Effect of co-existence interferences on QoS of HSPA/WCDMA mobile networks

The rising density of wireless networks and the related rising number of user equipment increase the vulnerability of interference generation. These interfering signals could be generated as the result of the co-existence of wireless standards like DVB-T, LTE, WCDMA, WiMAX, GSM, Wi-Fi and other services transmitted in adjacent bands of the radio spectrum. The received signals are mixed with the higher order modulation products on the nonlinearity of amplifier. Next, the generated interfering signals are radiated back to the radio environment. With sufficient power the mixed signals could overlay an inter or intra system channel and thus interfere useful signals of surrounding transmissions. This paper introduces the influence of interfering signals on transmission parameters in the 3G HSPA mobile network. Our measurement is carried out in a real 3G UMTS network using HSPA user equipment. The bandwidth of interfering signals is chosen in compliance with the possible scenarios generating higher order modulation products and also the possible scenario of cognitive radio applications. The workplace, theoretical background and the measurement principles of the performed method are introduced and briefly described. The impact of bandwidth and power of the interfering signals on the quality of services in the mobile network is represented as the change of CQI, data rates, the number of allocated channelization codes in downlink shared channel and also the increase of signaling and data traffic required for repeated transmission of the corrupted signal. The obtained results are evaluated and described.