joined Award Solutions in 2000, bringing his expertise in GSM and IS-136
technologies and wireless network planning. He specializes in
telecommunications systems, focusing in GSM, GPRS, and UMTS systems, wireless
and Internet applications, and the convergence of communication technologies.
Currently, he is working on LTE, UMTS, IP Multimedia Subsystem, IP telephony,
HSPA+, and Wireless Network Planning. He has over 19 years of experience in the
wireless telecom industry.
began his career in the wireless telecommunication industry. He spent the first
nine years in the Wireless Systems Engineering department at Nortel Networks.
As a Member of Scientific Staff, Chris worked on network planning, customer
support, bid support, and capacity planning for low power wireless systems and
Personal Communications Systems. He moved into the GSM and IS-136 field as a
manager. These responsibilities included working with customers to plan,
expand, and manage their existing wireless network. This position evolved into
managing the GSM, IS-136 and IS-95 core network capacity team as a Senior
Manager. In the role of Senior Manager, Chris worked with the development
teams, product test teams, marketing teams, and product line management teams
in the determination and requirement establishment of the subscriber capacity
of these systems. This included presenting capacity information directly to
customers and influencing them in their network evolution direction.
Chris is a Principal Consultant at Award Solutions. His current focus is LTE,
4G, OFDMA, UMTS/HSPA+, IP convergence, and Network Planning. His interests
include the planning of the LTE radio network and core network; service
planning in the LTE core network and mobile devices; and interoperations and
mobility between LTE and the 3G networks. He is also responsible for helping in
the mentoring of new instructors in UMTS and LTE.
holds a Master's degree in Computer Science Telecommunications from the
University of Missouri at Kansas City as well as Bachelor's degree in Computer
Science and Mathematics from Cameron University. Chris also holds 4 patents in
the area of wireless technology.
Sorry for my lack of blogging lately. Projects can
With the apologies out of the way, I had a colleague ask a couple of
recently and I thought it would be good to share the answers with LTE-U.
His main question was about mobility. Mobility in
LTE can be
quite tricky. The main point of his question was about the frequency
In LTE there is a scalable OFDM channel. The bandwidth can vary from 1.4
20 MHz. There are also a number of frequency bands that are going to be
for LTE (the new 700 MHz as well as the old PCS and Cellular bands).
The question basically was can a mobile move
frequency bands and the answer is absolutely yes. The second part of the
regarded movement between different sizes of bands. The best way to
this question is to define two terms. The two terms are intra-frequency
inter-frequency mobility. We are use to these terms in other
GSM and UMTS), but LTE puts a new spin on things. Intra-frequency
when a mobile moves between two cells and both cells have the same
know, not the most profound statement). If there is a change in the center
frequency this is now called
inter-frequency mobility. In
LTE both intra-frequency and inter-frequency mobility are supported. (5/4/10 Note - I has come to my attention that if the bandwidth changes, but the center frequency does not change it is still a intra-frequency handover.)
For example, let's say that an operator has in one
city a 10
MHz block in the 850 MHz band that they are using for LTE. In a city
only a few miles away this same operator has only 5 MHz available in the
MHz band. When a subscriber drives from city A to city B the size of the
frequency band is changing (as will probably the DC carrier) and the
will have to do inter-frequency mobility measurements to provide
the new cells signal strength.
The reason this is an important discussion is that
mobile does intra-frequency measurements the network does not need to
time to do the measurements. The mobile can just do them whenever they
For inter-frequency measurements the mobile must be given time to stop
to its current cell and listen to a new cell to take the measurements.
the level of complexity and the amount of work the mobile will need to
I hope this helps give some insight into mobility.
feel free to send questions if you have any.
Very interesting. Thanks for the useful information. I have a question about Carrier Aggregation (CA) in LTE-Advanced. Many of the issues you mentioned would get more complex for handover of a UE that supports CA, right? More generally, can a UE receiver process RF signals in two different bands (with different center frequencies) simulateneously?
very good answer. Thanks for this information. How to refer to it, if I have cite from this answer or other tutorials that you are provided?
Hi Chris! Thanks for the article. I know it's been a while since you wrote this but I have found a similar issue in a customer network. The customer has deployed on 10Mhz and has started to introduce Mixed Mode LTE sites which are 5Mhz bandwidth. These have the same center frequency so it should be a intra-frequency handover. My question is how the UE behaves in this situation, in particular the way it measures the 5Mhz neighbor. If you are in rrc connected and moving towards the 5Mhz cell, how will the UE know to measure the 25 RB's instead of 50? We have the parameter "allowedMeasBandwidth" that is set to match the channel bandwidth of the cell, so does the UE read the SIB's of the neighbor cell to determine the "allowedMeasBandwidth"? Any insight would be helpful. Thanks