Talk:Spectral efficiency

message: I propose that the article add 5G-NR to the table.  — Preceding unsigned comment added by 2600:1700:8750:6530:8560:8295:8FFF:98C (talk) 18:55, 21 January 2023 (UTC)
thread_title: Add 5G-NR to table

message: I added D-AMPS to comparison table. some notes:
* D-AMPS (formal standards IS-54 and later IS-136) is actually 6 time slots, not 3 slots. but in real world installations 2 slots were always paired to achieve 13kbps, since 6.5kbps vocoders were not good enough at the time. so i wrote 13kbps * 3 slots in the table.
* technically, 13kbps is the data rate used for voice. for data transmission, the theoretical maximum data rate is 16kbps. since it was rarely achieved in practice, i kept the widely-known 13kbps figure.
* mentioned 1/7 reuse factor comes from the common hexagonal tile configuration. this is widely known fact - you'll find a hexagonal tile diagram & explanation in virtually any book about cellular communications.
* common literature mentions reuse factor of 1/4 or 1/5 when using sector antennas, but this is true for most other communication systems and not just D-AMPS. i kept with the conservative 1/7 reuse factor here, so that we'll have a apples-to-apples comparison with other standards. keep in mind that if you change reuse factors in other standards, you might want to change the factor for D-AMPS. it all depends on the antenna configurations...  —Preceding unsigned comment added by 85.250.43.101 (talk) 16:21, 10 May 2008 (UTC)
thread_title: added D-AMPS to table

message: The definition could be a bit more general as it applies to more than digital.  It could apply to analogue.  It could apply to how spectrum is allocated by regulatory agencies.
: What units of measurement do you have in mind? I mentioned system spectral efficiency in Erlangs/MHz/cell in the article, which also can be applied to analogue. Mange01 (talk) 22:16, 21 February 2008 (UTC)
replies: text: correction: channel is quantized (on both sides) at 13 to 14 bits, and then u-law or a-law companded to 8 bits. 89.138.246.240 (talk) 00:12, 16 February 2008 (UTC)
replies: text: I somewhat doubt that the baseband waveform used for digital modulation undergoes A/mu-law companding.  Oli Filth(talk) 02:02, 16 February 2008 (UTC)
replies: text: The modem compensates for the A/mu-law companding, meaning that it expands the 8 bit signal to a 13 bit signal before it sends it. So the modem can only use 8 bits per sample. (In Europe. Is it 7 or 8 bit in the U.S.?)Mange01 (talk) 22:16, 21 February 2008 (UTC)

text: Wouldn't that be the same as the article radio resource management? Mange01 (talk) 22:16, 21 February 2008 (UTC)

text: Mehwoot was being an idiot and just changing random numbers, I'm pretty sure.  It was probably correct the way it was.58.106.7.5 12:35, 27 April 2007 (UTC)
thread_title: Review

message: Please vote at Talk:Eb/N0#Survey on which unit that should be used at Wikipedia for measuring  Spectral efficiency. For a background discussion, see Talk:Spectral_efficiency#Bit/s/Hz and Talk:Eb/N0#Bit/s/Hz.
Mange01 (talk) 07:21, 16 April 2008 (UTC)
thread_title:  Survey: bit/s/Hz, (bit/s)/Hz or bit·s<sup>−1</sup>·Hz<sup>−1</sup> as [[Spectral efficiency]] unit? 

message: There was a very nasty picture that made my stomach sick when I opened this page, but it vanished before I could do anything. Did any good soul remove it, or we have a hole in Wikipedia?
There was no image link in page source. Probably reverted between the time I downloaded vandalized version and the time it was fixed. There are some very ill people out there. You have my continuing support in fighting them.
P.S.
Anyone thought of AI software that would try to establish whether the image submitted is something vulgar and notify administrators? I have a few clues to start with. Thx. 
-- Mtodorov 69 13:47, 7 May 2007 (UTC)
thread_title:  Vandalized 

message: What is the spectral effiency of analog transmission modes as AM ( A3), SSB, FM, analogue TV, etc.?  —Preceding unsigned comment added by 91.46.209.184 (talk) 20:00, 15 April 2008 (UTC)
replies: text: I have found one article that seems to be measuring number of simultaneous calls per bandwidth unit in Erlang/Hz. [doi.wiley.com/10.1002/0470020121.ch7] However, I don't have access to the full text version, only the Google search result, so I might have misunderstood it. There are several articles measuring the area capacity in Erlang/MHz/area unit or Erlang/MHz/cell, as I mentioned in the System spectral efficiency section. Mange01 (talk) 18:45, 16 April 2008 (UTC)
thread_title:  Spectral effiency of analog transmission modes 

message: Not sure if this is the right place to put this but there is a misleading inconsistency in this page and the main wimax page  with regards to the spectral efficiency of wimax (802.16d), this page states an efficiency of (4.8 bit/s)/Hz but the main wimax page states for 802.16d a spectral efficiency of 3.7 (bit/s)/Hz
: Spectral efficiency for any adaptive scheme (like WiMAX or LTE) is a bit tricky to nail down, since Marketing wants to quote the maximum value while Engineering cringes and generally talks in terms of averages.  Also, many efficiency calculations depend on the exact overhead structure used, etc., so it's not at all unusual to have different authoritative sources quote figures that vary by even that much. NX7U (talk) 04:49, 10 June 2008 (UTC)
thread_title: WiMAX spectral efficiency?

message: I split the table entry for CDMA2000 1x into separate entries for voice and PD (packet data), and made some corrections to the frequency reuse and resultant calculations.  Also added a new entry for CDMA2000 1x EV-DO. NX7U (talk) 04:44, 10 June 2008 (UTC)
thread_title: Additional 3G table entries

message: I'd like to add that the definition of spectral efficiency assumed on this page is not the only one in use.  Another, older and still pretty common definition is the ratio between the capacity of the modulation method used and the Shannon capacity.  Under this definition, BPSK has more spectral efficiency than 64-QAM, since the mutual information limit for 64-QAM is so far away from capacity.  Whereas this page's definition would simply say that 64-QAM has more "efficiency" because it is sending more bits.
I think at minimum this page should specifically give a literature reference as to where the definition being used came from.  —Preceding unsigned comment added by Spope3 (talk • contribs) 22:04, 2 March 2009 (UTC)
replies: text: The existing intro states "Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the amount of information that can be transmitted over a given bandwidth in a specific communication system".  I don't think this definition contradicts what you're saying.  Oli Filth(talk|contribs) 22:09, 2 March 2009 (UTC)
replies: text: Several different definitions occur in the literature, see , but the unit is almost always "something per hertz". Otherwize it should not be called "spectral" i.m.h.o. I have searched on Google books, but i have not found your definition Spope3 in the literature. To my understanding, your definition would result in a unitless measure, for example a percentage measure. It resembles channel efficiency (missing article) or channel utilization, which is a normalized throughput, related to the maximum possible throughput. Mange01 (talk) 10:04, 3 March 2009 (UTC)
thread_title: Definition of Spectral Efficiency

message: Not sure if that is intentional, but example numbers are not consistent. Example 7 is followed by examples 6 and 7.93.159.77.200 (talk) 08:34, 16 July 2009 (UTC)
thread_title:  Example numbers 

message: Would it be a good idea to move the comparison to a template that is embedded in the end of articles about all compared systems? For example template:spectral efficiency comparison table. The table should be collapsible. 
Can it be done? Mange01 (talk) 21:08, 7 May 2010 (UTC)
thread_title:  Move the table to a template that can be embedded in many articles? 

message: We need to add one new column to the table,
with Energy per bit, from were we can compare
the different Carrier/Noise needed to each modulation.  —Preceding unsigned comment added by 85.138.250.13 (talk) 10:54, 22 October 2010 (UTC)
thread_title:  New column to the able: Energy per bit 

message: The reference to: Kolbrun Johanna Runarsdottir (2008). "Comparison of Mobile WiMAX and HSDPA" (PDF). Master of Science Thesis, Stockholm, Sweden. is a dead link now. I've tried to find it on-line, but I can't. If anyone know where to find it, please update the link.
The numbers for 3G WCDMA seems a bit strange, at least without mentioning the number of "mobiles" that can simultaneously access the system. I'd appreciate it anyone have more information about WCDMA.
Haakoo (talk) 15:27, 19 January 2011 (UTC)
replies: text: For me the values seem very low if you compare them with the other techniques. Does WCDMA realy have a spectral efficiency of only 0.077 (bit/s)/Hz? I do understand that you can have several transmission at the same time. My understanding might be wrong, but shouldn't spectral efficiency reflect the "total" amount of (bit/s)/Hz? It might also be something related to CDMA I haven't quite understood that would explain why it is like it is. Haakoo (talk) 10:50, 20 January 2011 (UTC)
replies: text: A very low value is correct for a spread-spectrum signal, and no it shouldn't reflect the total.  The overall bad usage efficiency comes from other mechanisms, not from spectral efficiency. Dicklyon (talk) 15:39, 20 January 2011 (UTC)
thread_title:  Missing reference