Cellular Communication Networks and Standards by Wei Jiang & Bin Han

Author:Wei Jiang & Bin Han
Language: eng
Format: epub
ISBN: 9783031578205
Publisher: Springer Nature Switzerland

7.3.10 Heterogeneous Network/HetNet

The network architecture has been transformed due to the increasing need to deliver high data rates to a large number of mobile users. In cellular networks, to achieve high system capacity, various techniques are employed. These include employing advanced radio transmission methods to enhance spectral efficiency, acquiring more spectral resources, or deploying denser network nodes. In a traditional homogeneous network, cell splitting is used to decrease cell size and increase capacity, but this requires network re-planning and system reconfiguration. Additionally, the traffic demand is not evenly distributed. To address these challenges, LTE-Advanced introduced Heterogeneous Networks (HetNets), which consist of cells of different sizes, transmit powers, coverage areas, and hardware capabilities, such as macro, micro, pico, and femtocells. Low-power, cost-effective base stations are added to macro-cell networks as underlying nodes to provide high capacity in areas with high demand or to fill coverage gaps, both indoors and outdoors.

Ideally, if there are sufficient radio resources available, different frequency bands can be allocated to different cell types to avoid interference. However, due to the increased traffic demand, it is not always possible to allocate a dedicated carrier for small cells. As a result, heterogeneous cells must coexist and operate on the same set of frequencies, even if they overlap geographically. One of the major challenges in deploying a heterogeneous network is managing inter-cell interference. To tackle this issue, 3GPP established a work item focused on ICIC, which was later evolved to eICIC. LTE-Advanced utilizes carrier aggregation to support the deployment of such a heterogeneous network. In this approach, cross-carrier scheduling is employed, allowing control signaling to be transmitted on a shared component carrier. This helps prevent interference on control channels between the macro-cell layer and the small-cell layer.

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