Gprs - wirelessfuture.it · the main GSM-GPRS radio access functionalities GANIMEDE runs in time-driven dynamic mode, and the simulation step is the timeŒslot duration GANIMEDE supports

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GANIMEDEGANIMEDEGSMGSM--GPRS NetworkGPRS NetworkDynamic SimulatorDynamic Simulator

wwithithGraphic User InterfaceGraphic User Interface

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• GANIMEDE is a system dynamic simulator that implements the main GSM-GPRS radio access functionalities

• GANIMEDE runs in time-driven dynamic mode, and the simulation step is the time–slot duration

• GANIMEDE supports two different scenario types:� monocellular, where users always stand in their initial

goegraphic position� multicellular, with many sites and with complete user

mobility (it is possible to implement different mobility models)

ABOUTABOUT GANIMEDE…GANIMEDE…


GRAPHIC USER INTERFACEGRAPHIC USER INTERFACE

• GANIMEDE is provided with a graphic user inreface, that allows every user to utilize it in a very simple way

• This interface is organized in windows; each of these shows either a group of entries to be filled (in case of parameters setting) or a group of graphs related to a set of variables (in case of output results analysis)

• The user takes decisions simply writing something in an entry and/or clicking a button


GANIMEDE ARCHITECTUREGANIMEDE ARCHITECTURE• GANIMEDE has been structured on the ISO-OSI network

model

• GANIMEDE implements the following layers:� physical layer� MAC layer� RLC layer� RRM layer

• TDMA radio frame is the main time structure involved in the simulation, even if many procedures are made every time slot


GANIMEDE STRUCTUREGANIMEDE STRUCTURE

GRAPHICGRAPHICUSERUSER

INTERFACEINTERFACE

INPUT PARAMETERS

TRAFFIC TRAFFIC GENERATORGENERATOR

INPUT FILES INPUT FILES GENERATORGENERATOR

GANIMEDEGANIMEDEDATA TRAFFIC

SPEECH TRAFFIC

FREQUENCY PLANNING

SIMULATION PLANNING

SPEECH GRAPHS DATA GRAPHS

SPEECH OUTPUTS

DATA OUTPUTSPOSTPROCESSING POSTPROCESSING TOOLTOOL

CELL OUTPUTS

CELL GRAPHS


PHYSICAL LAYERPHYSICAL LAYER• The physical layer is simulated on a time-slot basis for

every carrier of each site in the system, taking in account:� the state of every channel (i.e. time-slot)� the received signals power level� the interference coming from other cells

� In a multicellular scenario the interference comes from other cells, and can be directly measured

� In a monocellular scenario, since there is only one cell, the direct measure is not possible; therefore the external interference is obtained through a statistical model


MAC LAYERMAC LAYER• MAC layer is simulated on a radio frame basis for every

user

• MAC layer is responsible for the assignment of resources to the users in the next radio frame

• The decisions are taken considering the informationscoming from RRM layer and users requirements

• It is possible to implement more than one radio resource handling strategy; for all these reasons, thislayer is the core of GANIMEDE


RLC LAYERRLC LAYER

• RLC layer is simulated on a radio frame basis for every radio link

• RLC layer is responsible for the status update of each radio link

• It generates channel assignment and release requests for MAC layer

• It generates the appropriate commands for packet retransmission from the instantaneous CIR value of a radio link and the corresponding BLER value, mapped on curves for each standardized TU channel


RRM LAYERRRM LAYER

• RRM layer is simulated on a radio frame basis for every new service request

• RRM layer is responsible for the admission control of GSM users (nothing is done for GPRS users)

• It monitors the state of the whole radio resources, and sends the appropriate informations to MAC layer

• It manages new connection requests and, in case of multicellular scenario, handover events


MAIN FUNCTIONALITIES (I)MAIN FUNCTIONALITIES (I)

• GANIMEDE grants the maximum flexibility about GPRS radio resource handling strategies: it is possible toutilize different techniques of PRM

• GANIMEDE supports two different modes of operation for GSM terminals:� full rate, that allows only one user to reside on a

time slot� half rate, that allows up to two users to reside on a

time slot


MAIN FUNCTIONALITIES (II)MAIN FUNCTIONALITIES (II)

• GANIMEDE provides a statistical method to generate external interference in case of monocellularenvironment� since interference is the sum of a large number of

log-normal random variables, it is a log-normal random variable too

� each value is generated from its average and its standard deviation, that are already set in the simulator


MAIN FUNCTIONALITIES (III)MAIN FUNCTIONALITIES (III)

• GANIMEDE implements the standard cell selection and reselection algorithm in case of multicellularenvironment � since the delay caused by this procedure is unknown,

it is possible to set a fixed value as an input parameter

� so it is possible to study the impact of this feature on the services in terms of additional delay

• GANIMEDE can implement different mobility models and process many scenarios


INPUTS & OUTPUTS (I)INPUTS & OUTPUTS (I)• GANIMEDE needs the following inputs:

� cell parameters: number of carriers, number of SDCCH/4 and SDCCH/8, radio resource handling algorithm peculiar parameters (i.e. GPRS dedicated resources, GPRS users PDCH multiplexing thersholds,…)

� system parameters: simulation duration, radio resource handling algorithm, half-rate threshold, area informations

� traffic parameters: speech and data services are always kept separated, so it is necessary to characterize both types of traffic

�speech: call duration, erlang per cell, terminal class

�data: session duration, erlang per cell, average packet interarrival time


INPUTS & OUTPUTS (II)INPUTS & OUTPUTS (II)

• Speech traffic model considers a Poisson arrival process; the duration of each service is exponentially distributed around the average value

• Data traffic model considers a Poisson arrival process; actually only web browsingweb browsing is implemented: the duration of every session is exponentially distributed around the average value; each session is split in packets of fixed size; their arrival times are calculated through an exponential distribution of the average interarrival time � it is possible to introduce new services and new

models for data traffic (e.g. MMS, audio and video streaming,…), in order to study a traffic mix scenario


• GANIMEDE provides the following outputs, according to the separation of GSM and GPRS services:� speech: block rate, full-rate and half-rate

connections percentage� data: average session bit rate, average packet delay,

throughput, total amount of data carried by the network

� site: GSM and GPRS amount of allocated resources, PDCH utilization degree, handovers and cell-reselections events

INPUTS & OUTPUTS (III)INPUTS & OUTPUTS (III)


INPUTS & OUTPUTS (IV)INPUTS & OUTPUTS (IV)

• After the postprocessing phase, the outputs are displayed in two types of graph� time graphs, that show the progression of the

variables during the simulation time� statistical graphs, that show both the cumulative

function and the density of these variables


ITS CAPABILITIESITS CAPABILITIES• GANIMEDE allows its users to study and analyze various

GSM-GPRS system configurations� it is possible to compare different settings of cell

parameters either using monocellular environment in many simulations or using multicellular environmetin one simulation

� it is possible to evaluate the effectiveness of frequency planning in each cell

� it is possible to compare different radio resourcemanagement strategies in order to fulfil the largest number of service requests (e.g. half-rate vs GPRS resources permanent allocation)

• So GANIMEDE can be used as a network planning and optimization tool

Documents

Gprs - wirelessfuture.it · the main GSM-GPRS radio access functionalities GANIMEDE runs in time-driven dynamic mode, and the simulation step is the timeŒslot duration GANIMEDE supports