Chris 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.
Chris 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.
Currently, 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.
Chris 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.
Hello All,
Sorry for my lack of blogging lately. Projects can be tough. With the apologies out of the way, I had a colleague ask a couple of questions 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 band size. In LTE there is a scalable OFDM channel. The bandwidth can vary from 1.4 MHz to 20 MHz. There are also a number of frequency bands that are going to be used for LTE (the new 700 MHz as well as the old PCS and Cellular bands).
The question basically was can a mobile move between frequency bands and the answer is absolutely yes. The second part of the question regarded movement between different sizes of bands. The best way to approach this question is to define two terms. The two terms are intra-frequency and inter-frequency mobility. We are use to these terms in other technologies (i.e. GSM and UMTS), but LTE puts a new spin on things. Intra-frequency mobility is when a mobile moves between two cells and both cells have the same frequencies (I 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 that is only a few miles away this same operator has only 5 MHz available in the 850 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 mobile will have to do inter-frequency mobility measurements to provide information on the new cells signal strength.
The reason this is an important discussion is that when the mobile does intra-frequency measurements the network does not need to allow any time to do the measurements. The mobile can just do them whenever they want to. For inter-frequency measurements the mobile must be given time to stop listening to its current cell and listen to a new cell to take the measurements. That increases the level of complexity and the amount of work the mobile will need to do.
I hope this helps give some insight into mobility. Please feel free to send questions if you have any.
Take care,
Chris
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