Another case of interference is the interference received by the mobile 2, we assume that this device is managed by the macro-cell and does not have permission to access the femto-cell 1, however, it is within the coverage area of the femto-cell, this will produce interference with the mobile device, since the frequency channels for communicating with the macro-cell and femto-cell are located in the same frequency band, this type of interference is produced from femto-cell to macro-cell, it can also occur in the opposite direction from macro-cell to femto-cell.
When a mobile is managed by a macrocell and it is far from eNodeB and close to a femto-cell, it will transmit at a higher power to cover losses associated with the link, however, in doing so, generates more interference to the femto-cell. Moreover, the femto-cell will request to the managed mobiles, an increment in the transmission power to cover the interference, this in turn, will generate a higher level of interference to the mobile which is managed by the macro-cell. The network access methods will have to manage the problem of power management in an efficient way to allow coexistence and ensure quality of service.
In this context, a problem arises concerning the femto-cell coverage management, since it should minimize interference from them, and simultaneously, meet the requirements of service quality. Therefore, the service provider must have a precise control of the femto-cell in several ways:
- It must ensure the use of the allocated spectrum and verify that the femto-cell is not transmitting out the corresponding frequency band.
- Moving of residences must be managed properly, as this could develop some communities with a lot of interference by the accumulation of femto-cells nearby.
- It must be noted, that traditional planning techniques such as frequency reuse have no sense because the user is who installs the femto-cells.
On the other hand, some problems were found in the femto-cell implementation in areas where there is a Wi-Fi network, in [1], the authors comment some cases where the FAP experiences difficulties in transferring data, even in voice services.
References
- Vikram C, Jeffrey GA & Alan G. Femtocell Networks: A Survey. IEEE Comunication Magzine (2008) 46: pp. 59-67.
- G DLR, A V, D L & Jie Z. Access control Mechanisms for Femtocells. IEEE Communications Magazine (2010) 48: pp. 33-39.
