Competitor induced mobile intermodulation interference in cellular mobile phones

Theoretically, interference between cellular carriers is minimized by allocating to each operator a partitioned, dedicated spectrum (A-band and B-band, respectively). Customers typically subscribe to a single carrier (server) and are not supported by the alternate carrier (competitor). In practice, however, intermittent interference problems occur when cellular mobile phones come within close vicinity of high ERP competitor cell sites. Two frequently reported competitor-induced interference symptoms are “No Service” indication, and the inability to establish or receive a call. This paper asserts that this interference is due to strong third-order intermodulation products generated within the cellular mobile phone receiver, which produce co-channel interfering signals in the server´s spectrum. Each competitor´s cell site has its own particular interference area, defined by specific server versus competitor signal strength thresholds. This paper derives a theoretical mobile intermodulation (MIM) interference prediction model based on EIA IS-19 and IS-55 specifications. Additionally, this paper confirms the accuracy of the theoretical prediction model with a series of measurements on a test cellular system