Why IP based Pico-Cell & Nano-Cell Solution?

Why IP based Pico-Cell Solution?

Why IP based Pico-Cell Solution?

The concept of “Pico-cell” solution is well defined in the 3GPP association and well known in the mobile industry. The “Pico-Cell” provides GSM operators a simple solution for enhancing capacity and coverage levels in hotspot “indoor” areas with minimal interference on the micro/macro “outdoor” coverage.

On the other hand, mobile vendors didn’t give the Pico-Cell enough focus due to commercial reasons and instead preferred to offer their high capacity products in the micro layer along with a Distributed Antenna System (DAS) to provide the necessary coverage levels within a building and a high capacity backhaul solution (fiber, copper or microwave) to carry the generated traffic. Such solutions in addition to being costly are very involved and require highly skilled resources, a lot of permissions and as a consequence a lot of time.

There are some deployment scenarios that don’t justify the investment in a complete DAS or in high-capacity backhaul solution.

In some other cases, the urgency of the project doesn’t leave enough time to even deploy a DAS.

By providing a pico-cell with IP connectivity mobile operators can immediately provide hotspot coverage and capacity where required with minimum cost and time. The direct cost savings come from backhaul savings since a pico-cell based on IP backhaul can utilize spare capacity in existing broadband connections. In addition, the size of such a solution prevents the deployment team from going through the time consuming process of permitting and installation thus enabling mobile operators to provide coverage on time.

This solution is expected to make an appeal for mobile operators (especially startups) in countries where broadband penetration is moderate.

ip.access has a strong reference which includes operators like: T-Mobile USA, Smart in the Philippines, Telfort (now KPN) in the Netherlands and Eurotel in the Czech Republic.

Why IP.Access NanoGSM Solution?

Ip.Access provides a unique solution for the IP based Pico-BTS system called nanoGSM. In the following section more details will be given about the nanoGSM solution but we can highlight the key features and advantages for this system that differentiates it from other solutions.

Key features
■ Rapid installation using existing IP infrastructure
■ Standard radio interface compatible with all GSM handsets
■ Multi-TRX capability to support large numbers of users
■ Typical indoor coverage up to 125,000m2
■ Excellent data rates with GPRS support
■ Single10/100 Ethernet connection incorporating power, traffic and signaling
■ Smallest footprint in the industry

Applications
■ Dedicated coverage for SME premises with DSL based link
■ In-building capacity and coverage for large corporate offices
■ Stand-alone in-fill for shopping malls, airports or undergrounds
■ Delivering GSM access on ships, airplanes and rural areas

NanoGSM System Overview

The nanoBTS is a single-TRX indoor pico-class BTS offering a standard Um radio interface to GSM mobiles. Whereas the conventional connection between BTS and BSC is circuit-based, the A-bis connection between the nanoBTS and the BSC is carried over an IP network using proprietary A-bis over IP technique. Standard (E)GPRS service is also offered on the radio interface and is similarly transported over IP.

The Circuit BSC performs the normal functions of a GSM BSC. It presents a standard E1/T1-based A-interface to the MSC and a standard Frame-Relay-based Gb interface to the SGSN, allowing connection to conventional GSM/GPRS networks.

The IP network between BTS and BSC can be implemented using a variety of physical links and network topologies. The OMC-R is ip.access’ management system for the nanoGSM system. All components and interfaces are described in more detail in the following sections.

A variety of other operational scenarios are possible, for example an operator that only provides indoor coverage may negotiate national roaming agreements to provide its customers with service beyond the range of the indoor network. Another example is to use the nanoBTSs to provide localized coverage in isolated areas with no GSM coverage.

Often the nanoGSM BSC will be located at the same site as the MSC. This allows the A-interface connections to be short-range, with the A-bis links carried over some form of IP access network. Conversely it is possible to locate the BSC remotely from the MSC, perhaps co-locating the BSC with a cluster of nanoBTSs.

In all cases it is important to note that the interface presented to the GSM handset is entirely standard – no special features are assumed.

nanoGSM™ BSC

The ip.access nanoGSM™ BSC (basestation controller) is a key component in handling and routing traffic between picocellular basestations (nanoBTS™) and an existing Mobile Switching Centre (MSC) as part of an overall GSM network.

The BSC is a modular unit that uses IP connectivity between the nanoBTSs and the BSC and a standard circuit-based A-interface to the MSC. There is also an option to connect into architectures with softswitch MSCs.

The BSC provides channel allocation functions, GPRS support and also controls the power level algorithms and handover procedures for the nanoBTSs. The unit is engineered to have a high level of availability by combining selective redundancy with fast restart capabilities.

The nanoGSM BSC is extremely versatile and allows a wide range of different architectural configurations dependent on traffic densities and the ease of deployment. The nanoGSM BSC is usually co-located with the MSC at the central office. However in cases with heavy traffic usage and multiple basestations in one building, there is the option of placing the nanoGSM BSC at the customer site.

The nanoGSM BSC connects to the nanoBTS over IP using a version of the Abis interface. This gives a wide range of possible IP network configurations for the deployment of the base-stations. For integration into existing mobile network infrastructure the nanoGSM BSC connects to MSC and SGSNs over standard circuit switched E1 or T1 links.

For an all IP based network, the nanoGSM BSC can be integrated with a soft-switch. This gives the opportunity to reduce backhaul costs by routing traffic locally at the BTS, and also reduces the costs associated with the circuit interfaces.

nanoBTS platform

The nanoBTS is an ETSI-compliant GSM pico-class BTS [05.05] available in 900MHz, 1800MHz and 1900MHz band versions (EDGE not available in 900MHz). The full range of 900/1800/1900MHz GSM channels is supported, using the normal 200kHz channel spacing.

The nanoBTS is a single-TRX BTS designed for indoor use (–5C to +45°C). It can be wall or ceiling mounted, having a footprint less than A4 (max dimension 210mm x 280mm x 77mm) and a weight of 2.7kg (139/140 nanoBTS) or 2.0kg (165 EDGE nanoBTS). Maximum transmit power is +23dBm for the 1800/1900 MHz products in GSM mode and +13dBm for the 165 EDGE product operating in 8PSK mode, in line with the pico-class specification. The maximum transmit power of the 900MHz BTS is +20dBm.

The nanoBTS has integrated omni-directional antennas with an option for external antenna connection. The primary physical connection to the nanoBTS is a single Ethernet connector supporting:
■ The A-bis over IP interface
■ Power feed

An additional pair of connectors (the Timing Interface Bus, TIB) allows up to four collocated nanoBTS units to operate as a single 4-TRX BTS. Each nanoBTS retains its own Ethernet connection for signaling and traffic, with the TIB providing synchronization of frequency and frame number.

The nanoBTS typically uses a Combined BCCH with optional CBCH, but a separate SDCCH/8 channel can also be configured. Other timeslots may be used for TCH or PDCH. Unlike a conventional BTS, the nanoBTS incorporates a highly stable frequency reference so that it does not need to recover a timing reference from the A-bis connection. This greatly increases the flexibility of backhaul connection.

OMC-R
The OMC-R (Operation and Management Centre (Radio)) is ip.access’ network management solution. The product is composed of two components: a server that connects to each BSC in the network and multiple clients that connect to the server in order to work with management information. The Client has 2 main functional areas: Alarm Management and Configuration Management. The Configuration Management functions provide access to all BSS objects and attributes in a MIB-structured presentation.