Archive for July, 2010

QOS over 4G Networks

Cellular network operators across the world have seen an explosive growth of mobile broadband usage. Traffic volume per subscriber is increasing daily; in particular, with the introduction of flat-rate tariffs and more advanced mobile devices. Operators are moving from a single-service offering in the packet-switched domain to a multi-service offering by adding Value added services (VAS) that are also provided across the mobile broadband access. Examples of such services are multimedia telephony and mobile-TV. These services have different performance requirements, for example, in terms of required bit rates and packet delays. Solving these performance issues through over-provisioning typically is uneconomical due to the relatively high cost for transmission capacity in cellular access networks which includes radio spectrum and backhaul from the base stations. Read more…

Categories: LTE, WiMAX Tags: ,

SDR – A silent revolution

Software Defined Radio, as an essential feature for radio base-stations has been adopted by most RAN infrastructure vendors to manufacture their Base Station equipment. With the proliferation of multiple RAN access standards – 2G/3G/4G and various flavors of technologies GERAN, UTRAN, WIMAX and LTE the need for cost savings and efficiency for a base-station holds true in a fast evolving ecosystem.

They go by many marketing names – Single RAN, Uni-BTS, Multi-RAN and Multi-standard Radio. But they all mean essentially the same thing – relatively simple upgrades that allow a single standard base station to support multiple technologies. The next few years will see a rapidly growing – although possibly short-lived – wave of such upgrades throughout both mature and developing markets. A single RAN with multi-standard base stations help an operator move quickly and cost-effectively between technologies and they can be used to support multiple radio technologies simultaneously from a single cabinet.

The proliferation of Cognitive Radio into RAN architecture can be attributed to these three main factors:

Spectrum Re-farming

The biggest driver for SDR would be the spectrum re-farming efforts that will take place as the GSM technologies reach the twilight zone with the networks transitioning from GERAN to 3G/HSPA+ to LTE. Even though UMTS has offloaded most of the 2G networks, there are still pockets of the world where GSM/EDGE is still doing the bulk of the work by providing voice services and coverage. Refarming of 900 MHz GSM/UMTS is the best example of where multistandard base stations have been used.

Spectrum refarming has taken place in Europe and will also be considered by FCC in future as we strive to reach mobile broadband milestones. As B3G networks become more spectrally efficient with OFDMA offering more gains for spectrum bands of 10MHz and above. Refarming has its advantages as spectrum is scarce and allowed to recapture lower frequencies. All other things being equal, the lower the frequency, the further a radio signal propagates, which meant that UMTS900 offers a significant improvement over UMTS2100 for cell range and coverage. This translated into fewer sites and cost savings for network build and opex, as well as faster network roll-out. Some other benefits include potential improvements in indoor coverage and better voice quality compared with older technologies.

A GSM operator could now deploy UTRAN/LTE with a single BTS/BBU hardware swap with a scope to do an upgrade when LTE-Advanced along with IMS/MBMS is launched.

LTE – RAN Sharing and Het-Nets

The LTE architecture enables service providers to reduce the cost of owning and operating the network by allowing the service providers to have separate CN (MME, SGW, PDN GW) while the E-UTRAN (eNBs) is jointly shared by them. This is enabled by the S1-flex mechanism by enabling each eNB to be connected to multiple CN entities. When a UE attaches to the network, it is connected to the appropriate CN entities based on the identity of the service provider sent by the UE. This makes the UE to handover from LTE to non-3GPP access technologies.

RAN sharing as a concept has taken off with Orange and T-Mobile in the UK, as will become the path of choice for many operators as they migrate to 4G, due to various reasons. Operators in the past have paid high amounts for spectrum for 3G and 4G, and to realize their return on investment networks of the future will have to follow a network sharing model that suits their network needs. And an SDR based RAN upgrade would be profitable for migration path that can be easily upgraded in future.

SRVCC (Single Radio Voice Call Continuity) and CSFB (Circuit Switch Fallback) are mechanisms for initial LTE deployment that will pave the way for operators who deploy LTE networks before a single industry approach for Voice/VOIP solution is adapted for 3GPP-LTE. Two initiatives currently undergoing standardization are the VOLGA and One Voice, and till that plays out an SDR solution would very much  useful in deploying Het-nets (Heterogeneous Networks).

For Het-nets using CDMA and LTE technologies which use different frequency bands, such as 800MHz or 1900MHz for CDMA and 700MHz or 2.6GHz for LTE, there are no currently available mature RF modules that can simultaneously support two mutually remote frequency bands. However, the two networks can use the same baseband unit (BBU). This approach has two advantages: (1) A shared BBU reuses transmission equipment; (2) Different RF units and antenna feeder systems allow the CDMA and LTE networks to be independently optimized, especially the antenna and downtilt angles. This again is an example where SDR would be the most economical solution.

SDR – Mature Technology

SDR as a technology has matured and has come a long way in terms of deploy-ability on the field, with the RRU(Remote Radio Heads) and BBU(Baseband Units) being deployed heavily due to cost savings. Compact base-stations (BTSs) are the latest base station design to be introduced in the market and offer operators flexibility and cost savings while retaining the performance of macro BTSs as they can be installed in single-sector or multiple-sector configurations as alternatives to distributed BTSs with remote radio heads (RRHs). Compact BTSs do not require ground shelters and cooling equipment, and also support high-performance features such as multiple antennas per sector with multiple input, multiple outputs (MIMO) and beamforming.

Several operators are currently assessing the feasibility and cost savings that SDR can offer to them and are starting to include the new concepts in their networks. Vendors like ZTE, Motorola, NSN and Vanu have developed hardware with their Flexi-BTS platforms that have scaled across radio access technologies.

Network operators, including Vodafone Spain, Hong Kong CSL and others, are proving that SDR can increasingly save costs in the network and are acting as greenfield attempts for SDR. Although the majority of mobile operators are now deploying SDR for future upgradeability, Hong Kong CSL has consolidated hardware from several infrastructure vendors into a single platform and is now operating a much more cost effective and efficient network.


According to ABI Research mobile networks practice director Aditya Kaul, “The first increase in multi-standard upgrades will come from developing markets, especially India, that are now deploying 3G networks. Further momentum will come from LTE rollouts in mature markets.”

“One of the major drivers for this coming wave of upgrades is spectrum refarming,” Kaul continues. “Like many other ‘natural resources’, fresh spectrum is getting scarce. But there are significant amounts previously allocated that are now un- or under-utilized. Multistandard upgrades allow operators to put that spectrum to new uses. Upgrades for refarmed spectrum now account for just 10% of the total market, but their future is bright.”

SDR as a ubiquitous technology is here to stay and upgrades involve adding a baseband line card or doing a simple software update to existing baseband cards. For example such an approach would allow a WCDMA base station to move to HSDPA, HSPA+ and possibly LTE standards. Latest advances in RF and SDR technology allow RF components to be reused if operation is in the same frequency band. These upgrades will start to gather steam in 2011 and will continue accelerating for several years before the tempo eases again around 2014-2015.

To download a PDF click Here – SDR – A Slient Revolution

Categories: Broadband, LTE, WiMAX Tags:

Migration strategies for WiMAX 802.16e

Last few days have been an eye opener for NBA fans – the King left Cleveland!  And the owner of Cavs got upset, and wrote an open letter to LeBron – but has anybody given a thought what LeBron as person might be feeling – a need to fulfill his dream and willing to take a pay cut in the process? So, why am I taking about NBA and LeBron?  Well WiMAX is in a similar position, a great technology and ecosystem that is still in the process of discovering its potential, and achieving maturity. The way it has been deployed and the speeds it generates is 3G+, but there is a vast potential for it to achieve better which has remained untapped.

WiMAX Forum is working on the 802.16m specs but there are no takers for it, yet. Yota – a Russian WiMAX provider has stopped rollout of WiMAX, Indian spectrum auction is over but the tide seems to have turned the TD-LTE way. Clearwire has taken a timeout and said that they will evaluate their strategy and decide whether to go TD-LTE or WiMAX Rel.2. All this news sound like a death knoll for WiMAX technologists and evangelists, are they with the team that is losing out?  A defeated technology always takes a backseat, and will remain a niche. Will that be the way WiMAX will go? It might be the most probable way – so what happens to the operators who have deployed WiMAX 1.0, will they survive the race towards 4G supremacy? What will happen to the operators who have deployed WiMAX, will they have a migration strategy in place or cut their losses and migrate to 3GPP ecosystem?  Let us explore the possibilities and pros and cons for every move and a deeper understanding of the evolution of the ecosystem.

Two main contributors for any WiMAX operator on the evolutionary path to newer 4G wireless technologies would be availability of spectrum and broad device ecosystem support. Sufficient amounts of Time Division Duplexing (TDD) spectrum are not available for all operators in all applicable frequency bands to allow for simultaneous or multi-carrier migrations. This spectrum availability issue will restrict some operators from deploying 16m or TD-LTE. In turn, a lack of deployable spectrum will limit the device ecosystem that vendors will support. Service providers offering applications in niche frequencies will just have to cope with high device costs if they do intend to compete in the 4G market.  However, the most important element in the consideration of spectrum availability and ecosystem support will be the presence of interoperable 16e/LTE or 16m/LTE end-user access devices for the still unfolding 4G roadmaps.

WiMAX 2.0

WiMAX forum released a progress report earlier this year explaining the 802.16m, enhancements and technology concerns. In December 2006 the IEEE launched an effort to further evolve the IEEE 802.16 Wireless-MAN OFDMA specification. This amendment, known as 802.16m, is designed to meet or exceed the requirements of IMT-Advanced (the 4th generation of cellular systems). With a number of stringent requirements for backwards compatibility, the 802.16m amendment will provide the basis for WiMAX System Release 2 and provide existing WiMAX operators a graceful migration path to gain performance enhancements and add new services. As was the case for 802.16e-2005, 802.16m is designed to support frequencies in all licensed IMT bands below 6 GHz and include TDD and FDD duplexing schemes as well as half-duplex FDD (H-FDD) terminal operation to ensure applicability to the wide range of worldwide spectrum assignments. This release should be able to address these:

  • Increased Coverage and Spectral Efficiency
  • Increased Capacity for Data and VoIP
  • Lower Latency and QoS Enhancements
  • Interworking with other Wireless Networks
  • Power Conservation
  • Other Advanced Features and Supported Services

Spectral Efficiency

Improvement in the link budget over WiMAX System Release 1 of at least 3 dB with the same antenna configuration.  Alternatively the improved link budget can be translated to increased cell edge user throughput resulting in a two times improvement over WiMAX System Release 1. Several other enhancements included in IEEE 802.16m will improve spectral efficiency for data services. These enhancements include:

• Extended and improved MIMO modes with emphasis on multi-user MIMO (MU-MIMO) on both DL and UL to enable support for up to 8 data streams in the DL and up to 4 data streams in the UL.

• Improved open-loop power and closed-loop control

• Advanced interference mitigation techniques including fractional frequency reuse and inter-base station coordination

• More efficient use of pilot tones with new sub-channelization schemes and a cyclic prefix of 1/16 vs. 1/8 to reduce layer 1 overhead in both DL and UL

• Enhanced control channel design on both DL and UL with

  • Reduced overhead
  • Improved coverage through power boosting and optimized channel coding
  • HARQ protection for control messages

The net result of these enhancements will provide more than 2 times improvement in average channel spectral efficiency.

Data Capacity: The spectral efficiency enhancements described in above leads directly to increased channel data capacity and increased peak data rates.

Multi-Carrier Support: The IEEE 802.16m amendment also supports channel aggregation of contiguous or non-contiguous channels to provide an effective bandwidth up to 100 MHz The channels do not need to have the same bandwidth nor do they need to be in the same frequency band. This capability will enable operators with access to multiple channels or licenses to achieve significantly higher peak and average data rates than is achievable with individual channels. Aggregating several 20 MHz channels, for example, could support peak data rates exceeding 1 Gigabit/sec.

VoIP Capacity: With persistent and group scheduling, faster HARQ retransmissions, rate matching, optimized QoS support, and the other spectral efficiency enhancements described in the previous section, VoIP capacity is significantly increased with 802.16m.

Latency improvements with IEEE 802.16m are achieved with the use of a new sub-frame based 4 frame structure rather than a fixed 5 ms frame as used with WiMAX System Release 1. This enables faster air-link transmissions and retransmissions resulting in shorter user plane and control plane latencies. Latency objectives for IEEE 802.16m are:

  • Link Layer/User Plane: < 10 ms DL or UL
  • Hand-Off Interruption: < 30 ms
  • Control Plane, Idle to Active: < 100 ms

In addition, some of the 802.16m features already cited will enhance the end-user experience.

• The use of femto-cells can lead to higher average user throughput for users at the cell edge or indoors.

• 802.16m provides a shorter handoff interruption time to other Radio Access Technologies including – Wi-Fi Networks, 3GPP: HSPA, LTE, and LTE Advanced, 3GPP2: 1x-EVDO

• Idle Mode efficiencies like broadcast traffic without the need to register with a specific base station.

• Enhanced Multicast Broadcast Services (E-MBS) to provide greater broadcast and multicast spectral efficiency and support for switching between broadcast and unicast services.

• Enhanced GPS-based and Non-GPS-based Location Based Services (LBS) using triangulation schemes with < 30 seconds latency for location determination.

• Enhanced security with more advanced encryption schemes assuring confidentiality of user identity and user-generated data packets (e.g. location privacy and user identity protection).

• Mobility: An IEEE 802.16m mobile station will maintain a connection up to 350 km/hr and in some cases 500 km/hr depending on the operating frequency band.

• Self-Organizing Network (SON) features to enable self-configuration and self-optimization. Self-configuration enables true plug and play of network nodes and cells as well as fast reconfiguration and compensation in cases of failure. Self-optimization ensures optimal network performance with respect to service availability, QoS, network efficiency, and throughput under changing traffic and environmental conditions.

This migration path will be very seamless and the most logical path to ensure for operators that have 802.16e systems today.


LTE from its inception was designed to provide a single radio interface supporting both FDD and TDD to provide an even larger economy-of-scale benefit to both duplex schemes. Virtually all of the physical-layer processing is identical for FDD and TDD, enabling low-cost implementation of terminals supporting both the FDD and TDD modes of operation. According to Monica Paolini from Senza Fili consulting – “TD-LTE throws a wrench into this picture. LTE becomes much more intriguing–almost disruptive. “

And that in itself is the very basis for LTE ecosystem, it is almost as similar to the WiMAX standards, but has the advantage of already available WCDMA/UMTS customer base that will be migrated to LTE. Some of the advantages like the possibility for different uplink and downlink bandwidths, enabling asymmetric spectrum utilization.

Depending on regulatory aspects in different geographical areas, radio spectrum for mobile communication is available in different frequency bands of different sizes and comes as both paired and unpaired bands. Paired frequency bands imply that uplink and downlink transmissions are assigned separate frequency bands, whereas in the case of unpaired frequency bands, uplink and downlink must share the same frequency band. An essential part of any TDD system is the provisioning of sufficiently large guard periods during which equipment can switch between transmission and reception with no overlap of signals to be transmitted and received. In LTE, guard periods are created by splitting one or two subframes, referred to as special subframes, in each radio frame into three fields: a downlink part (DwPTS), a guard period (GP), and an uplink part (UpPTS).

A successful migration to TD-LTE for a WiMAX system would be possible only if they are backward compatible and an Inter-RAT handover. This is possible with the Mobile IP (MIP) based hard handover called Vertical Handover (VHO). The MIP mechanism hides the heterogeneities of lower‐layer technologies and provides a seamless handover between WIMAX-3GPP, though it has shortcomings like degradation of user experience and loss of buffered packets at the ASN and SGW.

Inter-Technology Handover

There are four general classes of Inter-RAT handovers, for service continuity between different technologies – 3GPP and non-3GPP including WiMAX, EVDO, etc.

Single Transmit Device with MIP (IETF RFC 3344)

This is simple MIP-based mobility using a device that is only capable of communicating in one technology at a time. Two examples of this approach are the single transmitter versions of the non-optimized inter-technology handover procedure defined in the 3GPP standards for inter-technology mobility between WiMAX and LTE and between EVDO and LTE. Since the device can only communicate with one technology, it must break its connection with the source network before it can establish a connection with the target. Depending on the technology, the signaling associated with getting access to and authenticating on the target network can be quite time consuming (on the order of several seconds) and cause a significant gap in the user’s session.

Dual-Transmit Devices with MIP

For environments where the level of inter-standards cooperation is less pronounced or where there is an urgent need to get inter-technology mobility deployed quickly, the Dual-Transmit Device (DTD) approach is attractive. In this approach the device does a true make-before-break handover to prevent data loss or the need for retransmission. The device uses its second transmitter to register and authenticate on the target network while maintaining its existing data session on the source network. Once the preliminary work is completed, and the device is ready to receive data on the new network, it uses a supported Internet protocol such as Mobile IP to move the data stream from the source to the destination network. The LTE standards accommodate the use of MIP in combination with DTDs to support efficient inter-technology mobility between LTE and WiFi. The WiMAX Forum is also standardizing the use of DTDs with MIP with the primary goal of supplying mobility between EVDO and WiMAX.

RAN Interconnect

This requires the source and target access networks to be intimately connected in some way so that they can exchange control messages to help guide the movement of the device from one access technology to the other and to reduce the time that device is unavailable on either network. Historically this approach has been available for different generations of the same root technologies such as cdma2000 à EVDO or GSM à UMTS, and this approach is being carried forward to provide mobility between LTE and GSM or UMTS. In all these cases the old and new technologies were controlled by the same standardization body, and the interworking can be just as easily viewed as a backwards compatibility requirement as an inter-technology mobility requirement. With the introduction of LTE however, the limitation of access network interconnection to technologies covered by the same standards body is changing. With the help of its member organizations, the LTE standards body, 3GPP, is working closely with the EVDO standards body, 3GPP2, to define inter-technology handover procedures that include mechanisms for interconnecting the LTE and EVDO RANs. Handover mechanisms that include exchange of information between the source and target RANs are generally referred to as optimized handover in the LTE standards. Optimized handover will support low-delay inter-technology handovers that can support demanding applications such as VoIP and video streaming. Currently LTE-EVDO optimized handover has made the most progress in the standards process, but optimized handover between LTE and WiMAX is also work by both WiMAX Forum and 3GPP.

Dual Transmit Device with SIP

Due to a variety of practical, technical and business factors, MIP can be difficult to implement in some environments leading to the fourth approach of DTDs coupled with the Session Initiation Protocol. SIP can often be used in conjunction with dual-transmit devices instead of MIP. Additionally, SIP is the only choice if there is a need to move data sessions between devices as well as between technologies – e.g. a requirement to move a video session from a plasma screen supported by a set-top box connected to a DSL link to an LTE mobile device. An obvious drawback to this approach is that it is only applicable for those applications based on SIP. Also it will not work for any application that is sensitive to a change in a correspondent’s IP address (e.g. many applications based on TCP). Some additional standardization effort is needed to support inter-device and inter-technology mobility with SIP and IMS. The complete sets of standards were completed in 3GPP Release 9.

Inter-technology mobility offers operators the promise of extracting more value from their access networks and provides them with a powerful set of tools for matching network resources to application requirements. Inter-technology mobility is a key facilitator for the incremental rollout of an LTE network.

The IEEE 802.21 body is attempting to model an access-network-independent abstraction of inter-technology handover that could be used with any pair of access network types. Concepts developed by IEEE 802.21 for solving general inter-technology mobility problems (MIH – Media Independent Handovers), are being carried over into other standards bodies where they are adapted to resolve problems specific technologies. Also the Internet standards body, IETF, has been working closely with the wireless standards community to ensure that new internet protocols are well suited for wireless inter-technology applications (e.g. Proxy Mobile IP version 6 – PMIPv6 – and DIAMETER).


Whatever the outcome of the migration path choices for WiMAX operators, it shall be important for their survival as first mover advantage in the 4G market.  As Mobile WiMAX operators plan their deployments, many anticipate making a full or partial migration to next-generation technology. In fact, it is not a question of whether to migrate, but rather of how to migrate. The ecosystem shall be defined by the standards – WiMAX Forum is slated to finalize the 2.0 standards by Q4 2010 and TD-LTE trials are still ongoing with production networks slated to roll out by 2012. So the question that needs answered is can they upgrade to 16m now but preserve an upgrade path to TD-LTE? Or is it better to maintain the network with 16e or 16e-Enhanced? I would think that available spectrum, developing ecosystem and operator partnerships would play a vital role in the decision making. RAN-sharing too should be taken into consideration as spectrum assets become scarce for operators as well as the fact that many operators have overpaid for the spectrum assets and a spectrum re-farming efforts gain momentum.

For a PDF copy click here

Categories: Broadband, LTE, WiMAX Tags:

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.


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.

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

5 Reasons why WiMAX will always be a Niche Technology

WiMAX on the very onset had a great time to market advantage for brining in an All-IP network along with TDD advantages that started the race for 4G supremacy. But somewhere along the line 3GPP caught up with the onset of LTE specs development and has commitments from more than 88 operators across the world and an ecosystem was born. The other day while watching TV, I had an analogy – Larry King had just announced his retirement from CNN and he was speaking with Bill Maher, and when asked of his successor, he mused maybe Ryan Seacrest. That is when it struck me WiMAX is like Bill Maher – a great guy but his place is on HBO not mainstream CNN, and Ryan Seacrest is like LTE, effervescent and very mainstream.

This reminds me of the other wireless battles in the past the CDMA vs. GSM, which complemented each other and help make the user experience better. The battle is never about which technology is better, as both have their own advantages and disadvantages, but about the adaptation by the suppliers and the media. Most technologies adaptations are based on various factors like spectrum policy, economic considerations, supplier ecosystem, media and target market segment.

Here are five factors that have had an impact on the WiMAX ecosystem.

Economic Downturn impact:

The impact of the market crash in 2009 has had far reaching implications to all industries especially the discretionary spending budgets of the Telco’s to upgrade their networks. Many of the far reaching network augments and technology upgrades for traditional Telco’s as well as wireless providers were dictated by the economic factors. 2009 was a disastrous a year as it seemed at the outset, starting as it did with the catastrophe and bailouts for the financial industry, real estate, and the auto industry. And this not surprisingly has impacted the growth of WiMAX putting pressure on Greenfield operators. Several suppliers reported that a bottom had been reached and expected an upturn in business – modest or otherwise – going forward.

One of the biggest trend that developed over the last couple of years was the level of consolidation at the infrastructure layer; with several large RAN players either having exited the space or merged with other players over the last year. Nortel was divvied up and assets scooped up by other infrastructure vendors, Navini became Cisco to be shut down completely later, Starent was also bought over by Cisco, Wichorus was taken over by Tellabs, etc. One of the strong transformations under way in the telecom sector is the way large telecom equipment players are becoming Managed Services players (such as Ericsson, ALU and NSN); with an increasing part of their revenues coming from services business versus hardware / equipment sales.

Industry Trends:

  • Corporate moves to control spending did not stall shifts to greater use of communications.
  • Flat and pre-pay plans gained increased market share during 2009. While this put downward pressure on ARPUs and margins, the industry was bolstered by the complimentary rise in 3G/HSPA+ broadband.
  • Government initiatives for broadband infrastructure and service development have gone forward in the US, China and Brazil.
  • Operators stressed applications and a unified web-enabled experience more than ever before. The usage model has experienced a dramatic shift, which is evident in the rising market shares of Apple iPhone, Samsung, RIM and other web-device competitors. Google Android has made significant inroads.
  • Underserved markets including Russia, Malaysia, and the African continent saw robust growth. A few markets such as India continued to see delays in spectrum auctions and deployments due to economic outlook.
  • As expected, several operators have nudged out their earlier forecasts for commercial availability of LTE service into late 2010 or early 2011. Some operators announced they would upgrade to HSPA and HSPA+.

LTE and its variant of TD-LTE:

There are two versions of LTE. FDD-LTE uses the FDD paired spectrum with two separated channels, one for the uplink and one for the downlink, which is the type of spectrum most mobile operators have. TD-LTE uses TDD unpaired spectrum channels that combine uplink and downlink, and split resources on the basis of real-time demand. Voice is inherently symmetric in the uplink and downlink so it is well suited for FDD spectrum allocations. Data traffic benefits from TDD spectrum, as it is typically asymmetric but the degree of uplink/downlink asymmetry is not fixed. The development of TD-LTE was initially pushed by China Mobile and regarded as a mainly Chinese standard, similarly to TD-SCDMA.

The appeal of TD-LTE has widened well beyond China. The recent announcement of Qualcomm to bid for TDD spectrum in India to support a TD-LTE deployment confirms–although it was not required to validate–the emergence of TD-LTE as global technology, likely to command a substantial market share.

The FDD LTE and TD-LTE versions of the 3GPP standard are very similar. As a result, devices can support both the FDD and TDD interfaces through a single chipset–i.e., without any additional cost. This is a hugely important new development: TD-LTE will benefit from the wide availability of FDD LTE devices that will be able to support TD-LTE as well. Unlike WiMAX, TD-LTE does not need to prove to have a substantial market share to convince vendors to develop devices. Vendors do not need to develop new devices, they simply need to add TD-LTE support to the existing ones.

There is a lot of TDD spectrum available, and in most cases it is cheaper and under-utilized. 3G licenses frequently have TDD allocations and upcoming 2.5 GHz auction in most cases contemplate TDD bands.

The increasing availability of base stations that can be cost-effectively upgraded will make it possible and relatively inexpensive for WiMAX operators to transition to TD‑LTE using the same spectrum allocation. The transition will still require substantial efforts and be justified only in some cases, but it will make it easier for WiMAX operators to have roaming deals and to have access to the same devices that LTE operators have.

WiMAX operators will also be barely affected by TD-LTE in the short term. WiMAX is years ahead in terms of technological maturity, devices and ecosystem. This gives them a strong advantage in comparison to TD-LTE operators: They know the technology already, they have a network, and they have customers. They also have the choice whether to switch to TD-LTE or not–and, more importantly, they have no pressure to do so before TD-LTE has reached the maturity they feel comfortable with or until the WiMAX 16m prospects become clearer. WiMAX is losing the battle, but winning the war. WiMAX operators are increasingly keen on requiring vendors to be able to support both a transition to WiMAX 16m and to TD-LTE as smooth as possible.

That is the rule of evolution – big fish eat small fish!


LTE development has been driven by operators; this type of initiative is one of the key differences between LTE and its predecessors, which were primarily vendor-driven technologies. Several operators (Sprint Nextel, China Mobile, Vodafone, Orange, T-Mobile International, KPN Mobile, and NTT DoCoMo) formed a limited liability company called Next Generation Mobile Networks (NGMN) Ltd in September 2006. Subsequently, NGMN defined the high-level requirements for all next-generation broadband wireless networks – not just LTE.  3GPP works very closely with NGMN to define the scope of work and the charter for LTE and LTE-Advanced.

In addition, the LTE/SAE (Service Architecture Evolution) Trial Initiative (LSTI) was formed through the cooperation of vendors and operators to begin testing LTE early in the development process. NGMN defines the requirements and LSTI conducts testing to ensure conformance. The 2008 Mobile World Congress was seen as a turning point for LTE. This conference showcased the increased momentum in LTE development and support from both the device and infrastructure perspective. Vendors showcased advanced LTE devices and infrastructure while operators announced their LTE strategies or trial plans.

WiMAX is an offshoot of IEEE wireless standards including 802.11, 802.16, 802.20, and 802.22 starting out with the view that the complex task of designing wireless networks must be chunked down into discrete task groups and purpose designed standards. These tasks are given mandates to fulfill specific functions and then work to collaborate across lines of development. This has been necessary because IEEE is open to all, and thus must build a consensus among many participants from around the globe who may have different orientations. However, this approach led to islands of development and commercial momentum that are less organized and strategic than the well-situated UMTS/LTE industry approach. The WiMAX effort has been embryonic – although developing a competitive supply ecosystem, WiMAX has not yet had the scale to play the role of market assimilator similar to UMTS.

The WiMAX Forum might have jumped forward in their thinking to the situation the industry faces today: it still faces the catch-22 of building commercial momentum while needing huge amounts of capital to acquire spectrum and fund large-scale deployments to compete with the mobile industry. Proponents of 3GPP LTE point to the large volumes their industry will develop that are expected to lead to lower cost per unit and operation efficiencies.

Backward compatibility with 3GPP and Roaming:

The first challenge for WiMAX roaming is interoperability. WiMAX is deployed in specific markets and is concentrated in urban areas in the US. In order for users to access WiMAX services outside of their operator’s WiMAX network coverage area, devices must be interoperable across other WiMAX networks and between various vendors’ equipment.  But the ecosystem is yet to be delivered, as Sprint just came out with the HTC EVO last month.

The second challenge for WiMAX roaming is that of multiple WiMAX air interface profiles. Operators do not necessarily have the same frequency bands available within their respective geographic regions. Depending on the country, carriers may use different radio bands for their WiMAX networks, such as 2.5 GHz or 3.5 GHz, and client devices may be equipped to use only one of these. The WiMAX industry is in need of devices that support multiple bands. This was a challenge for previous generations of technologies as well, and was addressed by the availability of dual band, tri band and quad band devices. The same is expected to happen within the WiMAX space to address frequency challenges.

Meanwhile LTE doesn’t face a situation like this as the critical factor in 4G success will spill over from 3.5G – having the hottest hand-held devices. Suppliers will dance to the tune of the largest operators with the most significant coverage.


HSPA+ is aimed at extending operators’ investment in 3G/HSPA networks and easing migration to LTE. HSPA+ with 2×2 MIMO, 64 Quadrature Amplitude Modulation (QAM) in the downlink, and 16 QAM in the uplink will increase data rates up to 42 MB in the downlink and 11.5 MB in the uplink. In addition, the one-tunnel architecture flattens the network by enabling a direct transport path for user data between the Radio Network Controller (RNC) and the GGSN. Control data will still use the SGSN. There is also an option to integrate the RNC directly into the eNodeB, thereby eliminating the need for separate hardware. These additional capabilities address the need for augmented bandwidth, reduced latency, and network elements with the same 5 MHz channel bandwidth used in UMTS networks. Consequently, operators can leverage existing 3G spectrum to deploy HSPA+. In addition, this architecture supports enhanced VoIP services. As a result of these enhancements, the need to upgrade to LTE is not as compelling. Operators feel that 42 MB will meet their data requirements for the next several years. The only drawback is that HSPA+ is still a CDMA-based technology and will lack the increased efficiency of OFDM (orthogonal frequency-division multiplexing).

Here is a HSPA+ Vs WiMAX study by Rich Brome from

A test was run on the T-Mobile HSPA+ network and the Sprint 4G (Clearwire) network, across six locations in Philadelphia, and an average user experience was calculated.

  • Both were considerably faster than CDMA EVDO Rev. A
  • HSPA 7.2 devices deliver surprisingly fast data on T-Mobile’s upgraded network
  • T-Mobile’s HSPA+ is more than twice as fast as WiMAX
  • Latency test –  T-Mobile’s HSPA+ was, better with a difference was one-tenth of a second
  • Sprint about their WiMAX network is that parts of their Philadelphia network are already at capacity, meaning the network is “full” with existing users and, essentially, maxed out.

Just as Sprint is still building its WiMAX network city-by-city, T-Mobile is still in the process of upgrading its network to HSPA+, also city-by-city. Once a city has been upgraded, T-Mobile’s HSPA+ coverage is the same as their existing 3G network coverage, since it’s the same network, just upgraded. T-Mobile’s upgraded HSPA+ network is worth a hard look.

** This comparison has its drawbacks, as Sprint network is loaded with 4G devices, whereas T-Mobile doesn’t have any HSPA+ capable phones. Also Sprint uses the Clearwire network as a direct tunnel, which impacts the latency of the network.


WiMAX is truly at a turning point today. It’s time to market advantage is being offset by the incredible dynamism of the LTE community and the scale that it has achieved in record time. Cost advantage is the last piece holding the machine together. Although wireless is a market rich in niches, the possible survival of a defeated standard could be very much defined by its cost. After the successive salves of operators’ announcements about their selection of LTE, the question of the survival of WiMAX is completely relevant. Many in the industry are now thinking that WiMAX may eventually disappear altogether, or else remain restricted to a small niche.

With the significant momentum that LTE is gaining, the battle could be well over if WiMAX can’t retain the cost advantage despite its lack of scale. WiMAX market dynamics could help overpass the scale limitation and help bail the standard out. WiMAX’s ability to compete in terms of cost may define its future and eventually ensure that WiMAX could still be an option for service operators in some emerging markets, for vertical applications and other niches.

You can now download this analysis here – 5_Reasons_WiMAX_be_a_Niche_Technology

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

Why I think that the Broadband stimulus is better than TARP?

I might be biased as somebody involved in the NTIA Broadband stimulus program, but then how many common folks like you and me have seen any of the TARP funds? I am not here to criticize the TARP program, as I think I have neither the expertise nor the reason to comment on its success. Maybe it avoided a complete crash of our economy or we just dodged the bullet temporarily, as Professor Roubini would like us to believe.  Broadband stimulus on the other hand will set people to work, digging trenches for running fiber as a result of middle mile projects or building networks as a result of last mile projects. It will benefit the rural America like never before, it will make access to broadband a fundamental right.

Are we closer to Finland yet ? Well Finland as we know has made become the first country in the world to make Internet access a fundamental right. As of this week, all ISPs in the country are required to ensure that each citizen has access to at least a 1Mbps speed connection. Read more…

Categories: Broadband, FCC

NTIA approves $795 Million for Broadband Stimulus

U.S. President Barack Obama’s administration will announce nearly $795 million in grants and loans for broadband deployment projects across the nation on Friday, officials with two federal agencies said.

The U.S. National Telecommunications and Information Administration (NTIA) and the U.S. Rural Utilities Service (RUS) will officially announce awards for 66 new broadband projects that will touch all 50 states, Obama administration officials said. The money, from the American Recovery and Reinvestment Act passed by the U.S. Congress in early 2009, is expected to create or save about 5,000 jobs, officials said.

The new awards will enable farmers to better track crop prices, enable rural health-centers to offer telemedicine services, and allow schools to provide distance learning services, added Tom Vilsack, secretary of the U.S. Department of Agriculture, the parent agency of the RUS. “It will also allow us to keep the United States at the center of innovation, and keep the companies that are located in rural America competitive, creating more opportunity and new jobs,” he said.

In the Recovery Act, Congress allocated $7.2 billion to the NTIA and RUS for broadband grants and loans. The NTIA will award $404 million to 29 projects Friday, and the grants will finance 6,000 miles of new fiber-optic lines, Locke said. Most of the money will finance middle-mile broadband network projects.

The NTIA has previously awarded $1.6 billion in broadband grants.

The RUS will award $390.9 million on Friday, with $163 million in loans and the rest in grants. The RUS has previously awarded $1.4 billion in Recovery Act funds to broadband projects. Most of the RUS money is focused on last-mile broadband projects.

Private investment of more than $200 million will help fund the projects announced Friday, the officials said.

Categories: Broadband Tags: