The auction of the UHF band (700MHz) last year caused quite a stir in the industry. The “Open Access” can was opened, Google flexed muscles during the bidding process, and the analogue TV finally got the last nail in the coffin. Long after the dust had settled, I had an “Oersted-moment” during one of my Wireless Technology classes about block C of this band which is known as E-UTRA Band 13 in the 3GPP specifications. This block is assigned for LTE operations by Verizon Wireless in their upcoming LTE deployment.
Now, the “Oersted-Moment”; The Dane H.C. Oersted is the guy who discovered that electric currents can create magnetic fields. Just moments before starting a public lecture in April 1820, he noticed the current in a wire can deflect the needle in a compass that was lying around. He changed the subject of the lecture on the fly and started to explain (correctly) the phenomena he had just observed to the oblivious public who were witness to the birth of Electromagnetism!
Well, I’m afraid my “discovery” is not going to make it in any history book nor is it going to start a new science. But it was in a classroom, after I had opened Technical Specification 36.101 for handset radio transmission and reception that I suddenly noticed for the first time something odd about Band 13. The table is in below, and you can try to spot it before you go on reading….
|
E-UTRA Band
|
Uplink (UL)
eNode B receive
UE transmit
|
Downlink (DL)
eNode B transmit
UE receive
|
|
Duplex Mode
|
|
|
FUL_low - FUL_high
|
FDL_low - FDL_high
|
|
|
|
|
1
|
1920 MHz
|
-
|
1980 MHz
|
2110 MHz
|
-
|
2170 MHz
|
|
FDD
|
|
|
2
|
1850 MHz
|
-
|
1910 MHz
|
1930 MHz
|
-
|
1990 MHz
|
|
FDD
|
|
|
3
|
1710 MHz
|
-
|
1785 MHz
|
1805 MHz
|
-
|
1880 MHz
|
|
FDD
|
|
|
4
|
1710 MHz
|
-
|
1755 MHz
|
2110 MHz
|
-
|
2155 MHz
|
|
FDD
|
|
|
5
|
824 MHz
|
-
|
849 MHz
|
869 MHz
|
-
|
894MHz
|
|
FDD
|
|
|
6
|
830 MHz
|
-
|
840 MHz
|
875 MHz
|
-
|
885 MHz
|
|
FDD
|
|
|
7
|
2500 MHz
|
-
|
2570 MHz
|
2620 MHz
|
-
|
2690 MHz
|
|
FDD
|
|
|
8
|
880 MHz
|
-
|
915 MHz
|
925 MHz
|
-
|
960 MHz
|
|
FDD
|
|
|
9
|
1749.9 MHz
|
-
|
1784.9 MHz
|
1844.9 MHz
|
-
|
1879.9 MHz
|
|
FDD
|
|
|
10
|
1710 MHz
|
-
|
1770 MHz
|
2110 MHz
|
-
|
2170 MHz
|
|
FDD
|
|
|
11
|
1427.9 MHz
|
-
|
1452.9 MHz
|
1475.9 MHz
|
-
|
1500.9 MHz
|
|
FDD
|
|
|
12
|
698 MHz
|
-
|
716 MHz
|
728 MHz
|
-
|
746 MHz
|
|
FDD
|
|
|
13
|
777 MHz
|
-
|
787 MHz
|
746 MHz
|
-
|
756 MHz
|
|
FDD
|
|
|
14
|
788 MHz
|
-
|
798 MHz
|
758 MHz
|
-
|
768 MHz
|
|
FDD
|
|
|
...
|
|
|
|
|
|
|
|
|
|
|
17
|
704 MHz
|
-
|
716 MHz
|
734 MHz
|
-
|
746 MHz
|
|
FDD
|
|
|
...
|
|
|
|
|
|
|
|
|
|
|
33
|
1900 MHz
|
-
|
1920 MHz
|
1900 MHz
|
-
|
1920 MHz
|
|
TDD
|
|
|
34
|
2010 MHz
|
-
|
2025 MHz
|
2010 MHz
|
-
|
2025 MHz
|
|
TDD
|
|
|
35
|
1850 MHz
|
-
|
1910 MHz
|
1850 MHz
|
-
|
1910 MHz
|
|
TDD
|
|
|
36
|
1930 MHz
|
-
|
1990 MHz
|
1930 MHz
|
-
|
1990 MHz
|
|
TDD
|
|
|
37
|
1910 MHz
|
-
|
1930 MHz
|
1910 MHz
|
-
|
1930 MHz
|
|
TDD
|
|
|
38
|
2570 MHz
|
-
|
2620 MHz
|
2570 MHz
|
-
|
2620 MHz
|
|
TDD
|
|
|
39
|
1880 MHz
|
-
|
1920 MHz
|
1880 MHz
|
-
|
1920 MHz
|
|
TDD
|
|
|
40
|
2300 MHz
|
-
|
2400 MHz
|
2300 MHz
|
-
|
2400 MHz
|
|
TDD
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
“And as you can see…” I said to the class without hesitation, Band 13 has the uplink and downlink reversed! In contrast to all other FDD bands in the table (and many other bandplans elsewhere), in this band, the higher frequency is allocated to the mobile device and the lower frequency to the base station. The normal practice of FDD paired band allocation has to do with attenuation properties of the carrier frequency and the availability of the power. The mobile side has usually been allocated the “easier” lower-frequency portion of the band which experiences smaller amount of attenuation and therefore requires less power for closing the uplink. A reversal of this allocation strategy in band 13 is a sure sign that some other problem is lurking in the background, namely interference in the form of spurious emissions.
The 700MHz band is divided into four paired blocks, A, B, C and D (an unpaired E Block is also available). The A and B blocks are guard bands. The C blocks (LTE Band 13) in this upper 700MHz band were the main object of last year’s auction. 12MHz in the middle of this spectrum belongs to the Public Safety.
A – C – D – B – [Public Safety] – A – C – D - B
A look at the structure of the auctioned UHF band shows that upper portion of Band 13 is closer to the public safety band. In order to reduce the effects of interference to the public safety band and other bands due to intermodulation effects of this carrier, the higher more “difficult” frequency has been allocated to the lower powered handset. On the other hand we can expect a slight enhancement in indoor coverage for band 13, due to further lowering of the downlink frequency .The question to ask is if this maneuver is enough to suppress the spurious emissions caused by the handsets to nearby bands. Further details after initial deployment will shed light on the mysterious case of band 13.
/Hooman
Posted
07-24-2009 8:17 PM
by
Hooman Razani