More details on NTT Docomo's Xi Femtocell

Japanese operator, NTT Docomo recently published some more details about its Xi Femtocell service. The Femtocell is a dual mode LTE-WCDMA femtocell. WCDMA is mainly used as a CS Fallback option when used with LTE device. In this case if the WCDMA part stops working for some reason then depending on the macro availability, it may hand the UE back to Macro or just keep using the LTE only service.

I could not completely figure out but it also looks like the Femtocell operates in co-channel with the Macro. During the power on, SON algorithms device the codes, the power of the femtocell, etc.

The complete article is embedded below:

W-CDMA/LTE dual-mode Ultra-compact Base Station (Xi Femtocell) from Zahid Ghadialy

Building a Sustainable HetNet - Telus, Canada

Came across this interesting presentation from the LTE World Summit 2013, one from Telus in Canada. The presentation is embedded below but here are couple of things that caught my attention:

One of the issues which is now becoming universal is the need to negotiate with the municipalities and local councils for the right to lamp posts and other street furniture. I blogged this earlier as well with regards to a presentation by EE here. This also encourages for a third party to provide small cells hosting as a service (SCaaS)

Another issue generally faced in case of Hetnets is the Interference management in case of shared carrier. Looks like they may be using a proprietary approach for co-channel deployment and similar approaches are possible with basic SON presence in the network.

Anyway, the complete presentation below:

Building a Sustainable HetNet from Zahid Ghadialy

Metrocell Q&A: Dedicated or Shared carrier?

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.

Figure 6. A dedicated carrier is preferred over a shared carrier

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).

Table 2. Metro cells deployment strategies depend on W-CDMA spectrum and LTE plans

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.