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Finally, fresh out of the virtual press, the Carnival of the Mobilists has appeared this week on Howard Rheingold’s Smart Mobs blog. Written by Judy Breck, the Carnival contains an overview of the best blog entries on mobile topics published by mobile enthusiasts all over the world in the previous week. So head over and enjoy!

Today I read a post on Teltarif, a German website, that FON has partnered with a German DSL reseller to offer bundles for prospective Foneros. For those of you who haven’t heard of FON before, they are attempting to build the largest Wifi Hotspot network in the world with the help of private enthusiasts.

I like the idea of bundling FON with a DSL offer, as I think becoming a Fonero must be as easy as possible in order to be successful. At closer inspection, however, the bundle falls short of the "Buy our product and we will deliver a box which you just have to plug into your phone socket at home to become a hotspot". Instead, the offer only bundles a FON account, a Fon Wifi access point and a DSL data subscription provided by Interroute Germany.

What’s missing is the DSL line subscription and a DSL modem which you have to get separately. Apart from being too complicated for the average user who’s thinking about becoming a Fonero because he lives downtown or near a hotel, the hardware lineup is also not reflecting todays DSL landscape. While it was common to have a separate DSL modem and a separate Wifi router a couple of years ago, integrated Wifi routers + DSL modems are the norm these days.

Great first step FON, but now it’s time to put your software on an integrated Wifi router / DSL modem and find a reseller who is willing to do the final step and sell both the DSL data subscription and the DSL line in one package.

As a frequent traveler, I’m amazed that each country seems to have it’s oddities when it comes to mobile carriers. In some countries, mobile voice and mobile data is very cheap while in others just accross the border, the world looks quite different. Debi Jones of MobileJones.com and Mediaslaves has been nice enough to do the first in a series of podcasts discussing the state of wireless in different countries. Debi lives in California, so the US mobile landscape is the center of our discussions:

Part 1:

• Coexistence of GSM and CDMA in the US
• HSDPA deployment
• Closed down CDMA handsets
• The Nokia vs. Qualcomm battle
• The Korean CDMA/UMTS situation
• Price of wireless data

Podcast, MP3, 26 mins, 12 MB

Part 2:

• Muni Wifi and combination of Cellular and Wifi Data plans
• Wireless traveling in the US
• A hotspot detector (check it out at CanaryWireless.com)
• Wireless Instant Messaging, Yahoo Go!, Skype and Trillian
• Verizon’s Walled Garden
• Mobile phone multitasking on Nokia N-Series phones
• Mobile phone design

Podcast, MP3, 28 mins, 13 MB

Sometimes I find it really strange that a large part of wireless networks is everything but wireless. The only part which is really "wireless" is the radio channel between the user and the cell tower. Behind the base station data and voice is transferred over copper or fiber cables, or microwave links in some cases.

Kevin has come up with an interesting whitepaper on the evolution of the transmission network behind the base stations which is required to adapt the networks to the increasing demand for mobile data. Among many other things the following figures were quite interesting to me, especially when combined with an earlier post of mine on data usage of a mobile PC user and potential revenue generated per base station:

• Cost of Running the Network: The percentage for running the network from the total operational expenditure (OPEX) is around 30%. On the other hand, 43% of the money goes to Marketing, Sales and Administration… (see figure 2 in the whitepaper). I wonder if (and where) the salaries of the various top executives (CEO, CTO, CMO,…) are included in the OPEX!? 😉

• Backhaul Line Rental: On page 4, the whitepaper says that the line rental for a 2 MBit/s E-1 link used for most UMTS base stations today is about € 250.- per month. This amounts to about 1/3 of the 30% spent from the total OPEX on network operation.

• Cost for Technical Personnel: The costs for technical personnel to run the network amounts to another third of the network operation costs. This is 10% of the overall OPEX. Not very much compared to the 43% for Marketing, Sales and Administration…

Kevin Evans has put a post on his blog on HSDPA backhaul over ADSL. At first, it seems like a pretty good idea he says but has some second thoughts:

Kevin says Internet Service Providers (ISP) would probably be less than happy to connect HSDPA ADSL links to their  backbone. I agree! Cells where HSDPA is used heavily will pretty much use most of the bandwidth of an ADSL link for a considerable time per day. Consequently, such links would substantially increase the load of the ISPs ADSL backbone.

He then goes on to say that the alternative for mobile operators is to do their own ADSL backhauling. He thinks this is also not a good idea due to having to build an overlay network for backhauling next to the E-1s currently used for real time voice traffic. But why is it such a bad idea for operators to put their own ‘mini’ DSLAMs in central offices and have a little fiber there for backhauling? There is cost whatever you do, E-1, microwave, etc. so why not ADSL?

Some operators might have already decided to do this (speculation on my part). O2 Germany for example has said that they want to become an integrated fixed- and mobile telecommunication company, providing both high speed fixed line Internet access via DSL and high speed mobile Internet access via HSDPA. If they decide to build their own ADSL network, they can use it for both purposes.

As an alternative, Kevin suggests to use Ethernet for carrying both real time voice traffic and non real time background and streaming traffic generated by web browsing, podcast downloads, etc. But what about the distance you can cover with commercial Ethernet equipment today over phone cables?

When I first read about HSDPA over ADSL backhaul it immediately made sense to me due to the fact that ADSL has become a cheap technology to bridge larger distances than what is possible with other technologies. Have new long distance Ethernet technologies caught up in the meantime?

Whatever operators decide, I hope they decide quickly as HSDPA over 2 MBit/s E-1s is not going to make people happy.

Silently, my fellow co-worker Pierre Lescuyer has updated his excellent book on UMTS called "Réseaux 3G" (3G networks) and the 3rd edition is now available in French. The new edition contains among other additions new chapters on HSDPA, HSUPA, IMS and MMS. Previous editions are also available in English and German.

Very well done, Pierre, congratulations!

The Carnival has returned to it’s founders blog at MobHappy and I’ve never seen so many great articles as in this one. So if you are looking for a place to discover new things and thoughts about mobile from the blogsphere, head on over.

All answers have been held as short as possible and require an understanding and study of the corresponding chapter of the book.

Answer 1:

The basic concept of the 5G Non-Standalone architecture is to add a 5G NR cell as a speed booster to an existing LTE radio and core network. It is different from LTE carrier aggregation as the 5G cell acts independently from the LTE part of the connection. Data is transmitted over LTE and 5G NR simultaneously.

Answer 2:

TDD = Time Division Duplex, e.g. used in band n78. Uplink and downlink are transmitted over the same channel. FDD = Frequency Division Duplex, typically used in frequency bands in Europe < 3 GHz. Uplink and Downlink are separated in the frequency domain, i.e. they use different channels. Hence, uplink and downlink are transmitted simultaneously.

Answer 3:

In 5G NSA, data is transmitted over LTE and 5G NR at the same time. Typically the 5G gNB receives the data, splits a apart of it away and forwards it to the LTE part of the connection while it transfers another part itself.

Answer 4:

In the uplink direction LTE and 5G use different frequencies and one transmitter in the UE is required for each channel as data is transferred simultaneously over both legs of the connection in the uplink direction.

Answer 5:

In 5G NR, a UE does not necessarily need to support the full channel bandwidth and can be assigned only a part of the channel on the frequency axis. Also, a network might decide to assign different bandwidth parts to a UE to conserve power with a narrow BWP while only small amounts of data are transferred.

Answer 6:

The CORESET is the Control Region Set, i.e. the control regions the UE has to monitor on the channel for uplink and downlink assignments.

Answer 7:

Dynamic Spectrum Sharing (DSS) can be used to transmit LTE and 5G NR on the same channel. This way, the channel can serve older LTE only mobiles and newer 5G NR mobiles. This is done by transmitting the control channels of LTE and 5G NR in the channel at different times and by using several methods and signaling alignments for 5G NR devices to only notice the 5G transmissions while LTE devices only see the LTE signaling channels and reference signals.

Answer 8:

The LTE eNB and 5G NR gNB have independent schedulers and communicate over the X2 interface which each other. This way, handovers can be made independently as only the X2 connection is switched. In practice it often occurs that the LTE and 5G NR parts are served by different sites. The uplink/downlink data is split/combined at one of the two sites.

Answer 9:

The idea behind the Service Oriented Architecture is to leverage container technology in combination with microservices and stateless communication to build a highly adaptable, configurable and scalable 5G core network.

Answer 10:

5G registration management is performed by the Access Management Function and deals with authentication of subscribers and managing their presence in the network. Session management on the other hand is managed by the Session Management Function and deals with the establishment with user plane bearers between the mobile device and an external network such as the Internet.

Answer 11:

In RRC-Idle state, no active connection exists between the mobile device and the gNB over the air interface. Also, the signaling connection and the user data tunnel to the core network have been removed. In RRC-Inactive state, only the air interface connection is removed while the connection between the gNB and the core network remains in place. This significantly reduces signaling when connectivity needs to be restored.

Answer 12:

The idea of Network Slicing is to have a single end to end network and serve devices with different requirements in different ways. On the air interface, different parts of the channel can use different configurations. One part of the channel could be used for fast Internet access, while another part, that is configured differently could be used for slow but very reliable communication. Other parts of the network can be sliced in a similar manner.

Again a great summary of this week’s best blog entries on wireless in the Carnival of the Mobilists. This week the Carnival is hosted at the Digital Evangelists blog, so head over and check it out!