Smart RAN for 4G – Compact BTS, Metro-Femto & ORI

8/8/2019 Smart RAN for 4G – Compact BTS, Metro-Femto & ORI

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Smart RAN for 4G – C

HARISHVADADA.WORDP

mpact-BTS, Metro-Femto & ORI

ESS.COM LTE & WIM

8/31/2010

| Harish Vadada

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2www.harishvadada.wordpress.com – Please share and give me feedback – via my blog!

As we move towards 4G there has been a trend in

the radio access network (RAN) architecture of

simplifying it, making it more compact and flat. The

primary motive has been to enable mobile

operators to maintain control on their network

costs, while they deal with improving coverage and

capacity. However, the explosion in data traffic

volumes, due to smart phones like the iPhone,

have thrown a spanner in the works for operators

to keep tabs on CAPEX/OPEX costs while they try and keep up with incessantly exploding mobile data

demand from burgeoning smart devices, applications, and changing user behavior. This calls for a new

architectural paradigm that optimizes existing cell site infrastructure, most of which is macro layer

enabled, but at the same time introduces new network layers at the micro-, pico- and femtocell level,that can effectively complement the macro layer.

A new type of base station - the compact BTS along with Femto in the outdoor implementation has also

entered the market, further reducing footprint and power consumption, while retaining the

performance of macro BTSs. Let us explore these concepts and value proposition that we see for 4G

deployment –

⇒ Compact BTS

⇒ Metro-Femto

⇒ ORI - Open Radio Equipment Interface

What is a compact BTS?

It is a single-box base station with radio frequency (RF) and baseband components in a fully integrated,

ruggedized enclosure, mounted at the tower top, adjacent to the antenna array, Lightweight equipment

with a small footprint, Software-defined, single system-on-a-chip (SoC) architecture. It supports multiple

antennas and beamforming with a performance comparable to that of macro BTSs, but with lower

power consumption with no ground equipment, shelter, or air conditioning needed. Only power and

Ethernet (CAT-5 or fiber) cables are required to operate the base station and connect it to the backhaul.

The compact base station is scalable platforms that can fit into multiple site classifications, ranging from

picocell to microcell and macrocell applications. Each site has its own specific equipment characteristicsthat are required for that specific site. Site-specific

classification scheme comes from a set of

requirements, such as cell size, max subscribers,

total required site capacity, and so forth. These

requirements drive the definition of the number

capability of a suitable Compact BTS for the type of

site, e.g., the RF output power, which is largely

determined by site location and targeted cell size.

Finally, the capability set then determines suitable




Compact BTS specifications, such as type of PA, heat dissipation, physical form factor and so forth.

Traditional macro sites are on rooftops or at a self-supporting site that has a tower mast installed with a

cabinet enclosure and is the most common site classification. Macro sites typically have the basebandand radio units enclosed in a cabinet enclosure with the antenna on at the top. This architecture is being

transformed with the introduction of remote radio heads (RRH), which combines multiple elements of

the RF portion of the base station in a single box. Typical RRH consists of the LNA and the Power

Amplifier, TDD Switch or Duplexer, Up and Down Converters, Analog to Digital and Digital to Analog

Converters, I/Q Optical Interface, and some degree of OA&M processing. RRH typically supports a single

sector and attaches onto the tower mast adjacent to the antenna, and connects to the baseband at the

bottom of the tower enclosed in a cabinet connecting with a fiber optic cable. Compact BTS

architectures can allow for the RRH to be combined with a baseband processing unit in a single passively

cooled unit, eliminating the need for a shelter or cabinet enclosure at the bottom of the tower bringing

additional savings on the site and further improving performance.

Metro-Femto and case study of Roke




The pictorial above is the main driver for most operators to go Femto – reduction of churn and Value

creation! The reduction in churn contributes favorably to the value created by the basic value

proposition. Some operators have reported reductions as high as 50% for FMC propositions similar to

femtocells. In reality, after an operator adjusts for the percentage of subscribers adopting femtocells thecomposite change in churn is modest, although the impact is significant among femtocell users. The

impact of churn is greatest driver for any operator as this will drive the bottom line up. Femtocells will

now be deployed in the metro areas to ease the traffic offload from macrocells as well to provide indoor

solutions.

Femtocells may also be used to serve sparsely-populated rural areas that are conventionally thought of

as uneconomic to install a cell phone tower. Femtocells can now serve as "instant economical

infrastructure" to help emergency services or rural residents who are just fed up getting the run around

from their local carrier or cell phone tower companies. Getting the attention of carriers to install new

cell phone towers has been the frustration of many wireless customers who live in remote areas.

Femtocells can now provide an economic alternative to ugly and expensive cell phone towers that oftenrequire multiple carriers piggybacking upon a new development site.

Roke Manor Research a Siemens’ company has developed a Wide

Area Coverage Femtocell capability. Using picoChip's technology as

the development platform, Roke's reference design has a 40km

range which delivers more than many times the area covered by

most other femtocells. It is also the first to support full mobility at

speeds of up to 120 kilometers per hour, allowing mobile users to

travel while connected to the base stations. The femtocell will

support up to 12 simultaneous users, with Release 5 HSPA.

Femtocell base stations offer a low cost and low power solution for

implementing any network. However, they are only suitable for

short range communications of around 200m and as such are ideal

for home networks. Roke, however, can now offer all the benefits of

a femtocell with an enhanced range of up to 40km. In essence, the

Roke modifications permit a macrocell performance in terms of range and mobility within a fetmo

hardware platform. Benefits of Roke's modified femtocell base-station include:

Low Power Consumption

Range up to 40km

Support of 16us Delay Span

Mobility up to 120km/hr with 12 users IP Connection to Network

Circuit Switched Voice Support

ORI – Open Radio Equipment Interface




In distributed base station architecture the radio base stations

consist of a BaseBandUnit (BBU) and a Radio Frequency Unit (RFU),

which usually is a Remote Radio Head (RRH). Current interfaces

between BBU and RRH are provided in a “semi proprietary” nature,

although based on industry standards like CPRI or OBSAI. In order to

gain flexibility operators are looking for distributed base station

architectures with separate BBUs and RRHs. In order to gain

interoperability, BBU and RRH preferably should interconnect via an

open BBU-RRH Interface (ORI) for flexible combination from

different vendors.

Naturally operator networks are subject to change over time and

may require to interface equipment from different vendors too, due

to various reasons:

Mergers or acquisition of operators with different vendor equipment may cause the

necessity to interface equipment from another vendor

For flexibility reasons operators may want to interface equipment from different

suppliers

Termination of a product line from a certain vendor may force an operator to introduce

equipment from another vendor

All above cases are assuming, by avoiding replacing the whole equipment chain i.e. BBU&RRH, at least

parts of the past investments can be saved.

Due to an open interface between BBU and RRH only those parts need be exchanged subject to afunctional/hardware enhancement. As just a limited number of parts need to be exchanged, valuable

resources/commodities may be saved too and certain ecological aspects may be claimed

additionally. For LTE and utilizing the SON (Self Organizing Networks) capabilities, an open Interface is

preferred for plug and play capabilities.

ISG ORI is a direct result of requirements work undertaken by the NGMN Alliance, in their OBRI (Open

BBU RRH Interface) project. The ISG is strongly supported by the NGMN Alliance. Leading mobile

network operators and telecom equipment vendors have agreed to become founding members of the

ISG. The current members and participants of the ISG are: Alcatel-Lucent, AT&T Global Network

Services, Deutsche Telekom, DoCoMo Communications Labs Europe, Ericsson, FreescaleSemiconductors, Fujitsu Laboratories of Europe, Huawei Technologies, Kathrein-Werke, Motorola,

NGMN, Nokia Siemens Networks, NTT DoCoMo, Radiocomp, Reverb Networks, Rohde & Schwarz,

Telecom Italia, Ubidyne, Vodafone and ZTE. Other companies are welcome to join the ISG, whose first

meeting will take place from 25 to 27 May in Turin, Italy, hosted by Telecom Italia.

Resources: ABI Research, Roke, NGMN

Smart RAN for 4G – Compact BTS, Metro-Femto & ORI

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