In multimedia transmission there are some services that require higher transmission rate. These services can be transmitted via communication channel in two different ways. The first way is single code with transmission. It is established with code spread degree reduction. The second way is multi code transmission. It is established in the mode that total bit sequence of increased speed is split up into parallel sequences of basic speed. Every sequence of basic speed is transmitted with individual code without code spread degree reduction. The most important criteria when choosing operating mode is maximal possible number of active users in the system cell without quality degradation of the most demanding service. The number of active mobile communication system users DSCDMA is limited by interference conditions within a system. Thus, interference conditions have been investigated detailed. Interference condition consideration of multi cell mobile communication system for different operating modes within a cell for uplink and down link transmission direction has been carried out by mathematical statistical approach. With the assumption of the uniform active mobile user density on the cell surface a calculation of interference conditions has been performed. Achieved results obtained by using this approach for the uplink transmission have been compared to results obtained by some other authors. The other author results have been obtained using different mathematical approach with the same starting assumptions. Comparison has showed complete close up in the physical legitimacy and great coincidence in numerically showed values. Statistical method has enabled determination of interference factors in the uplink and downlink transmission direction. For the purpose of calculation of interference conditions, interference calculation correction factor for the uplink and downlink transmission direction has been defined. Definition of interference correction factor is different comparing to some other authors definitions. Other authors define interference correction factor as the ratio of received interference power against generated interference power in the observed cell. In this dissertation the interference correction factor has been defined as the ratio of received surrounding interference power against received power from the observed cell. Stated difference in definition has been done because of several reasons. The first reason is that this definition of strength has enabled its better application in equations for calculation of signal noise ratio on the receiver entrance. The second reason is that such definition of interference correction factor has enabled direct calculation of reduction factor of number of possible active user on the cell system surface. The reduction factor presents reduction of possible number of active users on the cell system surface. This reduction can be described as relative drop of number of users which happens when isolated system is fitted into multi cell structure. The reduction factor in the physical sense represents the power ratio which would be on the receiver entrance when system is isolated against the power which should be on the receiver entrance when the observed cell is fitted into multi cell system. Calculation of interference conditions for the uplink and downlink transmission direction by using statistical method has enabled complete understanding of interference conditions on multi cell mobile communication system. Calculation of interference values has been performed for different cell working modes what has enabled calculation of maximal possible number of active mobile users on the cell surface. Mathematical equations, those describe possible active mobile user number or codes on the cell surface if a single mode or multi mode without reduction or partly dispersion code reduction, have been set up. Those mathematical equations of possible active user number or codes are set up for cells with no-directivity, sector or intelligent antennas. All curves that describe number of remaining users for single code or multi code working mode have intersection into one point. This point is called intersection point. It has been determined on which signal and system parameters depends intersection point. Based on performed analysis a general low of multi cell DS-CDMA system has been defined. This low shows if the signal of certain characteristic can be transmitted using mobile communication channel. The end of dissertation explains factors that affects on choosing of working method and defines relations between them.