Monday, 14 May 2012

Location Services in LTE Networks

Recently made a combined architecture of LTE with LCS and MBMS and posted it here. This document from MSF below looks at the LoCation Services (LCS) in detail.

Saturday, 12 May 2012

A Twitter discussion on 'Data Tsunami' myth




Participants:


@disruptivedean - Dean Bubley
@StevenJCrowley - Steve Crowley
@WhatTheBit - Stefan Constantine
@labboudles - Leila Abboud
@twehmeier - Thomas Wehmeier
@jamncl4 - Jonathan Morgan
@wifidave - Dave Wright



@disruptivedean: Data tsunami myth washing further out to sea: Telefonica mobile data grew 35% YoY to Q1, vs. data rev growth of 28%. http://www.telefonica.com/en/shareholders_investors/html/financyreg/resultados2012.shtml


@disruptivedean: Increasingly convinced that some cellular data growth numbers & forecasts are over-inflated - mainly to sway regulators on spectrum policy

@StevenJCrowley: Wonder how much of Telefonica lower data growth is from Spain's unusually bad economy versus normal "S curve"

@twehmeier: Did you see that shockingly unbalanced story on data traffic in FT? Pure spin. Telefonica is v representative of Euro ops. The other factor is vendors perpetuating the myth to sell their products and services

@WhatTheBit: you should do some research into operator spectrum holdings versus actual utilization, I'm sure the results would B shocking

@twehmeier: The other factor is vendors perpetuating the myth to sell their products and services

@disruptivedean: Don't think Spanish economy that much an issue. Growth been flattening in UK & Germany for a while - http://disruptivewireless.blogspot.co.uk/2011/11/smoking-gun-i-think-o2-uk-has-falling.html


@disruptivedean: The contrast in attitude between TF corporate vs. TF Digital is striking sometimes.

@labboudles: that's interesting, is it typical of others ops numbers, ie data makes them money so stop whining abt capex/google?

@disruptivedean: It's certainly true for VF in Europe - they have faster data rev growth than traffic growth. Caps/tiers fixed the problem


@disruptivedean: Basic pricing tiers/caps + user-controlled WiFi have "fixed" the problem. Has undermined need for more complex solutions & tech

@twehmeier: Indeed. amazes me how little emphasis placed on imprtnce of pricing. Next prob will be working out how to bring traffic back

@disruptivedean: Yes, especially with LTE - in some places/networks we're heading for overcapacity. Not quite as bad as fibre in 2001, but scary

@twehmeier: And that will likely lead to more naive pricing models that only serve to accelerate self-commoditisation of value of data!


@twehmeier: Telenor firsy reported faster data revenue growth versus traffic back in 2010. And that's in some of the world's most advanced smartphone and MBB markets...

@labboudles: thought so since that was case in France, but admit had not looked at all ops trends

@disruptivedean: Also beware that some operators (eg AT&T) have started adding in WiFi hotspot traffic to bump up the numbers

@twehmeier: Shameless lobbying....

@labboudles: where is there overcapacity?! Places where LTE has been built and already used?

@twehmeier: imagine a market where Wi-Fi is ubiquitous and all operators deploy LTE on top of pre-existing HSPA/HSPA+. And remember average utilisation of European 3G networks is typically only in the 35-40% range and pretty steady

@labboudles: that's a ways off in real world though


@labboudles: ok that I just don't understand, then why is my user experience of mobile Internet so crap n London, Paris ?

@disruptivedean: Depends how you calculate it. Bear in mind many MNOs don't "light up" all spectrum initially, but add extra capacity


@disruptivedean: Plenty of other bottlenecks - most notable is poor coverage, could be backhaul, stuff in core network, even DNS etc


@disruptivedean: Congestion often caused by too much signalling (setting up/tearing down IP conxns), not sheer data "tonnage"

@jamncl4: Actually I think we are also seeing the impact of the shift from laptops to tablets and smartphones


@jamncl4: People can't afford multiple data plans so they shift from laptop to Smartphones which inherently use less data

@wifidave: How did you arrive at 35%/28%? I found 15.4% YoY in "mobile data revenue", and couldn't find traffic figures.

@jamncl4: Same with tablets which also pull usage away from laptop except most tablets are wifi only


@jamncl4: WiFi is in enough places that I can't justify two data plans so I stick to wifi tablet and data pla smartphone

@disruptivedean: It's on page 6 of the results presentation, showing rapid convergence of traffic & revenue growth

@jamncl4: The smartphone will take a few years to catch up to laptops in terms of data requirements thus "slowdown" growth

@disruptivedean: Bear in mind rising % of people don't have "plans" but use PAYG for data. But yes, dongle traffic falling, phone rising

@jamncl4: But Smartphone require higher signaling than laptops due to apps & power saving techniques;massive signal growth

@disruptivedean: Tablet/laptop substitution (or not) largely irrelevant as both are generally WiFi-only & will most likely stay that way

@jamncl4: Multi device plans could be interesting moving forward and there impact on this


@jamncl4: I disagree. Majority of traffic has come from laptops in past so more wifi & tablets reduces the traffic

@wifidave: @disruptivedean OK, I see. The 27% is a subset of the 15.4%.

@jamncl4: I think the real issue is that people don't want to pay for 2 plans & the 1 plan in general is Smartphone for now. Multidevice PAYG plans will be interesting on their impact.

@wifidave: Ponder this > Assuming TF #s are cell data, they represent a mobile data Traffic/Rev YoY growth ratio of 1.29:1 . The same ratio for #ChinaMobile in Q4'11 was 1.28:1 . For #ChinaMobile, cell data grew at 56.1% traffic and 43.5% revenues.


@wifidave: ATT says that "wireless data traffic" doubled in 2011 from 2010. (http://www.attinnovationspace.com/innovation/story/a7781181). but elsewhere report that their Wi-Fi traffic increased 550% in Q4'11. (http://www.vision2mobile.com/news/2012/01/wif.aspx). all while wireless data revenues only grew 19.4% YoY in Q4'11 (http://www.att.com/gen/press-room?pid=22304&cdvn=news&newsarticleid=33762)


@wifidave: The real growth (337% and 550% for CM and ATT) is in Wi-Fi as Dean said. Not adding much to rev yet.

@disruptivedean: Absolutely agree more WiFi = less "big device mobile data traffic". Unconvinced it matters if big device = laptop/tablet


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Friday, 11 May 2012

Tuesday, 8 May 2012

WiFi: Standards, Spectrum and Deployment

Yesterday, IEEE published its fourth revision to 802.11. The updates include faster throughput, improved cellular hand-offs, and better communication between vehicles in addition to other improvements.The following from IEEE website:

The new IEEE 802.11-2012 revision1 has been expanded significantly by supporting devices and networks that are faster, more secure, while offering improved Quality of Service and, improved cellular network hand-off. IEEE 802.11 standards, often referred to as “Wi-Fi®,” already underpin wireless networking applications around the world, such as wireless access to the Internet from offices, homes, airports, hotels, restaurants, trains and aircraft around the world. The standard’s relevance continues to expand with the emergence of new applications, such as the smart grid, which augments the facility for electricity generation, distribution, delivery and consumption with a two-way, end-to-end network for communications and control.

IEEE 802.11 defines one MAC and several PHY specifications for wireless connectivity for fixed, portable and mobile stations. IEEE 802.11-2012 is the fourth revision of the standard to be released since its initial publication in 1997. In addition to incorporating various technical updates and enhancements, IEEE 802.11-2012 consolidates 10 amendments to the base standard that were approved since IEEE 802.11’s last full revision, in 2007. IEEE 802.11n™, for example, defined MAC and PHY modifications to enable much higher throughputs, with a maximum of 600Mb/s; other amendments that have been incorporated into IEEE 802.11-2012 addressed direct-link setup, “fast roam,” radio resource measurement, operation in the 3650-3700MHz band, vehicular environments, mesh networking, security, broadcast/multicast and unicast data delivery, interworking with external networks and network management.

“The new IEEE 802.11 release is the product of an evolutionary process that has played out over five years and drawn on the expertise and efforts of hundreds of participants worldwide. More than 300 voters from a sweeping cross-section of global industry contributed to the new standard, which has roughly doubled in size since its last published revision,” said Bruce Kraemer, chair of the IEEE 802.11 working group. “Every day, about two million products that contain IEEE 802.11-based technology for wireless communications are shipped around the world. Continuous enhancement of the standard has helped drive technical innovation and global market growth. And work on the next generation of IEEE 802.11 already has commenced with a variety of project goals including extensions that will increase the data rate by a factor of 10, improve audio/video delivery, increase range and decrease power consumption.”

1 IEEE 802.11™-2012 “Standard for Information technology--Telecommunications and information exchange between systems Local and metropolitan area networks--Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”


The following is from a presentation by Agilent in LTE World Summit last year. It summarises the 802.11 standards, the Spectrum available and deployment use cases.







Saturday, 5 May 2012

Wednesday, 2 May 2012

LTE 'Antenna Ports' and their Physical mapping

People who work with LTE Physical layer and maybe higher layers would be aware of this term called 'Antenna Ports'. I have always wondered how these antenna ports are mapped to physical antennas.

The following is from R&S whitepaper:

The 3GPP TS 36.211 LTE standard defines antenna ports for the downlink. An antenna port is generally used as a generic term for signal transmission under identical channel conditions. For each LTE operating mode in the downlink direction for which an independent channel is assumed (e.g. SISO vs. MIMO), a separate logical antenna port is defined. LTE symbols that are transmitted via identical antenna ports are subject to the same channel conditions. In order to determine the characteristic channel for an antenna port, a UE must carry out a separate channel estimation for each antenna port. Separate reference signals (pilot signals) that are suitable for estimating the respective channel are defined in the LTE standard for each antenna port. 

Here is my table that I have adapted from the whitepaper and expanded. 




The way in which these logical antenna ports are assigned to the physical transmit antennas of a base station is up to the base station, and can vary between base stations of the same type (because of different operating conditions) and also between base stations from different manufacturers. The base station does not explicitly notify the UE of the mapping that has been carried out, rather the UE must take this into account automatically during demodulation (FIG 2).


If there is another way to show this physical mappings, please feel free to let me know.

The R&S Whitepaper is available here if interested.