based conditions, thus new technologies such as high altitude platform(HAP) and cooperative relay should be employed to improve the performance of theforest region communication networks.Secondly, by analyzing the coverage ability and the channel feature of HAP, theintegrated network composed of ground relays and HAP is proposed to relieve theshadowing effect, which is caused by mountains or trees in the forest communicationenvironment. A framework of the integrated network is designed, which include thesystem composition, spectrum assignment and cell allocation.Thirdly, considering the application scenario of forest fire fighting of Forest Armyof People’s Armed Police, two cooperative schemes in the uplink are modeled for theintegrated network users. Based on the different channel conditions in differentcoverage areas of HAP, bit-error-rate (BER) performances of three cooperativetransmission schemes, namely AF, DF (with CRC check) and DF (without CRC check),in different elevation angle areas are analyzed and compared. The results indicate thatcooperative relaying technology could significantly improve the performances in themiddle and low elevation angle areas and the DF (with CRC check) could obtain thelargest diversity gain.Fourthly, the user capacity is estimated in the integrated network composed ofHAP and ground base stations. Aiming at relieving the mutual interference of multiple users and thus improving the user capacity, base stations are deployed in the edge ofHAP cells. The system model is proposed for this scheme, and the mutual interferenceand capacity calculations are carried out under the system model. The results show thatdeploying base stations in the edge of HAP cells decreases the mutual interferencesignificantly. The proposed scheme increases the user capacity by78.4%compared withpure HAPCS.At last, based on the analysis on the requirements of forest region communications,an efficiency evaluation system for the integrated network of HAP is designed. By usingthe qualitative and quantitative indexes that obtained by the researches on the keytechnologies of cooperative relaying transmission and capacity analysis, the efficiencyof integrated networks proposed in this paper is evaluated by using the analytichierarchy process (AHP) efficiency evaluation method. The results show that ourproposed scheme outperforms the current forest ultra-short wave networks in networkefficiency, and the proposed scheme satisfies the communication requirement in forestfire fighting.