October 2012
Intermediate to advanced
248 pages
7h 54m
English
Content preview from LTE Advanced: 3GPP Solution for IMT-AdvancedBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
7.4 Physical Layer Impacts from Uplink MIMO
Moving from a single antenna transmission to two- or four-transmitter antennas required some partly new structures in the physical layer. It also required consideration for the resulting impact to the signal waveform properties. Also, the reference signal structure needed modification to cover the case of multiple transmit antennas per UE as well as to enable better use of the MU-MIMO functionality.
7.4.1 Uplink Reference Signal Structure
In the uplink direction there are two additional solutions introduced to the reference signal structure:
- Orthogonal Cover Codes (OCC) to complement the use of cyclic shifts of the Demodulation Reference Signal (DM RS) sequence;
- Aperiodic Sounding Reference Signal (SRS) to enhance the use of available SRS resources.
Both features are beneficial not only for SU-MIMO UEs but also for UEs with single transmit antenna.
Orthogonal cover codes are length-2 Walsh codes extended over the two DM RS in the subframe as shown in Figure 7.4. OCCs provide two benefits: they improve the reliability in separating the different RS from each other, especially when SU-MIMO or MU-MIMO transmission contains several transmission layers. Additionally, two DM RSs that overlap only partially in frequency are sufficiently separated. This is not the case when DM RS are separated by cyclic shifts. This feature is especially beneficial in the case of MU-MIMO, as now the PRB allocations of the paired UEs do not need to be fully ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.