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Wednesday, September 29, 2010
RF Pattern Matching adopted in 3GPP Release-10
“The decision to incorporate RF Pattern Matching into the 3G UMTS specifications is needed for all service providers wanting to provide the highest-SLA option for LBS as it gives them more credible options for public safety and commercial applications,” said Manlio Allegra, president and chief executive officer at Polaris Wireless. “This level of LBS accuracy will create an improved user experience for wireless customers, which ultimately generates additional revenue streams for carriers and other enterprises offering LBS applications.”
Polaris WLS™ is a patent-protected implementation of RF Pattern Matching, which provides the best network-based location performance in urban and indoor settings and is a perfect complement to A-GPS, enabling a best-in-class hybrid solution. Polaris’ WLS™ works without the RF Pattern Matching definition in standards, but standardization through 3GPP allows for future performance enhancements and provides flexibility for the solution and carrier implementations. Polaris’s current WLS products will continue to operate within existing standards.
By being included in the 3G UMTS standard, Polaris’ location technology has received further validation as one of the most accurate in the world. Polaris will now be considered a preferred provider to Tier 1 carriers and infrastructure vendors who want to add a high accuracy location solution to their technology mix that meets the new 3GPP standard.
The FCC is currently considering new E911 Phase II regulations that would improve indoor location capabilities for first responders. Using RF Pattern Matching, Polaris’ WLS™ software solution enables carriers and OEMs to be prepared to meet these new FCC requirements with little or no investment in new infrastructure or hardware.
RF Pattern Matching Discussion document presented in 3GPP is embedded below:
Tuesday, September 28, 2010
SIMFi = SIM with WiFi

With SIMFi, you can convert a phone into a WiFi hotspot. The phone would use HSPA/LTE for data connectivity and at the same time it would broadcast WiFi signals for any equipment to connect to these signals and browse the web. Power consumption information have not been mentioned which I am sure would be a problem for the phone.
SIMFi Removes the need for additional accessories to facilitate transmission services (e.g. MiFi, USB modem, PCMCIA…) and can make connectivity a lot simpler, straigtforward and cheaper.

- SIM card compatible with the latest telecom specifications.
- SIM card: ISO 2FF plug-in
- The mobile phone does not need any special features.
- Modem WiFi integrated in the SIM card, works with 802.11b.
- The modem is guided by the SIM card's tools.
- Energy-saving features (works with 2G and 3G).
- The aerial is adaptable, allowing short- and long-range operations (from 2 cm to 30 m) managed by the SIM card's tools.
Monday, September 13, 2010
Femtocell Interference Management in real life
A major technical challenge that femtocell designers initially faced was the need to manage potential interference. It takes up to two years to install conventional base stations, during which time radio engineers meticulously plan a station’s position and radio characteristics to avoid interference. However, such an approach is not viable in the case of femtocells, deployed potentially in their millions at random. Automating a process conducted by radio engineers was no mean feat and simply would not have been possible a few years ago.
Fortunately, the fact that the walls of buildings keep 3G signals out and keep the femtocell’s signals in provides strong inherent interference mitigation for indoor femtocells. Extensive studies have shown that proper implementation of a few key techniques to reduce interference can take advantage of this attenuation in an intelligent manner. Such techniques include frequent monitoring of the cell’s surrounding radio environment combined with adaptive power control. Indoor users gain faster data rates, as do outdoor users who now operate on less congested cells, while it costs less for operators to deliver higher overall network capacity. Large-scale, real-world deployments are demonstrating that these techniques work in practice and even allow new approaches, such as operating 3G networks in the same spectrum as 2G networks.
AT&T has deployed femtocells on the same frequencies as both the hopping channels for GSM macrocells and with UMTS macrocells. They have tested thousands of femtocells, and found that the mitigation techniques implemented successfully minimise and avoid interference. The more femtocells are deployed, the more uplink interference is reduced.
It is very interesting to see that the interference is not causing any problems in real life.

Back in Feb, Femto Forum released a new report on "Interference Management in UMTS Femtocells". A similar report was released in Dec. 08. Then in March they released a similar report for OFDMA (covering both LTE and WiMAX) femtocells. They are interesting reading for those who are interested in this area.

- Advanced interference-aware cooperative PHY techniques,
- Improvement of the control plane procedures for seamless connectivity, and
- System-level evaluation and hardware demonstrator of the proposed femto-based network architecture.
More info on their website (http://www.ict-freedom.eu/). You can see their scenario document that shows different interference scenarios and also compares different approaches including those of Femto Forum, 3GPP and WiMAX.
Thursday, August 12, 2010
Whitepaper: Traffic Management Techniques for Mobile Broadband Networks
The report, Traffic Management Techniques for Mobile Broadband Networks: Living in an Orthogonal World,focuses on 3GPP networks and concerns itself specifically with traffic management, including the handling of traffic flows on 3GPP networks in contrast with other network management techniques that operators may deploy (such as offloading, compression, network optimization and other important mechanisms).
Mobile broadband networks are confronted by a number of challenges. In particular, the physical layer in mobile networks is subject to a unique confluence of unpredictable and unrelated, or “orthogonal,” influences. Moreover, mobile broadband networks have some important differences from their fixed brothers and sisters, which lead to different traffic management requirements. Among the most significant differences for purposes of traffic management is the need for more granular visibility to circumstances on the ground. Optimally, traffic management for mobile broadband networks requires visibility to what is occurring (by device or application) at the cell site level and in a timeframe that enables as far as feasible near-time reactions to resolve issues.
With the consumer in mind, an End-to-End (E2E) view of mobile service is critical for traffic management. For example, a consumer using a mobile phone to look up movie listings and purchase tickets considers the E2E service as the ability to see what movie is playing and execute a transaction to purchase tickets. 3GPP has endeavored to standardize increasingly more robust traffic management (Quality of Service, or QoS) techniques for mobile broadband networks with a consumer’s E2E view of QoS. It must be considered, however, that mobile operators typically do not have full control over E2E provisioning of services that depend on mobile broadband Internet access.
Global standards organizations like 3GPP play an important role in the development of traffic management through provisions for addressing QoS, particularly regarding interworking with non-3GPP access mechanisms. These are important new innovations, and the 3G Americas white paper notes that the efforts of standards development organizations should be intensified.
In addition, the configuration of end-user devices and content and applications not provisioned by the network operator not only impacts the experience of the particular user, but potentially other users in a particular cell as well. Efforts to drive further QoS innovations should be mindful of potentially adverse impacts from these sources and support and foster interoperability of third party applications with existing network platforms.
More innovations are needed throughout the mobile broadband ecosystem, in particular by application developers, in order to realize E2E quality of service. Furthermore, transparency in network management practices is important in fostering innovation, but requires a careful balancing to ensure consumer comprehension while safeguarding network reliability. Organizations with technical expertise such as 3G Americas are prepared to help to illuminate and progress the development of these new technologies.
“3G Americas stands ready to assist interested parties in the ongoing development and understanding of traffic management techniques,” said Chris Pearson, President of 3G Americas. “We are mindful that in this hemisphere and elsewhere, the industry has accepted an increasingly active role in addressing questions about service levels and innovation on mobile broadband networks.”
The white paper, Traffic Management Techniques for Mobile Broadband Networks: Living in an Orthogonal World, was written collaboratively by members of 3G Americas and is available for free download on the 3G Americas website at www.3gamericas.org.
Thursday, May 27, 2010
UMTS/HSPA State Transition Problems to be solved with LTE
The problem in UMTS/HSPA is that these state transitions take quite some time (in mobile terms) and can slow down the browsing experience. Martin has blogged about the state transition problems because of the keep alive messages used by the Apps. These small data transfers dont let the UE go in the IDLE state. If they do then whole raft of signalling has to occur again for the UE to go to CELL_FACH or CELL_DCH. In another post Martin also pointed out the sluggishness caused by the UE in CELL_FACH state.

Mike Thelander of the Signals Research Group presented similar story in the recently concluded LTE World Summit. It can be seen from the figure above that moving from IDLE to CELL_DCH is 1-3secs whereas FACH to DCH is 500ms.

Monday, May 24, 2010
Wednesday, May 12, 2010
Monday, April 12, 2010
HSPA finds success with Mobile Broadband Growth

- According to a report from AdMob, smartphonedata traffic grew 193% year-over-year in the month of February 2010. Smartphonesaccounted for 48% of its traffic in February 2010, up from 35% the year before. AdMobattributed this primarily to iPhoneand Android traffic.
- Deutsche Telekom CEO René Obermann is expected to double revenues by 2015 with €10 billion coming from mobile data traffic. Obermann said it would double the number of 3G smartphonesin the network to around 8 million by the end of 2010
- A recent report by In-Stat, stated that mobile broadband is now the second-largest access technology behind DSL, making up 18% subscribers
- Telia Sonera reported that the strong demand for mobile devices, including mobile broadband and Apple iPhone™, continued. Mobile data traffic in Nordic and Baltic operations increased close to 200% while the number of mobile broadband subscriptions rose by more than 60% during 2009.
- AT&T reported that Text messaging grew 50% YoY and picture messaging grew 130%
- According to IDC's Worldwide Quarterly Mobile Phone Tracker, vendors shipped a total of 54.5 million units Q4 09, up 39.0% from Q4 08. Vendors shipped a total of 174.2m units in 2009, up 15.1% from the 151.4m units in 2008. Converged mobile devices accounted for 15.4% of all mobile phones shipped in 2009, up slightly from 12.7% in 2008
- The number of people subscribing to broadband internet services in Australia grew rapidly with wireless broadband and 3G mobile services continuing strong growth in 2009, according to a new report by ACMA (Australian Communications and Media Authority). 3G now accounts for more than 50% of all mobile subscriptions, an annual increase of 44%. Internet subscriptions reached 8.4 million in June 2009, compared to 7.2 million in June 2008. Broadband subscriptions increased from 5.66 million to 6.72 million in the same period, with wireless subscribers gaining 162% to 2.1 million
- Vodafone's Data traffic has risen 300% in the past two years. Data now represents 11% of all European service revenues. Smartphones represent 20% of handsets sales. Around 40% of the company's European 3G/HSPA networks now support 7.2 Mbps. In the coming 6 months, Vodafone plans to upgrade 20-25,000 sites across Europe to HSPA+
- UK consultancy firm, Coda Research Consultancy, has predicted that mobile data consumption in the US is set to reach 327,000 terabytes a month by 2015, indicating a 40-fold rise in mobile data consumption over 5 years
- Mobile data traffic from PC modems and routers is forecast to increase 4-fold between 2010 and 2014, according to a report by ABI Research. 2,000 petabytes of data will be sent and received in 2010, a figure that will rise to about 8,000 petabytesin 2014
- Semiannual US wireless industry survey was released at CTIA in March 2010 revealing that wireless service revenues totaled $77 billion for the last half of the year. The real growth is coming from wireless data services -mobile Web, text messages, and other non-voice services. In the latter half of last year, revenue for wireless data service totaled > $22 billion, nearly a third of overall wireless services revenue and up 26% YoY. Steve Largent, President and CEO of CTIA, said in a statement. "Mobile broadband will increasingly play a vital role in people’s lives."
- A new study by Juniper Research has forecast that more than 1 in 10 mobile subs will either have a ticket delivered to their mobile phone or buy a ticket with their phone by 2014, representing a five-fold growth over the next five years.
- Strategy Analytics recently forecast that the number of active mobile broadband subscriptions worldwide is expected to rise to around 1.3 billion by 2014
- ABI Research announced that shipments of mobile broadband-enabled consumer products, which includes e-book readers, mobile digital cameras, camcorders, personal media players, personal navigation devices and mobile gaming devices will increase 55-fold between 2008 and 2014 with total shipments reaching 58 million units per year in 2014
Wednesday, March 10, 2010
HSPA+ to reach 168Mbps in Release-10

Sunday, February 7, 2010
3G Americas Publishes New Report on Technology choices for Mobile Broadband


Sunday, January 10, 2010
Technologies and Standards for TD-SCDMA Evolutions to IMT-Advanced

Thursday, December 3, 2009
MBMS and AMR-WB

Nokia publicly underlined its commitment to broadcast-mobile-TV standard DVB-H with the recent unveiling of the mobile TV edition of the Nokia 5330 and its pretax, presubsidy price tag of €155 (US$230), after some in the industry had questioned its enthusiasm for launching new DVB-H devices. Nokia also quelled any suggestions that it might start supporting the MBMS standard with its future device launches.
The price is a massive drop from the €550 price tag carried by Nokia’s last fully DVB-H-compatible handset, the N96, which launched in 3Q08. So the official line from Nokia is this: “All is well on the good ship DVB-H.”
Read more here.
Meanwhile, In China, China Unicom has launched 3G telecom services in 268 cities across the country, said Li Gang, another deputy general manger for Unicom Group, noting that the WCDMA network supports a 14Mbps download data transmission speed and a 7.2Mbps upload data transmission speed.
Notably, the carrier has adopted the most advanced R6 technology in its core WCDMA network to smooth a WCDMA-to-EPS migration in the future, according to Mr. Zhang.
The China Unicom network is expected to support MBMS and HSPA+64QAM technology in the first phase of a further evolution, shore up a HSPA+MIMO technology in the Phase II evolution, and prompt a LTE technology in the Phase III evolution, said Mr. Zhang, adding that the network will present a 100Mbps download speed and a 50Mbps upload speed after the Phase III evolution.
Read more here.

This is the second step in Orange’s HD voice strategy, following on from the launch of a high-definition voice service for VoIP calls in 2006. Over 500,000 Livephone devices have already been sold in France and the range will be extended to other Orange countries over the coming months.
The first mobile handset integrating high-definition voice capability that will be launched by Orange Moldova is the Nokia 6720c. This innovative handset integrates the new WB-AMR technology, which is widely expected within the industry to become a new standard for mobile voice communications.
Thanks to the Adaptive Multi Rate-WideBand (AMR-WB) codec, double the frequency spectrum will be given over to voice telephony over traditional voice calling. Orange boasts that the result is "near hi-fi quality" and "FM-radio quality", which seems an odd comparison.
Saturday, November 21, 2009
Updates from GSMA Asia Mobile Congress 09 - Day 2

- 55% of Japan has migrated past 3G to 3.5G
- Japanese mobile content industry is worth 14 Billion dollars annually
- 50% of mobile data in Japan is consumed in the home, the peak time for mobile data consumption is between 9 PM and 10 PM; and smartphone users consume 10 times more data than non-smartphone users.
- Japan's Softbank will turn off their 2G network already in March of next year, 2010.
- Allen Lew, Singtel's CEO, said that in Singapore almost 50% of smartphone owners are shifting web surfing activity away from PCs.
- Jon Fredrik Baksaas, Telenor's President and CEO, spoke about the eco-friendly initiatives they have, such as solar powered cellular network base stations etc, but an interesting tidbit that came out, is that in Europe, Telenor has installed 870,000 household electricity meters that are remote digital meters and operate on the GSM cellular network, in Sweden. As Sweden's population is only about 7 million people that is probably a third of all households.
- Rajat Mukarji of Idea (one of India's largest mobile operators), told us of the Indian market, where the average price of a voice minute is 1 cent (US). He Mr Mukarji also said that in India mobile is the first screen, not the fourth screen; and mobile is the first internet connectivity opportunity for most people of India.
- Tony Warren, GM of Regulatory Affairs at Telstra, told that 60% of phones in Australia are 3G already, and over half of mobile data is now non-SMS type of more advanced mobile data. And he said that MMS is experiencing enormous growth, grew 300% in the past year.
Sunday, September 20, 2009
HSPA Functions and Benefits

Thursday, September 17, 2009
Wireless Subscribers Forecast 2014

Source: Informa Telecoms & Media, WCIS+, June 2009
Thursday, September 10, 2009
New report on Mobile Broadband Evolution from HSPA to LTE-Advanced

The white paper, HSPA to LTE-Advanced: 3GPP Broadband Evolution to IMT-Advanced (4G), discusses the 3GPP evolution of EDGE, HSPA and LTE, their capabilities and their positions relative to other primary competing technologies and how these technologies fit into the ITU roadmap that leads to IMT-Advanced.
The following are some of the important observations and conclusions of the report:
- HSPA Evolution (HSPA+) provides a strategic performance roadmap advantage for GSM-HSPA operators. Features such as dual-carrier operation, MIMO and higher-order modulation offer operators multiple options for improving their networks, and some of these features are simply network software upgrades.
- Persistent innovation in developing HSPA and HSPA+ is bringing UMTS to its full potential providing mobile broadband to the mass market; in current deployments, HSPA users regularly experience throughput rates well in excess of 1 Mbps under favorable conditions, on both downlinks and uplinks, with 4 Mbps downlink speed commonly being measured. Planned enhancements such as dual-carrier operation will double peak user-achievable throughput rates.
- LTE has become the next-generation platform of choice for GSM-HSPA and CDMA/EV-DO operators.
- The 3GPP OFDMA approach used in LTE matches or exceeds the capabilities of any other OFDMA system providing the most powerful wide area wireless technology ever developed. Peak theoretical downlink rates are 326 Mbps in a 20 MHz channel bandwidth.
- 3GPP has made significant progress investigating how to enhance LTE to meet the requirements of IMT-Advanced in a project called LTE-Advanced.
With a customer base of 4 billion connections today, the GSM family of technologies is available on nearly 800 networks in 219 countries worldwide. Building on this base, UMTS-HSPA – the world’s dominant mobile broadband technology today – has proven to be the most widely deployed and adopted 3G technology of all time, with more than 352 operators in various stages of deployment, including 277 commercial HSPA networks in 116 countries.
The white paper explains the tremendous opportunity afforded to GSM-HSPA operators via the 3GPP roadmap to HSPA+. While OFDMA systems such as LTE and WiMAX have attracted a great amount of attention, evolving HSPA to exploit available radio technologies can significantly enhance its performance capabilities and extend the life of sizable operator HSPA infrastructure investments. Techniques include advanced receivers, MIMO, Continuous Packet Connectivity, Higher-Order Modulation and One Tunnel Architecture, many of which are included in the standardization of 3GPP Release 7 and Release 8.Depending on the features implemented, HSPA+ can exceed the capabilities of IEEE 802.16e-2005 (Mobile WiMAX Release-1) in the same amount of spectrum. Beyond the peak data rate of 42 Mbps for HSPA+ in Release 8 (with 2X2 MIMO, DL 64 QAM and UL 16 QAM), Release 9 may specify 2X2 MIMO in combination with dual-carrier operation, which would further boost peak theoretical downlink network rates to 84 Mbps. In addition to the increased speeds, HSPA+ also will more than double HSPA capacity and has the potential of reducing latency to below 25 milliseconds.
HSPA and HSPA+ will continue to dominate mobile broadband subscriptions worldwide for the remainder of this decade and well into the next. However, announcements have already begun in support of the next 3GPP evolutionary step, LTE. Trials and deployments of LTE will begin in 2010 by leading operators including AT&T, China Mobile, China Telecom, NTT DoCoMo, Verizon and Vodafone. In fact, today there are more than 2 billion subscriptions represented by combining the total existing customer bases of the more than 100 operators, both GSM and CDMA operators, who have announced indications of their intention to deploy LTE networks.
The deployment of LTE and its coexistence with UMTS-HSPA will be analogous to the deployment of UMTS-HSPA and its coexistence with GSM-EDGE.
Whitepaper available to download here.
Accompanying slide presentation available here.
Monday, August 24, 2009
3G or 4G: What should India do?

Last week I wrote about Indian subscribers getting taste of 3G as the state owned MTNL and BSNL have launched some services. I am not sure what has been launched but all I can say is there is a dismal takeup as of yet. I read an article today about how Motorola is testing 4G [sic] and this can spoil the governments plan of rasing Rs 35,000 crore (£4.6Billion: 1Billion = 100 crores).
People may start panicking that investing in 3G is now doomed and it can just cause problems for the operators in future. The reality though is much more simpler. In a simple sentence, I would say that going for 3G or LTE does not matter much. Read on.
Lets first get Hardware out of the way. Most of the Base Stations (NodeB's, eNodeB's, RNC, etc) have a major part as SDR's or Software Defined Radios. The advantage of this is that if you have bought a 3G Node B, with just software change it should be upgradable to LTE eNode B. I have come across quite a few products where the equipment manufacturers are claiming that their 3G equipment is fully upgradeable to LTE. I did blog about some of this in this post here.
The second point we should get out of the way is the terminology. For a layman, 3G is something that was introduced 10 years back in 2000 so its quite an obsolete technology. In reality, 3G is commonly used to refer to even the new developments within the 3G spectrum. For example some of the people may have heard of HSDPA which is actually referred to as 3.5G in the mobile domain. Similarly we have HSUPA which is 3.75G and so on. The latest development is going on around 3.8G and 3.85G as part of Release 8. In general usage 3.5G, 3.75G, etc. is referred to as 3G but its more than 3G (3G+ ;). The good thing is that this 3G+ is till evolving. Release 8 was finalised in Dec. 2008 and the terminals based on that are still being tested. It should hopefully be available soon.
So whats the difference between LTE and HSPA+ (also known as 3G even though its 3.8/3.85G). Not much I would say from a general users point of view. Please note I am not arguing about the fundamental technologies because 3G+ uses WCDMA and LTE uses OFDMA/SC-FDMA technologies. OFDM based technologies will generally be always superior to WCDMA ones but it doesnt matter much. The main enhancement that has happened with LTE as compared to 3G is that in 3G the bandwidth is fixed to 5MHz whereas in case of LTE the bandwidth is flexible and can go all the way to 20MHz. Now if we compare the data speeds in 5MHz spectrum then there may not be much difference between them. Now how many operators will be rolling out services across 20MHz bandwidth? More general case will be using 10MHz.
In case of HSPA+, there is a new feature that allows a UE to use couple of cells. In this case even though the bandwidth is 5MHz but due to Dual Cell feature the UE would effectively see 10MHz bandwidth. This will definitely enhance the speeds.
Now coming to devices. 3G/HSPA/HSPA+ technologies have evolved over quite few years. There are some nice sleek and cheap handsets available. The technology in it as been rigourously tested. As a result the handsets are quite stable and many different design and models available.
LTE is yet to come. NTT DoCoMo and Verizon will be the first one to roll it out probably end 2010. Initial plan is to roll out the dongles then handsets will the eventually arrive. The initial ones will have problems, crashes, etc. Will take atleast till 2010 to sort out everything.
The big problem with LTE as many of us know is that the standards have to support for the old style CS voice and SMS. This should be fixed in Release 9 which is going to be standardised in Dec. 2009 (Mar. 2010 practically). There are different approaches and maybe untill LTE is rolled out we wont know which of them is better.
Last thing I should mention is the spectrum. The consensus is that 3G operates in 2.1GHz spectrum mostly worldwide. LTE would initially be deployed in 2.6GHz spectrum. The digital dividend spectrum when it becomes available will also be used for LTE. Most of the devices for LTE will be designed that way. As a result, 3G will continue to operate as it is in the 2.1GHz band. The devices will always be available and will be usable for long time.
Considering all the facts above, I think 3G (HSPA/HSPA+) is the best option in India or as a matter of fact in any country that is thinking of jumping directly from 2G to LTE. When the time is right, it should not be difficult to move from 3G to LTE.
Friday, April 10, 2009
HSPA based Laptop Enabler/Disabler

Ericsson's F3607gw mobile-broadband module for HSPA/GPRS/EDGE networks, to be released in June, will provide enhanced functionality and convenience through its innovative features, reduced power consumption, prolonged battery life and an increased level of integration, reducing the number of necessary components and therefore cost. The new module will also provide built-in mobile broadband support for Microsoft Windows 7.
Mats Norin, Vice President of Ericsson Mobile Broadband Modules, says: "The combination of leading technology and innovative design in the next-generation module is key to delivering a superior user experience at an affordable price. This module release confirms Ericsson's commitment to making the benefits of connectivity available to everyone."

Operators can also combine the wake-on wireless feature and embedded GPS functionality to create a range of differentiating services for consumers and the enterprise market, including remote manageability, security updates, asset protection and tracking and geo-fencing. The module can also be used for content push services, such as podcasts, public warnings, traffic updates and database updates.
Specifically, the wake-on wireless feature supports security solutions based on Intel's Anti-Theft PC Protection Technology. An anti-theft management service in the network can send a message via SMS to the mobile-broadband module inside the notebook, which securely transfers the message to Intel's Anti-Theft function inside the processor platform. This takes appropriate actions, such as completely locking the computer and making it unusable. When the notebook is located and recovered, an unlock message can be sent to the notebook that makes the data accessible again.
Thursday, April 2, 2009
Fundamental difference between HSDPA and HSUPA

- In the downlink, the shared resource is transmission power and the code space, both of which are located in one central node, the NodeB. In the uplink, the shared resource is the amount of allowed uplink interference, which depends on the transmission power of multiple distributed nodes, the UEs.
- The scheduler and the transmission buffers are located in the same node in the downlink, while in the uplink the scheduler is located in the NodeB while the data buffers are distributed in the UEs. Hence, the UEs need to signal buffer status information to the scheduler.
- The WCDMA uplink, also with Enhanced Uplink, is inherently non-orthogonal, and subject to interference between uplink transmissions within the same cell. This is in contrast to the downlink, where different transmitted channels are orthogonal. Fast power control is therefore essential for the uplink to handle the near-far problem. The E-DCH is transmitted with a power offset relative to the power-controlled uplink control channel and by adjusting the maximum allowed power offset, the scheduler can control the E-DCH data rate. This is in contrast to HSDPA, where a (more or less) constant transmission power with rate adaptation is used.
- Soft handover is supported by the E-DCH. Receiving data from a terminal in multiple cells is fundamentally beneficial as it provides diversity, while transmission from multiple cells in case of HSDPA is cumbersome and with questionable benefits as discussed in the previous chapter. Soft handover also implies power control by multiple cells, which is necessary to limit the amount of interference generated in neighbouring cells and to maintain backward compatibility and coexistence with UE not using the E-DCH for data transmission.
- In the downlink, higher-order modulation, which trades power efficiency for bandwidth efficiency, is useful to provide high data rates in some situations, for example when the scheduler has assigned a small number of channelization codes for a transmission but the amount of available transmission power is relatively high. The situation in the uplink is different; there is no need to share channelization codes between users and the channel coding rates are therefore typically lower than for the downlink. Hence, unlike the downlink, higher order modulation is less useful in the uplink macro-cells and therefore not part of the first release of enhanced uplink.
Saturday, March 28, 2009
Implementation of CQI Reporting in HSPA

The CQI measurement is implemented in the HSPA module and the measurement interval as well as the influence of measurement errors can be parameterised. The results can be given in form of maps or in a statistical manner as histogram for each cell.
Information about the instantaneous channel quality at the UE is typically obtained through a 5-bit Channel-Quality Indicator (CQI) in HS-SCCH, which each UE feed back to the NodeB at regular intervals. The CQI is calculated at the UE based on the signal-to-noise ratio of the received common pilot. Instead of expressing the CQI as a received signal quality, the CQI is expressed as a recommended transport-block size, taking into account also the receiver performance.
The reason for not reporting an explicit channel-quality measure is that different UEs might support different data rates in identical environments, depending on the exact receiver implementation. By reporting the data rate rather than an explicit channel-quality measure, the fact that a UE has a relatively better receiver can be utilized to provide better service (higher data rates) to such a UE. It is interesting to note that this provides a benefit with advanced receiver structures for the end user.
This is appropriate as the quantity of relevance is the instantaneous data rate a terminal can support rather than the channel quality alone. Hence, a terminal with a more advanced receiver, being able to receive data at a higher rate at the same channel quality, will report a larger CQI than a terminal with a less advanced receiver, all other conditions being identical.
Each 5-bit CQI value corresponds to a given transport-block size, modulation scheme, and number of channelization codes. Different tables are used for different UE categories as a UE shall not report a CQI exceeding its capabilities. For example, a UE only supporting 5 codes shall n

The CQI values listed are sorted in ascending order and the UE shall report the highest CQI for which transmission with parameters corresponding to the CQI result in a block error probability not exceeding 10%.
Specifying which interval the CQI relates to allows the NodeB to track changes in the channel quality between the CQI reports by using the power control commands for the associated downlink (F-) DPCH. The rate of the channel-quality reporting is configurable in the range of one report per 2–160 ms. The CQI reporting can also be switched off completely.
In addition to the instantaneous channel quality, the scheduler implementation in the NodeB should typically also take buffer status and priority levels into account before finalising the data rate for the UE. Obviously UEs for which there is no data awaiting transmission should not be scheduled. There could also be data that is important to transmit within a certain maximum delay, regardless of the channel conditions. One important example hereof is RRC signalling, for example, related to cell change in order to support mobility, which should be delivered to the UE as soon as possible. Another example, although not as time critical as RRC signalling, is streaming services, which has an upper limit on the acceptable delay of a packet to ensure a constant average data rate. To support priority handling in the scheduling decision, a set of priority queues is defined into which the data is inserted according to the priority of the data. The scheduler selects data from these priority queues for transmission based on the channel conditions, the priority of the queue, and any other relevant information.