Cellular System Performance

CELLULAR SYSTEM PERFORMANCE INFORMATION
Most complaints relating to the performance of the cellular telephone are not due to a malfunction of the Lexus Telephone System or the Cellular Network itself. It is more likely that the cause lies in the characteristics inherent to wireness communications.

Radio signals both transmitted and received by the cellular telephone work best when there is an unobstructed path between the vehicle's antenna and the network's "base site" antennas.

Because of the reflecting characteristics of the cellular phone radio signal, directed and reflected signals may reach the antenna at the same time. ("multipath"). They cancel each other out creating small "islands" where audio "nulls" occur. As the car moves through these spots, the caller will hear a momentary flutter. This same characteristic causes "ghost" images in television when an airplane flies over.

Multipath can also cause a "cross-talk" phenomenon, where the driver may temporarily hear another cellular conversation.

Other common symptoms which may occur in a cellular conversation are:

Symptom - Cause

Static - Lack of coverage or "Multi-path" condition.

Crosstalk (co-channel or adjacent channel interference or receiver intermodulation) - The cellular telephone has captured a "voice channel" from another base site due to weak coverage or multi-path condition. This is a landline or system coverage problem.

Dropped Calls - Weak coverage area, multi-path condition, or "system" drop.

Clicks/occasional chopped word - System handoff to another base site.

Increased/decreased volume at either landline or vehicle Echo or feedback The current "voice channel" that the system has assigned to the cellular telephone has a higher or lower gain, or more or less "sidetone" compared to a previous channel/