Small cell, also known as femtocells, are small-scale mobile base stations introduced in recent years according to the trend of broadband. They support t FDD LTE and TDD LTE, which can absorb traffic and optimize network quality within the coverage.
The implementation of the LTE base station function by the small base station needs to be connected to the LTE core network, and the data can be transmitted back through the carrier private network and the public network.
The small cell implements the LTE base station function to provide communication services for the LTE terminal, and can be connected to the LTE core network through the carrier private network and the public network backhaul; the small cell network management centrally manages the device; and the small cell security gateway implements data packet encryption. The connection established between the small cell device and the core network is to pass through the security gateway via the security tunnel; the small base station access gateway completes the relay between the small base station device and the core network, and completes the convergence of the signaling plane,reduce the impact of signaling overhead on the core network.
2.Gateway And Network Construction Plan
On the actual operation level, the small base station network management device is a server device, and the small base station gateway device is a network management device, which needs to be installed in the core network equipment room, and is connected to the core network device through the Cat 5 cable (category 5 ) to implement data interaction.
After the device is connected, we need to configure parameters for the gateway. The configuration information is as follows.
|MME/GW IP||Carrier core network IP address|
|Security Gateway IP||IP address of the carrier security gateway|
|MME/GW Interface||Carrier core network interface|
|Authentication method||Certificate (requires CA certificate, certificate and private key); PSK (requires the secret key)|
|IPSEC Configuration||ID of the base station and security gateway during tunnel negotiation IKE integrity algorithm, encryption algorithm, pseudo-random number algorithm and DH Group value ESP integrity algorithm, encryption algorithm and DH Group value Rekey and reauth support IKE fragmentation support|
3 Small Cell introduction
3.1 Product Structure
3.1.1 Hardware Structure
The small base station product divides the hardware into two parts according to the device principle, namely the digital baseband part and the radio frequency part, as shown in the following figure.
1. Digital Baseband Section
The functions of the digital baseband section are as follows:
- Implement FFD-LTE baseband signal processing;
- Support 1588V2 and air interface synchronization;
- Control the indicator lights of the device;
- Implement various interfaces external to the device;
- Support local operation and maintenance and R&D testing;
2. RF section
The RF unit performs filtering and power amplification of the downlink signal, low noise amplification and filtering of the uplink signal, and provides an auxiliary function of temperature calibration.
3.1.2 Software Structure
The software is divided into control plane, user plane and management plane. The functions of each plane are defined as follows:
(1) Control Surface
It is used to implement the signaling functions of the UU and S1 interfaces, including cell establishment, system broadcast, establishment and release of user services, establishment and release of transmission bearers, radio resource management,self-organization and self-optimization.
- RRD: implements the service processing function related to a specific UE in the 36.331 protocol, and implements the S1AP related function in the 36.413 protocol.
- RRS: implements the system broadcast function in the 36.331 protocol.
- RRM: Implements the radio resource management functions described in protocols such as 36.133 and 36.331.
- SON: implement self-starting, self-organization, self-optimization, etc.
- S1AP: Implementing the S1 interface control plane access protocol
(2) Business Surface
The data transmission function used to implement the UU interface mainly includes L2:
- L1C: implements adaptation to different physical layer PHYs.
- MAC: Implement the functions specified in the 36.321 protocol
- RLC: Implement the functions specified in the 36.322 protocol
PDCP: implements the functions specified in the 36.323 protocol and implements the S1AP related functions in the 36.413 protocol.
(3) Management Surface
Used to implement OAM functions.
Transmission of GPT-U and SCTP functions at the network layer.
S1 Transport Layer: Enables the S1 interface to transmit network layer functions, such as GTP-U and SCTP.
4.2.1 Support FDD-LTE base station eNB function
- IP header compression and user data encryption
- MME selection
- User plane data is routed to the service gateway SG
- Paging message scheduling and transmission
- Broadcast information scheduling and transmission
- Measurement and configuration of mobility and scheduling
- Upstream transport layer packet identifier
- Support HeNB related functions
- HeNB gateway GW discovery
- Operation and maintenance function
- Support access to the remote base station management system OMC
- Support for accessing to the near-end network management system
- Other functions
- Support synchronous mode such as air interface synchronization/1588V2 synchronization
3.3 Product Classification
3.3.1 Pico or Femeto Site(Home-type Small Base Station eNodeB )
The home-type small base station is suitable for LTE signal coverage in the indoor small environment, and has strong pertinence. The home broadband can quickly solve the problem of signal coverage optimization, it is with the built-in antenna, plug and play and fast optimization features for solving the no signal site quickly.
|1||Coverage range||500 m2|
|2||Max Radio Out power||100mW|
|3||User capacity per carrier||RRC Connect User 32 RRC Active User 16|
|4||Networking||Self-configuration & Self-optimization|
|5||Backhaul Method||GE Port|
|6||Power Supply||DC 12V Or POE48V|
4.3.2 Enterprise Pico Base Station (eNodeB)
The Enterprise small base station is suitable for LTE signal coverage in the outdoor environment. The power level can be customized according to the coverage range, and then the optimization problem of signal coverage can be quickly solved through the home broadband or the private network line according to the site conditions. It is optional for built-in antenna or external antenna for fast installation.
|1||Coverage Range||1000 m2|
|2||User capacity per carrier||VoLTE User：32 Active User：32 Connected User:64|
|2||Max. Radio Output power||200mW|
|3||Networking||Self-Configuration $ Self-Optimization|
|4||Backhaul Method||GE(g-Ethernet) Port or SFP(fiber optical port)|
|10||Size（H×W×D）||200 x 200 x 62mm|
4.3.3 Distributed Pico Cell Site
The distributed small base station is suitable for indoor large-area environment LTE signal coverage, and can customize the power level according to the coverage range, and can select the home broadband or the private network line to quickly solve the signal coverage optimization problem according to the field conditions, and the built-in antenna or external antenna can be selected for quick optimization.
The equipment consists of three parts, namely the distribute cell site (BBU), the switch and the RRU. They can be connected and powered by the Category 5 or Super Category 5 lines. The radio frequency function of the sub-machine forms a small base station network to absorb the larger area LTE service.
|1||Coverage Range||20000 m2|
|2||Max Radio Output Power||250mW|
|3||Networking||Self-configuration & Self-optimization|
|4||Backhaul Method||GE Port，SFP|
|6||Power Consumption||BBU: 20W; Switch (Bridge): 20W，RRU 25W|
4 Small Cell Opening Parameter Configuration
After the installation of the small base station equipment is completed, the data is configured according to the following process, and the installation can be completed.
5.1 Login in Configuration Interface
The base station can dynamically obtain an IP address through DHCP, or assign a static IP address according to the operator’s plan.
If the IP address is dynamically assigned through DHCP, you can use the MAC Scan tool to query the IP address obtained by the base station.
If the operator is planning, assign a static IP address; the process of configuring a static IP address is as follows:
PC connect the Small Cell,
Configure the IP address of the PC to be 192.168.200.100/24.
Username: admin, Password: Pico@2018
Configure the network parameters of the base station.
Address Type is configured as Static; The IP address and mask are configured according to the actual plan.
5.2 Set Transmission Data Configuration Transfer Data
On the Management->Cell page, configure S1SigLinkServer as the IP address of the EPC/signaling gateway.
5.3 Configuring Wireless Data
On the Management->Cell page, configure wireless data:
Duplex Mode: FDD PLMNID: 46011
TAC: 51588 CellIdentity: 211362078
CandidateARFCNList (frequency point): 100 (only need to configure the downlink frequency point, the uplink frequency point base station automatically calculates)
CandidatePCIList: 0..63 (Base station through PCI self-configuration function, select available PCI from 0 to 63)
DL Bandwidth: 100 (the number of PRBs corresponding to 20M bandwidth, 75M bandwidth is 75, 10M bandwidth is 50, and 5M bandwidth corresponds to 25)
UL Bandwidth: consistent with DL Bandwidth
ReferenceSignalPower: -14 (reference signal power, up to -14, corresponding to 50mW)
After the configuration is complete, click Submit.
After the configuration is submitted, the base station takes effect in the restart mode.
After the restart is complete, you can try to access the terminal.