Wireless networks are based on transmission and reception of Radio Frequency (RF) electro-magnetic waves between at least two devices. During operation, the RF connection will experience a wide range of attenuations due to e.g., atmospheric effects, intervening obstacles, etc. Generally, it is assumed that the radio link between two devices is substantially symmetric; i.e., transmit and receive RF links for a given device are substantially similar in performance and attenuation. In symmetric link operation, each device assumes that their perceived performance is representative of a peer device's perceived performance at the other end of an RF link.
However, empirical evidence suggests that certain device usage scenarios can create asymmetric attenuation in each direction of an RF link, e.g. in transmit and receive RF links for a given device. For example, a user operating a wireless communication device (such as e.g., the iPad™ developed and manufactured by the Assignee hereof) in communication with a nearby Long Term Evolution (LTE) cellular network can experience a wide range of radio link performance based on e.g., the positioning of the wireless communication device with respect to the user's body. Specifically, the wireless communication device's RF transceiver may be configured to limit transmit power when the transmitter is next to the user's body (or adjacent to another object). The degree of transmit power reduction or attenuation at the wireless communication device can be based on, in one case, regulatory concerns, which can dictate Specific Absorption Rate (SAR) requirements permitted for emitted RF energy by the wireless communication device.
In the foregoing scenario, only the transmit link may be affected by the regulatory provisions, which can limit operating conditions and therefore influence performance; the receive link can remain fully operational. In some situations, the wireless communication device may not be able to successfully interact with a wireless network because its transmit power may be limited, and transmissions may be necessary to establish and/or to maintain an RF link with the wireless network, (i.e., the wireless communication device can be unable to set up the link by only receiving commands or data from a wireless network.) To make matters worse, since reception quality at the wireless communication device can be acceptable in this scenario, the wireless communication device may be unable to attempt to invoke remedial or corrective action; e.g., execute a handover to another LTE evolved NodeB (eNB), perform a cell selection/reselection, etc. Existing wireless communication devices may therefore be caught in a marginal and/or unusable operational state, thereby degrading performance and user experience.
Accordingly, improved methods and apparatus are needed for handling radio link imbalances such as for example those described in the foregoing scenario.