Inter-Cell Interference Mitigation

Abstract

To address the problem of inter-cell interference in a heterogeneous network, several methods and systems are disclosed for determining interference caused by an aggressor mobile node, and transmitting at appropriate times and with transmit power that does not cause interference. Methods disclosed include using X2 communications, such as HII and RNTP messages, switching to an alternative radio access technology, sniffing at the eNodeB to obtain information, coordinating with a cloud coordination server, and using CFI information to avoid interfering with communications on the PDCCH.

1 . A method for reducing uplink interference at a first base station, comprising:
 assessing frequency resources shared between the first and a second base station to determine frequency resources that cause reduced interference at the first base station in comparison to other shared uplink frequency resources.   determining whether mobile devices connected to the first base station may be switched to a Wi-Fi connection; and   switching services provided to the mobile devices to a Wi-Fi connection between the mobile devices and the first base station.   
     
     
         2 . The method of  claim 1 , further comprising determining whether each mobile device of the mobile devices is capable of using Wi-Fi. 
     
     
         3 . The method of  claim 1 , further comprising determining whether each mobile device of the mobile devices is within a Wi-Fi-capable range. 
     
     
         4 . The method of  claim 1 , further comprising determining whether radio frequency resources are available for using Wi-Fi. 
     
     
         5 . The method of  claim 1 , further comprising determining at a controller whether to switch to Wi-Fi based on one or more of: a number of mobile devices already attached to the first base station on Wi-Fi; bandwidth required for switching a specific mobile device to Wi-Fi; backhaul network capacity; system load; and a relative load of one or more base stations. 
     
     
         6 . A method for reducing interference at a first base station, comprising:
 at the first base station, sniffing shared frequency resources on the uplink of a second base station; and   based on the sniffed frequency resources, identifying low interference resources for uplink scheduling use by the first base station.   
     
     
         7 . The method of  claim 6 , wherein sniffing frequency resources further comprises:
 receiving signals over a plurality of radio frequency bands; and   performing power spectral density analysis over the plurality of radio frequency bands.   
     
     
         8 . The method of  claim 6 , further comprising sniffing frequency resources at intervals over a period of time. 
     
     
         9 . The method of  claim 6 , wherein sniffing frequency resources is performed at a digital signal processor at the first base station. 
     
     
         10 . The method of  claim 6 , further comprising transmitting an overload indicator (OI) message via an X2 protocol from the first base station to the second base station to cause the second base station to reduce transmission power. 
     
     
         11 . The method of  claim 6 , wherein the first base station in coordination with a controller determines whether mobile devices connected to the first base station may be switched to a Wi-Fi connection. 
     
     
         12 . A method for reducing uplink interference at a second base station, comprising:
 receiving, at a first base station, measurement information from one or more of a mobile device attached to the first base station; and   based on the received measurement information and on a coverage radius of the first base station, sending a power configuration message to the mobile device to limit the transmit power of signals from the mobile device to the first base station.   
     
     
         13 . The method of  claim 12 , the measurement information further comprising measurement reports received from a user equipment and system information block messages from the second base station. 
     
     
         14 . The method of  claim 12 , further comprising sending a power configuration message to the mobile device to limit a ratio of transmission power and noise to below a specific threshold for transmissions from the mobile device. 
     
     
         15 . The method of  claim 12 , wherein the first base station determines, in coordination with a controller, whether mobile devices connected to the mobile base station may be switched to a Wi-Fi connection.