Xelerated Xpress

Higher Synchronization Demands, Not Less

My colleague Tord Haulin gave me this brief summary of the synchronization demands as mobile backhaul networks goes packet. You can think of the demands as a three-step evolution:

1. Distribution of precise frequency

Requirement for e.g. WCDMA/UMTS transport equipment: 15 parts per billion (ppb)

This means: OK to deliver up to a dozen too many/too few clock cycles every day (for a 8kHz reference frequency).

2. Distribution of locked frequency with tight phase control

Requirement for e.g. Fixed WIMAX transport equipment 4.3 micro seconds

This means: The precise number of clock cycles has to be delivered every year. It is OK to lead or lag up to a dozen of degrees at any time (also for a 8kHz reference)

3. Distribution of time of day

Requirement for e.g. radio interface of CDMA/CDMA2000: 1 micro second.

This means: Time carrying signal cannot be sent more than 150 m without compensating for transport delay. That would be one city block(!) 

To measure time in distance of speed of light, and frequency wander in lost clock cycles, put the hard mobile infrastructure requirements on frequency, phase and time of day distribution into perspective. For those interested in more details, I recommend taking a look at Xelerated’s precision time solution white paper.

More on this topic will also be presented at the upcoming MPLS & Ethernet World Congress 2010 and Ethernet Wholesale Summit 2010 in Paris, February 9-12, 2010. Xelerated will be there as well as many of our industry peers.

Look forward to seeing you there!

by Per Lembre on Jan. 27th, 2010

| Comment

Dare to Share?

Investing in a new Radio Access Network (RAN) infrastructure is a multi-billion dollar undertaking. When Telia lost the beauty competition for the 3G licences in Sweden for the period of 2001-2015, they decided to cooperate with Tele2 and formed a joint venture, Svenska UMTS-nät, for the 3G RAN network. The model has been copied in a few markets, like Norway, Austria and Australia. For the next generation 4G/LTE network, Tele2 is now cooperating with Telenor in a similar way to the joint venture Net4Mobility.

While there are technical constraints associated with not having full control of network resources, there is an obvious gain in cutting the investment costs in half. Most of the technical limitations are addressed as the technology matures. But the commercial aspect is harder to tackle. Sharing the complete radio network makes differentiation very hard.

This is a multi-billion dollar question, and the jury doesn’t seem to have reached their verdict. Yet.

by Per Lembre on Jan. 19th, 2010

| Comment

4G Or Not 4G, That Is The Question

Ericsson’s and TeliaSonera’s announcement of the first commercial LTE deployment provoked an intensive debate on LinkedIn’s LTE group. Is LTE really 4G, or is it 3.9 or even 3.8?

Few things triggers more discussion than terms and definition. On one hand, you have a group of professionals that believe that the usage of a term has to be defined strictly in technical terms, and if a technology doesn’t meet the definition to 100%, it is non-compliant. Don’t say it is 4G, if it is not compliant to ITU’s definition, they claim.

The other camp, and I belong to this group, simply say that the new generation of technology is defined by both technical and commercial means. The 4th generation of mobile infrastructure is underway. LTE has a completely new air interface and a completely new core. In practice, the backhaul segment is also re-engineered. This is a huge new investment by mobile operators and the consumers have to buy new handheld devices. A new page in the history book of mobile infrastructure is being turned. I call that 4G.

The debate continues though. You can make your opinion heard here.  Or you can consider contributing to the wikipedia definition of 4G.

by Per Lembre on Jan. 8th, 2010

| Comment