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Connected world: a changing wireless paradigm

Inherently we the humans always want to get connected by phone, email, social media, Television, radio with the rest of the world. Things are changing fast now it’s about connected devices, appliances, automobiles, transport systems and even the plants. Anything can be connected will be connected. Anything can have a chipset will have a chipset.

When we talk about the connectivity, wireless comes to our minds.

In wireless land scape there are several technologies having different set of advantages and disadvantages. Broadly the wireless technologies divided into WAN, MAN, LAN, PAN. We have a distance Vs throughput with application comparison chart located below.

 

Wireless Standards Primer

Traditionally 3GPP standard based technologies dominate in the WAN and MAN technology landscape. In MAN segment, WiMAX is used to some extent, which is an IEEE standard (IEEE802.16 *) based technology. It did not get traction world-wide. In the wireless LAN and PAN segment IEEE standards based technologies are very common. Bluetooth which started from Ericsson initially was accepted by IEEE and incorporated IEEE802.15.4 features. Zigbee is very popular in sensor networks, connected homes and smartgrid home area network segment. It is built on IEEE802.15.4.

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Categories: Broadband, LTE Tags: , ,

Telecom Evolution: Impact of Economic Cycles, Consolidation & Managed Services

Source: Wall Street Journal

 The other day when I saw this graphic in WSJ it reminded me, of a time when I was starting out in the field of Telecom as a junior engineer, the world look so brilliant. I could go work for so many Operators – wireless and wired! The world was going wireless, GSM was new to India and Industry captains were predicting a multi-fold growth. While in the US it was CDMA vs GSM – two very strong contenders that were changing the way the world was communicating, while the cola wars were dominating the rest of the news and Billy Joel singing – “we didn’t start the Fire” !  

  
 Economic Cycles:

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3 key enablers for Broadband Wireless

Wireless today at a crossroads and has become a key enabler of future consumer products, with potential applications ranging from high bit-rate video conferencing and movie viewing to simple ‘house keeping’ tasks in domestic appliances. Radio systems have moved toward forming heterogeneous wireless networks (hetnets), collaborations of multiple radio access networks, which in some cases operate different radio access technologies, such as second- and third-generation cellular RATs, IEEE 802.x wireless standards, and so on. On the other hand, multimode reconfigurable user devices with the ability to choose among various supported RATs have become a reality, and devices and networks with dynamic spectrum access capabilities, allowing real-time sharing of spectrum resource usage among different systems, are a part of the radio eco-space today.

Every decade brings changes to the way wireless is delivered to the users, and this decade shall belong to the indoor coverage and related services for wireless.  I call them service ‘enablers’, the means to deliver a positive experience to users.  While the 4G standards battle rages on for LTE vs. WiMAX, only the ecosystem will decide which will the dominant technology for the next decade. Whichever technology wins, these enablers will be omnipresent to delivery these technologies.  We are at a true convergence for wireless where telecom meets the smart grid, smart home, and where networks become a service.  The aims of the Wireless Enablers work area are, to develop technologies to support interworking of networks and efficient and effective use of spectrum for inter-RAN communications. Enhanced operation of data delivery mechanisms (performance and mobility), reduced complexity in processing.

Femtocells

The great outdoors for cellular wireless has been conquered. RF has limitations for delivery of wireless indoors, and there is a limit to the number of sites that any operator can deploy, with zoning and other FCC/FAA restrictions in place. Though repeaters and DAS systems have been around for a while now, but their place in the world is relegated to where no Pico/Femto cell would be able to provide the capacity and coverage like inside tunnels or casinos etc. Pico cells have filled in the coverage holes for operators in a big way and have been around for a while, but that entails an OPEX for the operator (power/backhaul) and can only plug some indoor coverage holes for the operators. The big push would be for Femto cells, where operators have a big advantage of getting coverage without any OPEX. Both the 3GPP (LTE) as well as WiMAX Forum have published the Femto standards, and are aggressively pursuing its deployment.

By 2012, there will be 36 million shipments with an installed base of 70 million femtocell serving 150 million users.

Source: Pico Chip

LTE Femto Architecture

LTE HeNB – Release 8

Femto-cells or Home Node Bs have been a hot topic for quite some time since they offer benefits such as providing:

• Significant offload of traffic from regular base stations;

• Full coverage and high speed transmission at home;

• Better link quality; lower transmit power, higher performance;

• A single mobile device serving all purposes for the customer;

• Improved customer relations for the operator.

In 3GPP terms, LTE femto-cells are called Home Node B’s for HSPA and Home eNode B’s for LTE. With increasing LTE terminal penetration and fixed-mobile convergence, the expected demand for LTE Home eNodeBs is likely to provide attractive services and data rates in future home environments.

WiMAX Femto Architecture


WiMAX Forum Global Congress, Amsterdam – June 17th 2010 – The WiMAX Forum and the Femto Forum announced the publication of the first WiMAX™ femtocell standard allowing vendors to start developing standardized femtocells and associated network equipment based on the IEEE 802.16e radio interface and profiles. The WiMAX Forum aims to start certifying compatible products in early 2011 to guarantee efficient and effective interoperability between different vendors’ access points and core network equipment.

WiMAX femtocells cost-effectively enhance coverage and capacity inside buildings and in small outdoor areas as well as supporting advanced new services. The specifications incorporate a security framework that allows WiMAX networks to support a large number of access points via standard commercial IPSec based security gateways. This phase of specifications also contains simple Self Organizing Network (SON) capabilities to allow automatic configuration of large numbers of femtocells. Future revisions will further enhance the SON capabilities to standardize automatic interference management between femtocells and macro base stations.

Game changers

SoftBank Corp. has started offering femtocells for free in Japan as it ramps up its national service this year, a move that could spur other operators to adopt the same model for the small home base stations.

Not only are Softbank’s femtocells offered for free, but so is the ADSL connection, when customers sign up to a two-year contract. Another twist in Softbank’s strategy is that the access points are configured for open access, which means that any Softbank subscriber within range of a femtocell can use it. Most femto services today are offered on a closed access basis, which allows only registered users to use the access point.

SDR – Software Defined Radio

Software Defined Radio (SDR) is a radio technology implementation using software, which will become ubiquitous and a key enabling technology for reconfigurable, reprogrammable processing devices for Radio Access.  SDR is the centerpiece in the development of multi-band, flexible and smart base stations that can costeffectively evolve as the technology advances. The classic definition of SDR is having arrays of general-purpose processors running virtually all functions in software.

SDR will help in efficient radio resource allocation for opportunistic communications, Support co-existence of devices and standards and multi-mode terminal to concurrently support multiple data delivery mechanisms with enhancements to standards to improve capability.

SDR platform can simultaneously support multiple air interfaces on one frequency and is particularly focusing on the 900MHz GSM band, which many European nations are allowing to be reused for newer technologies, especially for rural coverage. Its Multi-carrier Transceiver (MC-TRX) radio module can be used to upgrade base stations, continuing to support 900MHz or 1.8GHz GSM, and add support for HSPA or LTE as required, or when the regulator permits.

An SDR solution can be leveraged for:

  • Redefining the base station from one radio technology to another
  • Deploying multiple radio technologies in one base station simultaneously
  • To target GSM refarming, and its radio (BBU) swaps for technology upgrade paths
  • CAPEX would be saved as there will be no need to acquire new sites

This is a silent revolution that is taking place among the Chipset manufacturers, Infrastructure Vendors and operators that will have far reaching consequences for adaptation of efficient technologies and help re-use the spectrum.

SDR Ecosystem

ZTE was one of the first vendors to launch a SDR base station that can be upgraded to LTE through a baseband add-on and a software upgrade. Several other vendors have followed and are now launching – or have already launched – SDR base stations. The form of SDR implementation in base stations varies and each vendor may have chosen a different level of commitment for software reconfigurability. ZTE and Huawei are the only vendors that support dual mode GSM/UMTS operation in their base stations, ZTE having released the platform first. However, dual mode SDR deployments have been limited to date and are now slowly entering the market.

M2M – Machine-to-Machine

M2M or Machine-to-machine communications is the next biggest boom for the wireless operators. There are now more than five billion connections worldwide. In many regions, penetration exceeds 100%, where there is more than one connection per person in the country, and for operators to get more net adds and to grow they have to look towards this segment. One of my first experiences was deploying SCADA devices in the Gulf of Mexico on Oil Platforms which sent readings to the control centers via GPRS/EDGE networks. But things have changed from then to now, where Air Interface has become more robust and the ‘data pipe’ has become fatter and more self sustaining. And On-Star devices on vehicles have become standard, for driver safety and tracking.

M2M has been around for a while but the cost, performance breakthroughs have come closer to reality, and the standards have been formalized. With a mobile voice market close to saturation in the all over the world, many operators are searching for new sources of revenue.

Key Elements of M2M Architecture

M2M Devices

- A device capable of replying to requests for data contained within those devices or capable of transmitting data contained within those devices autonomously.

M2M Area Network

- Provides connectivity between M2M Devices and M2M Gateways. Examples of M2M Area Networks include: Personal Area Network technologies such as IEEE 802.15, SRD, UWB, Zigbee, Bluetooth, etc

or local networks such as PLC, M-BUS, Wireless M-BUS.

M2M Gateways

- Use M2M Capabilities to ensure M2M Devices inter working and interconnection to the communications network.

M2M Communications Networks

- Communications between the M2M Gateway(s) and M2M application (server). Can be further broken down into Access, Transport and Core networks. Examples include (but are not limited to): xDSL, PLC, satellite, LTE, GERAN, UTRAN, eUTRAN, W-LAN and WiMAX.

M2M Applications (Server)

- Contains the middleware layer where data goes through various application services and is used by the specific business-processing engines. A software agent or process by which the data can be analyzed, reported, and acted upon.

All standards organizations led by ETSI are working towards developing common architecture for M2M, as Multitude of technical solutions and dispersed standardization activities result in the slow development of the M2M ecosystem.

Game changers

The leaders in M2M communications in the US market have been the traditionally the GERAN carriers – T-Mobile and AT&T, but Clearwire too has been playing the catching up game with WiMAX nationwide deployments.  And Verizon and Sprint are also working with vendors for device certification and building middleware platforms for M2M services with platform vendors like Jasper Wireless & Sierra Wireless to integrate server and access-network resources. This space shall also be leveraged by the utility power and water companies along with healthcare monitoring service providers. KPN (KPN) a Dutch carrier is using CDMA450 for M2M and has embraced the technology as it pushes heavily into the machine-to-machine space.

Overall all these trends shall make wireless services a part of life, just like how we cannot imagine living without a cell phone in this connected world, so will these three trends influence the way of life in the next decade.

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Categories: 3GPP, Broadband, IEEE, LTE, WiMAX Tags: , ,

Why TDD is the smarter way to deploy Broadband Services

Why TDD is the smarter way to deploy Broadband Services?

With the advent of B3G** technologies, the older method of deploying networks with paired FDD spectrum loses it charm. In the post-Voice centric era of network expansion to capture a market share of data hungry devices, it becomes very essential to squeeze the most out of spectrum. 4G systems are all IP system, but the RF allocations follow the voice-centric approach of earlier generations. While LTE standards allow for either Frequency Division Duplexing (FDD) or Time Division Duplexing (TDD), all initial LTE equipment uses FDD. FDD requires two separate blocks of spectrum—one for each direction. FDD makes perfect sense for bi-directional voice traffic. It makes no sense for data. With the exception of peer-to-peer file sharing, data traffic is very asymmetric. Sending data via FDD means one block of spectrum is fully utilized and the other, equal sized block, is dramatically underutilized, which is an inefficient way for capacity planning.

LTE and TD-Ecosystem

The LTE ecosystem supports both FDD and TDD operation. Fifteen paired (FDD) and eight unpaired (TDD) spectrum bands have already been identified by the 3GPP for LTE. This means an operator can introduce LTE in new spectrum bands, where it is easiest to deploy 10 MHz or 20 MHz to carriers and eventually deploy LTE in all bands.

Operators can launch LTE to match their existing networks, spectrum and business objectives for mobile broadband and multimedia services. LTE in FDD spectrum bands are being deployed in the US by Verizon and AT&T. Verizon is launching LTE in the 700 MHz spectrum and is among the first in the world to launch LTE, starting with 25 to 30 markets in 2010, covering approximately 100M people; and extending to cover its current 3G footprint in 2013. Additionally, there will be TD-LTE to be deployed by operators in fragmented TDD spectrum bands by Greenfield operators like Clearwire who have a lot of available 2.5 GHz spectrum available.

LTE ecosystem will be deployed in vast economies of scale from being a 3GPP technical specification that will be a combined LTE FDD & TDD standard. TD-LTE will ensure high-speed mobile broadband connectivity across a wide range of end-user devices and applications in networks with unpaired frequency bands. Another key benefit of TD-LTE is the 3GPP evolutionary approach from TD-SCDMA to LTE, which will increase the overall LTE ecosystem and scale by including a seamless integrated option for TD-SDMA operators such as China Mobile to migrate to TD-LTE.

TD-LTE devices must provide compatibility with legacy 3GPP systems, and a series of handover scenarios are specified to ensure conformance. These aim to ensure service continuity for the user, and check everything from idle mode and in-call intra-frequency TDD-TDD handovers, through inter-frequency changes and TDD-FDD handovers, handovers to 3G W-CDMA and HPSA systems, and finally to handing over from TDD to GSM.  3GPP has been successful in fulfilling its goal to achieve a single radio-access specification equally applicable to paired and unpaired spectrum. From a specification perspective, differences between FDD and TDD mode are on the physical layer and, particularly the frame structure. The differences found on higher layers are limited and are related to configurability of the physical layer and slightly different timing relations due to the discontinuous nature of uplink and downlink.

TDD and Interference

To avoid severe interference between uplink and downlink transmissions despite the fact that the two links use the same frequency, the cells in a TDD network typically use the same uplink downlink configuration together with inter-cell synchronization to a common time reference to align the switch-points among all the cells. This avoids interference between the two links as uplink and downlink transmissions do not occur at the same time. This is especially important in macro deployments with antennas placed above rooftops with possible line-of-sight-like propagation conditions between base station antennas. In this case base station-to-base station interference may otherwise severely degrade uplink reception of base stations.

Due to the propagation delay, a downlink transmission from a distant base station is still propagating at the base station trying to receive uplink transmissions even though all base stations switched from downlink to uplink at the same time. This causes interference at the base station at the beginning of the uplink period. Even though it is expected to be highly scenario dependent, it may be noted that for base stations with elevated antennas and little downtilt. This will require interference mitigation techniques like downtilts, adding filters at transmitters and receiver, use adaptive antennas, Implement transmitter power control and utilize antennas with low side lobes.

Generally TDD has worse coverage for a given data rate, due to the inherent discontinuous uplink transmission and the fact that both FDD and TDD terminal have the same uplink transmission. This is true for any TDD system; however, for LTE, the subframe structure for both FDD and TDD are the same and the users are scheduled on a subframe basis.

TD-LTE Spectrum

Around the world several spectrum bands have been allocated to support TD-LTE. Many countries throughout the world have TDD spectrum available and it is expected that these spectrums will trade at a much lower price per MHz/population than their FDD equivalents. Most likely 2.3GHz and 2.6GHz will be the most prominent TD spectrum bands used for TD-LTE.

Advantages of TDD over FDD:

Real-time adaptation provides highest transport efficiency

  • Millisecond real-time adaptation
  • 35% improvement over FDD/TDMA

TDD enables 100% use of available spectrum

  • Well-suited for wide, single block allocations and narrow, dual block allocations
  • Minimal latency variation enables prioritization of preferred subscribers and critical applications

Spectral Efficiency:

  • Minimize guard band
  • Change symmetry on the fly depending on subscriber’s needs
  • Adaptive downstream/upstream ratio allows for emerging new applications without the need for spectrum re-farming
  • Enables advanced technologies such as mesh network and adaptive antenna arrays
  • Highly effective for bursty data traffic while still supporting voice

In the U.S., the Broadband Radio Service (BRS) and the Educational Broadband Service (EBS) are in the 2496-2690 MHz band. While this band was previously known as Microwave Multipoint Distribution Service (MMDS), the band plan was recently rearranged and some additional rules changes were adopted.

While a network operator could gain enough spectrum to create a pairing and thus make the use of FDD a possibility, this approach has not happened yet. Even if an FDD approach was used, it would likely require equipment and devices with small economies of scale. Currently, most systems in the BRS and EBS bands have been based on TDD (e.g. UMTS TDD & WiMAX). As LTE becomes more prevalent in the marketplace and TD-LTE equipment becomes available, it will be an option for use in the BRS and EBS bands.

Future of TD-Ecosystem

Clearwire paved the way for LTE in US when they submitted a proposal to adopt the 2496MHz-to-2690MHz frequency band in the US for TD-LTE, and it was accepted by 3GPP meeting earlier this year. The acceptance is significant because it will enable Clearwire and other spectrum holders to deploy TD-LTE, which is the time division duplex (TDD) version of LTE, in the US. Clearwire was not alone in asking for the 2.6GHz spectrum to be defined as a TDD band for LTE. Indeed, there was broad industry support for the proposal from other companies, including: Sprint Nextel Corp. , NII Holdings Inc. , China Mobile Communications Corp. , UK Broadband Ltd. , Motorola Inc. Huawei Technologies Co. Ltd. , TD Tech Ltd. , WiChorus Inc. , ZTE Corp. , Chinese Academy of Telecommunications Technology , Nokia Siemens Networks , Cisco Systems Inc., Sequans Communications , Alcatel-Lucent , Alcatel Shanghai Bell Co. Ltd. , Rohde & Schwarz GmbH & Co. KG and not to forget – Qualcomm which has won a chunk of spectrum in India, where it plans to deploy TD-LTE.

** B3G is a terminology for Beyond 3G technologies and has been coined by Martin Sauter – http://mobilesociety.typepad.com/mobile_life/

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