Hmmm.
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E1820 External Antenna Connector
- Thread starter Jola
- Start date
ajax
Executive Member
Thanks a million for the post 1geoff99. I was *just* about to load the firmware when I thought to quickly check this thread again...
Ginggs probably couldn't pick this up as his UMTS2100 tower is out of order. Still strange though why the UMTS2100 doesn't work with the "latest" firmware.
OMB
Mountain Man
relies on velcro to attach to the modem (i just use an elastic band), personally I think it's crap and finicky, have been meaning to get a Poynting one, just haven't got around to it
I did the following tests:
Cell-C SIM in E272 - picks up cell ID 40544 (2100MHz)
Cell-C SIM in E1820 with firmware 11.865.07.00.618 - picks up cell ID 40541 (900MHz)
Cell-C SIM in E1820 with firmware 11.865.07.00.618 forced to 2100MHz Only - nothing
Vodacom SIM in E1820 with firmware 11.865.07.00.618 forced to 2100MHz Only - picks up cell IDs 64351 and 64356 (2100MHz)
MTN SIM in E1820 with firmware 11.865.07.00.618 forced to 2100MHz Only - picks up cell IDs 5658 and 65280 (2100MHz)
Maybe something on Cell-C's network is preventing this firmware from registering?
Jola
Honorary Master
BTW, is there no compiled program or spreadsheet out there that will calculate the firmware flash code ?
Jola
Honorary Master
Thanks, I see that it does not list the E1820, but I assume that it does work ?
Mr. LOL, you are wrong. Some yes, some not. Wikipedia (before splitting MIMO into three different categories which you seem to not understand)says:
Clearly, there are two components, diversity on one side and higher spectral efficiency on the other. MIMO HSPA+ R7 which double maximum data throuput to the max 28Mbps is the other one. Both data streams must be decoded with low SNR, to be successful. It is not receive diversity. In any receive diversity scheme when one channel fades, data can be taken from the other one.
Double checked, there is no restriction to the placement of transmitting antennas. There are, due to the technical requirements in some MIMO categories, but not by definition. Dual cell reception is a very much a MIMO by definition and this category is also receive diversity.
So, just in case I am wrong, I repeat my question:
Why MIMO capable firmware works and MIMO-less firmware do not?
Complicated and obscured. It is another example of your understanding of MIMO. The clue is that the main antenna is the only one which transmits signal. You cannot even register to the tower if the tower cannot hear you. So please do not talk about switching over and MIMO, it is rubbish. With inductive coupler you are coupling your transmision to the external antenna. But I wrote about it, you don't learn.
Yes, worked for my E1820.
Jola
Honorary Master
Thanks, would prefer to have a backstop !
UnUnOctium
Expert Member
I believe what you're talking about is a hard-decision MIMO detector. Whether the E1820 uses a hard-decision detector (what you suggest) or an STBC (what I suggested but you don't seem to pick that up) only Huawei knows. It's probably in an HSPA Release specification somewhere but I don't have the time to dig through it.
P.S. Have a look at: http://www.wirelesscommunication.nl/reference/pdfandps/Slides_MIMO_course_TimSchenk_08june2007.pdf
Excuse me for using wikipedia but I don't feel like copying research papers and textbooks (granted because I'm not allowed with the papers anyways else I'd be in big trouble with the IEEE and the university):
"Dual Cell (DC-)HSDPA is the natural evolution of HSPA by means of carrier aggregation in the downlink" ... "UMTS licenses are often issued as 10 or 15 MHz paired spectrum allocations. The basic idea of the multicarrier feature is to achieve better resource utilization and spectrum efficiency by means of joint resource allocation and load balancing across the downlink carriers."
"An advanced HSPA network can theoretically support up to 28 Mbit/s and 42 Mbit/s with a single 5 MHz carrier for Rel7 (MIMO with 16QAM) and Rel8 (64-QAM + MIMO), in good channel condition with low correlation between transmit antennas." {<- MIMO, i.e. we use the same band with multiple antennae from the same BTS. In case you're curious, the low correlation is required for orthogonality between the streams} ... "An alternative method to double the data rates is to double the bandwidth, i.e. 10 MHz by using DC-HSDPA" {<- dual cell, receive from two base-stations at the same time, pretty self explanatory}.
"New HSDPA UE categories 21-24 have been introduced that support DC-HSDPA. DC-HSDPA can support up to 42Mbit/s, but unlike HSPA, it does not need to rely on MIMO transmission". ...
Please elaborate in detail what you're trying to say here. Are you implying that the primary (onboard) antenna is disabled when an external is connected or that it becomes a receive-only antenna?
Let me get this right for the inductive coupler: you're saying that if I have a modem, I connect an external to it through the connector to antenna A and then I put on an inductive coupler which connects to antenna B, I'll be (mostly) coupling to antenna A and not the primary/PCB antenna? If this is what you're saying, I'm done here.
Very interesting experience, I wish I could add some testing on my site.
Edit: is any difference in negotiated QoS in 900MHz band of E1820?
I suspect not a network problem, but modem. If original firmware can register to CellC 2100MHz in your location, then it is probably a case that Cell C black dongle do not support receive diversity on 2100MHz (only 900MHz), which is required for any MIMO. Mimo firmware for E182E asumes it deals with receive diversity hardware, tries to negotiate with BTS suitable MIMO scheme at front, but secondary cell is deaf, negotiation never finalise.
Edit: is any difference in negotiated QoS in 900MHz band of E1820?
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Previously you refered dual-cell operation to the ginggs MIMO firmware testing, which is not R8 device (not even R7 compliant). I have no problem with it.
The original text don't use term dual-cell, but you do. You apply the same term to R8 dual carrier (hence DC-HSPA) and I have problem with it because it suggests different CellIDs. Plus, your comment to DC-HSPA operation is completely inappropriate, see below. Better give up on your research papers and use Wikipedia. <G>
DC-HSPA R8 is not transmitted from two base-stations as you claim. Not at all. It is transmitted from the same antenna on adjacent carriers and reason for this is very practical. You don't need two separate 5MHz equalizers on UE, you can use single 10MHz equalizer for both data streams. It will also nicely integrate with LTE on hybrid devices.
None of above. It works as it worked before (no changes).
In proper design the main (onboard) antenna is disabled when you connect external antenna (you should perhaps know about impedance matching requirements). There is a switch inside the CRC9 socket which disconnects the main antenna from duplexer (transmitter and receivers side). This way external antenna becomes the main antenna. Similar to the miniHiFi, where internal speakers are disabled when you plug headphones jack.
Now about reasoning behind E1820 design. Frequenly above switch becomes faulty when connector is abused. There are some people on this forum who still claim (despite warnings) that they use a bare piece of wire as an antenna. The switch is not designed for such treatment and can get stuck open permanently, modem reports no signal and customer receives a new modem. A smart ass @Huawei decided to reduce warranty returns by routing external antenna connector to the diversity receivers and internal diversity antenna. In this scenario if a switch is stuck open, it will permanently disconnect internal diversity antenna from receivers, but it will only affect receive diversity operation.
In summary I am saying that when you plug external antenna to E1820, it will replace internal diversity antenna (receiving-only). The main internal antenna is not affected, however it is the only one transmitting signal and reporting RSSI.
I don't understand. Inductive coupler will couple anything in close proximity, including PCB noise. Welcome to primary school. You shouldn't really ask such a question.
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Ginggs how are you going about forcing 2100 only?
Code:
mdma.exe /hwband:400380http://mybroadband.co.za/vb/showthread.php/303489?p=5408637#post5408637
Ok thankyou - here's what i'm finding from this side with .865 firmware - over here its showing it works on 2100
900Mhz only - RSSI = -55dBm - tower id 30293 -
2100Mhz only - RSSI = -83dBm - tower id 35894
900Mhz only - RSSI = -55dBm - tower id 30293 -
2100Mhz only - RSSI = -83dBm - tower id 35894
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Excellent! So it appears the firmware is good, the problem 1geoff99 and I had could just be local to our base stations or local to Cape Town.
I've had some strange things happen, like when I first tried a Vodafone K4605 modem on Cell-C, it would connect on 2G, but not on 3G, and then there was a week where I could receive calls on UMTS900, but not on UMTS2100, both of which were resolved without me having to change anything. It wouldn't surprise me if Cell-C were getting logs of these kind of problems from the base stations and pro-actively fixing them.
Do you have an external antenna on the E1820? How is it attached, pigtail or inductive coupler?So either the E1820 is a rubbish modem or Cell C fixed something
I noticed you tested against two different speed test servers, can you repeat the test selecting the same server each time to eliminate the possibility that there's something wrong with the Johannesburg server?