Femtocell tutorial-basics, architecture, interference, handover, security, testing, manufacturers
This page on Femtocell tutorial covers femtocell basics including network architecture, handover, security, interference, femtocell testing and femtocell manufacturers.
As we know wireless signal become weak when it travels from its initiation till reception. This happens due to signal path loss as well as due to interference. Hence it is required to be boosted or amplified to obtain better coverage. The other option is to have smaller internal base stations within the home or office premises which will take care of providing boosted cellular signal to extend the coverage. This small base station is known as femtocell. The femtocell will interact with femtocell gateway which interfaces with the cellular mobile operator infrastructure. This backbone infrastructure will be connected with internet.
For different technologies different femtocells have been developed to provide the respective boosted signal to the users or subscribers or CPEs. Hence wimax femtocell, 3G femtocell and LTE femtocell are available as per wimax, UMTS and LTE standards respectively.
Femtocell provides benefits to both the users and operators. It provides improved performance to the users and extra money to the operators due to addition of extra services.
3GPP release 8 specifies 3G femtocell(UMTS femtocell) and 3GPP release 9 specifies LTE femtocell specifications. Please note that UMTS femtocell is known as HNB and LTE femtocel is known as HeNB. HNB refers to Home NodeB and HeNB refers to Home eNodeB or Home eNB.
ITU-R IMT family have defined femtocell standards. They are as follows.
• 3GPP standard for HNB for WCDMA and TD-SCDMA. Both TDD and FDD topologies aee defined in the specifications.
• 3GPP standard for Home eNode-B(HeNB) for LTE, both TDD and FDD are specified.
• 3GPP program for femtocells as per CDMA2000 1X, 1X EV-DO, CDMA2000
• WiMAX Forum program for femtocell compliant to IEEE wimax standard.
Femtocell network architecture
Figure-1 depicts high level femtocell architecture irrespective of any standard based technology.
As shown femtocell system consists of following elements.
• Femtocell device• Router(DSL or Cable)• ISP link• mobile operator network• cellular tower
Based on the technologies different femtocell network architectures exist viz. wimax, UMTS(3G), CDMA2000, LTE etc. The architecture consists of various femtocell interfaces with the other network system elements. Basically there will be two main elements femtocell and gateway. Femtocell provides connectivity with various subscribers/users. Gateway is the interface between femtocell and the network.
For example, UMTS network consists of Home NodeB (HNB) i.e. femtocell and Home NodeB Gateway. The femtocell architectures of 3GPP and 3GPP2 are different. 3GPP is the standardization body behind UMTS which is 3G upgradation to GSM. 3GPP2 is the body behind CDMA2000 which is 3G upgradation to cdmaOne network. This is the difference between 3GPP and 3GPP2. Refer Femtocell Architecture➤➤
As shown in the figure-2, the femtocell network consists of femtocell in the office or home or apartment premises and macro cells in the outside.
Based on this, there are various types of femtocell handovers. Macrocell refers to the region usually covered by standard cellular network.
• From macrocell to the femtocell
• From femtocell to the macrocell
• between femtocell to the other femtocell in the region
Femtocell provides hard handover which is automatic as well as seamless between home network(such as wifi) and cellular network(such as UMTS or LTE) in use. Refer Femtocell handover➤➤.
As we know interference is usually caused due to high power of nearby channel interfering into proper
functioning of the desired channel as expected. To overcome this, there are many solutions.
One such solution is limiting the transmitter power
enough to keep the transmission within the coverage as designed.
Refer Femtocell interference➤➤ and
Femtocell timing and synchronization➤➤
Though wireless system provides better security compare to the wired networks. The security of femtocell is threatened due to various probable security aspects such as intrusion, hacking and so on. In femtocell, the security lies with the protection provided to the IP packets travelling between network elements. IPsec protocol provides security in femtocell based network.
Based on the various stages of femtocell development, there are various tests which are essential to be performed. The tests are related to verification, conformance, regulatory, manufacturing and interoperability of femtocell devices. In all the tests, transmitter and receiver modules are required to be tested. All the protocol stack layers are required to be tested based on the test type. The protocol stack layers are different based on technologies. Femtocell testing helps avoid any functional and performance related issues. Refer Femtocell testing➤➤
Following are the femtocell developers or femtocell manufacturers.
• Gemtek, taiwan
• Tecom, Taiwan. It is one of the ODM of Ubiquisys.
• Zyxel, Taiwan
• C & S microwave
Also refer LTE femtocell vendors page.
Femtocell tutorial related links
RF Wireless Tutorials
Refer following RF and wireless tutorials in addition to femtocell tutorial described on this page.
GSM TD-SCDMA wimax LTE UMTS GPRS CDMA SCADA WLAN 802.11ac 802.11ad GPS Zigbee z-wave Bluetooth UWB IoT T&M satellite Antenna RADAR RFID