Research And Development Of Simulator Based On Radio Network Of PHS Packet Data Network

PHS (Personal Handset Phone System) is a kind of mobile communication system based on the technology of digit communication。PHS and GSM, narrowband CDMA which are widely employed in the world belong to the Second Generation communication system.The architecture for packet data network in PHS is very complicated, the information flow is processed trivially from PS to CS and from CS to core network. PDS(Packet Data Server) is the key network element in packet data network in PHS, it owns many functions, so it is a tough task to develop PDS. In order to guarantee the development procedure for PDS, it is very important to design a new simulation scheme for PDS. Depending on the simulation scheme, PDS could be involved in the call procedure in PHS for simulation test. Then the communication process and session scenario will be displayed in advance.As a result, the error and shortcoming will be found fastly, and the scheme could save cost, improve the developing efficiency, safeguard the quality of the product, perfect the function and performance for PDS.The project team , in ShenZhen Branch for UTstarcom , which the author belong to, is responsible for developing PDS in core network of packet data network for PHS. In those days, the author and several engineers others are responsible for the simulation for the session scenarioes and the message flow. We research PHS packet data network and processing for the message flow, and design a new, effective simulation scheme for PDS.On basis of researching GTP protocol, PPMP protocol, call procedures in PHS packet data network, and others basic theory, design in general for the new simulation scheme, includes its architecture, the role for every component and the communication method for each other. And he simulation scheme is taken into a concrete realization of a user interface, state controllerand protocol controller for a three-tier structure. Among them, the user interface to parse the user's script and the control orders of running script for user; State Controller to control the internal message exchanging between the user interface and the protocol controller and the states of others componets exclude the state controller; and the protocol controller to deal with the corresponding protocol, the corresponding protocol packet analysis or packaging. For the ommunication between this three-tier structure the classical C/S architecture is used, and the technology for UNIX Domain Socket and stream socket is to be achieved.Author's specific development work is the design and implementation of PPMP component for the protocol controller, this job includes GTP protocol and PPMP protocol,communication with the PPP component and APP component and USER component and the interaction with each other, communication with PDS, and the simulation of session procedures between wireless access network and PDS in PHS packet data network. Specific job includes : establishing the data structure for GTP context and PPMP context,and so on; design the functions in user interface components for parsing the parameters and for the commands supplied to user; construct the standard protocol package for parse it; process timer events; processing log records document; design some special instructions for test users ,which could reach better control Call; when need to find the GTP for PPMP context, use open address aouble-hash method to achieve the rapid-positioning of context, to solve the problem of the performance bottleneck of the system. The open address double-hash method is addressed simply below。The idea for this algorithm: Hash the keyword with the prime number P1 to get a initial index. Once the table space for corresponding index is occupied by another keyword, then hash the keyword again with the prime number P2, so could get the new index.When conflict occurs, the double-hash function sequence for exploringcan be summed up as (h1 (key) + h2 (key)) mo d N, (h1 (key) +2 h2 (key)) mod N, (h1 (key) +3 h2 (key)) mod N, ... ..) in which, h1 (key) represents first Hash for the keyword, h1 (key) = (P1 x K) modulo N; h2 (key) represents second Hash for the keyword, h2 (key) = P2 x K) modulo N; P1, P2 as the prime, K for the keyword folded , N as the length of the table.In the process of finishing this paper, because of limited time, complexity of project, faculty of author, the author design and implement the PPMP component for processing GTP and PPMP protocol to simulate the session scenarios between PDS and radio and PHS packet data network. For application part, the unit test for PDS has finished, and the integration test for PDS is under processing. The development for Simulator is a tough task, the engineers must continually update and maintain it according to different requirement for test. But, as the Simulator is perfected little by little, it will improves the development for PDS.Now, Simulator has meet the need for unit test for PDS, and it has passed most part of the system test initiated by professional testers, while some cases are under processing.