The premise of the vendors is that femtocells should require no radio planning. Since operators do not, by and large, know where any individual femtocell will be deployed, they cannot reconfigure their macro network to account for this. There is substantial research and trial work ongoing to reduce the impact of the femtocell on the outdoor macrocellular network. Since the signal levels are very low power and do not easily penetrate walls, little is radiated outside the premises where they are located. Some femtocells also “listen” to the external macrocellular network to pick a frequency which will cause minimum interference.
Operators do not need to negotiate with landlords for site acquisition. Instead, they need to make a compelling and attractive commercial offer to their customers who will host it themselves. There are no ongoing running costs per site for site rental, power or backhaul transmission – the last of which increases substantially for high volume data traffic. Again, the intention is that femtocells are “self configuring” and do not require any specific parameters to be downloaded. The femtocell should directly connect to its femtocell controller (whether RNC, UNC or other system) and receive and specific configuration information automatically. Vendors intend that self-installing femtocells will automatically configure themselves without operator intervention. However, if there are problems, operators will require excellent diagnostic tools to be available to their customer care teams to identify the issue and resolve it.
Whilst there are no project management systems to control the rollout of new cellsites, or field teams to manage the installation work, there will be a need to manage despatch of the equipment to the customer. If this is done on a rental basis, then the assets will need to be tracked and recovered at the end of the contract period, similar to a rental TV or Set Top Box. If the cost of the femtocell is low enough, then it is unlikely to be worthwhile to do so.
Transfer of femtocells from one operator to another. It is very unlikely that this will be encouraged by operators in the first instance – it is more likely to be cheaper to provide a replacement unit configured for the new operator. There would need to be standards enforcing interoperability in the same way that any mobile phone can be used on other networks (of the same technology standard) – the benefit being ability to use the device around the world and the drastically reduced cost from mass production. For femtocells there is less interest/commercial pressure to do so, with even the system architecture not agreed.
Femtocell Installation issues.
It is likely that operators will need to invest in good technical support to install and maintain the femtocells. Often non-technical customers will be involved, so the procedures and diagnostic utilities need to be very straightforward. Indicators on the femtocells are likely to be required to show:
- Broadband signal connection active and online
- Connection into the operator’s network active and online
- If a mobile phone is “camped” on the femtocell (see below)
- When a voice or data call is active
It can be difficult to know if a mobile phone is “camped” on a specific cell, since this is determined only by the mobile when an active call is made or received. The mobile network is only aware of the “location area” of each phone. When a phone moves to a new location area, or after a configurable period, a location update message is sent to the network so that the phone can be contacted for any incoming calls. A paging message is broadcast through all cellsites in the paging area in order to connect to the desired phone. One method may be to configure each femtocell as an individual paging area – this would ensure that the femtocell knows when the mobile phone enters the home zone (because a location update message would occur) – but there may be impacts on the sizing capacity of the MSC and SGSN which initiate the paging messages, as well as the potential for increased numbers of location update messages to the network.
Customers can then be “walked through” the self installation of femtocells, ensuring that the lights come on in sequence. A straightforward installation should simply involve connecting the box to the broadband DSL line and power. If it is GPS equipped (to ensure only used where spectrum licence permits), then it needs to be located near to a window. For femtocells which also include WiFi and/or PC connections, then some configuration using an onboard configuration website may be required. However, it is expected that:
DHCP should be enabled for all wired and wifi connections (this may require reconfiguration depending on the DSL provider’s DNS and other settings)
WPA should be enabled for wifi. This may require reconfiguring the WPA clients on each laptop. One of the benefits of using mobile broadband rather than WiFi may be the more automatic security setup.
Self registration with the operator’s network would require it to be a totally automatic process. One method used by another similar telco system involves a two stage registration process:
a) The femtocell has standard, common software installed in the factory
b) On first powerup, it connects to the vendor’s website, sending its serial number.
c) The vendor’s website downloads any firmware and security updates to the device
d) The vendor’s website uses the serial number to identify the mobile operator which owns it. It then redirects the femtocell to contact the mobile operator’s servers.
e) The femtocell registers with the mobile operator’s network, and receives and operator specific configuration (eg operating frequency, max power level, cell id, paging area etc)
f) The mobile operator network also downloads the list of phones allowed to use the femtocell
a.So that a tone or other indication can be given to the customer when making or receiving a call on the cell, to show that lower billing rates apply
b.To restrict use of the femtocell to authorised phones where the customer requests it.
g) The femtocell is authorised to transmit by the mobile operator’s network and becomes part of the live operation.
h) The customer can make or receive calls using the femtocell.