Mobile communications have become widespread in metropolitan areas around the world, and also outside metropolitan areas in many countries. In industrialized countries there is access to mobile communications along all major roads and motorways. The rapid growth of mobile communications and the competition among service providers has meant that communication networks often operate at capacity. There are a number of mobile communication systems that have achieved success in the marketplace, including analog cellular, digital cellular, time divisioned and code divisioned systems, as are well known in the art. It is quite typical in metropolitan regions that several competing network operators will be providing access to their respective subscribers. However, in response to communication services sometimes not being available because the subscriber's service provider is at capacity in the region where the subscriber is presently located, some manufacturers have begun designing and manufacturing multi-mode mobile communication devices. These multi-mode mobile communication devices are capable of interfacing with more than one mobile communication network, often using more than one air interface. An air interface describes the frequency, modulation, encoding, encryption, control protocols, traffic protocols, and so on. Therefore a multi-mode communication device will allow a user to switch to a different mobile communication service provider's network if the user's preferred system is unavailable due to capacity or other reasons.
However, while implementing multiple receiver paths in the mobile communication device has a only a relatively small effect on the cost to manufacture a mobile communication device, adding an additional transmit path capable of transmitting at the necessary power needed for mobile communication is much more expensive. Therefore it is desirable to have only a single transmitter in a multi-mode mobile communication device. This leads to problems when the mobile communication device is engaged with more than one communication system and the mobile communication device would ordinarily be required to transmit simultaneously to both systems at some time. Therefore a transmit event arbitration scheme is necessary to avoid having to implement multiple transmitters in a multi-mode mobile communication device. However, while it would be possible to perform such arbitration under software control, experience has shown that to do so, with complex protocols, can itself require complex and extensive coding. It would be more preferable to perform arbitration by relying on hardware more than software.