From Alcatel-Lucent techzine:
SHOULD I USE DEDICATED OR SHARED CARRIER?
While both dedicated and shared carrier solutions can be built, a selective dedicated carrier is always preferred over shared carrier for metro cell deployments, especially in outdoor environments where macro cell signal levels will be higher (Figure 6):
- With dedicated carrier, the MNO reserves a carrier for the exclusive use of metro cells in geographies that have been specifically targeted as needing extra capacity. In all other areas this same carrier may be used by macro cells. The use of a dedicated carrier avoids interference with the macro cell, which enables metro cells to cover wider areas and to absorb a larger amount of traffic off the macro network – greatly improving the TCO.
- With shared carrier deployments, metro cells use one of the same carriers assigned to the macro layer, which would normally have one or more additional dedicated carriers. The coverage range and offload effectiveness of metro cells deployed with shared carrier are lower than those using dedicated carriers. Additionally, metro cells cannot be placed too close to high-power macro cells with this type of deployment, as represented by the red exclusion zone in Figure 6.
TURNING ANSWERS INTO STRATEGY
Each MNO’s metro cell deployment strategy should be based on their W-CDMA spectrum holdings and LTE launch timing (Table 2).
Spectrum-rich W-CDMA MNO launching LTE early (2011 – 2013)
MNOs with rich W-CDMA spectrum holdings and launching LTE early should deploy W-CDMA metro cells to both indoor locations and traffic hotspots using a dedicated carrier, while also deploying LTE metro cells to traffic hotspots. To help offload the macro network in hotspots, the MNO may also consider deploying Wi-Fi-integrated metro cells.
Spectrum-rich W-CDMA MNO launching LTE late (2013 – 2015)
Operators with rich W-CDMA spectrum holdings, but launching LTE late, should also deploy W-CDMA metro cells to both indoor locations and traffic hotspots, using shared carrier. To help manage interference and avoid handoffs, traffic should also be segmented, so only HSPA data traffic is offloaded to the metro cells in hotspots. These MNOs will also benefit from deploying Wi-Fi access points that are integrated with the metro cells to help further offload the macro network.
Spectrum-poor W-CDMA MNO launching LTE early (2011 – 2013)
MNOs with poor W-CDMA spectrum holdings and launching LTE early should deploy W-CDMA metro cells in shared carrier to indoor locations only, while also deploying LTE metro cells to traffic hotspots for extra capacity. If the MNO has a Wi-Fi access network, these sites can easily be used for the deployment of metro cells by simply swapping out the legacy Wi-Fi access points for Wi-Fi-integrated metro cells.