Thanks Thanks:  7
Page 2 of 3 FirstFirst 123 LastLast
Showing results 11 to 20 of 23

Thread: LTE MIMO : RANK, LAYERS and Antenna ports

  1. #11
    Member Reputation: 108
    Join Date
    2015-01-07
    Posts
    136


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Quote Originally Posted by techfolkcmr View Post
    We have UMTS network with single carrier of 5MHZ. My doubt is can MIMO(2*2) be enabled/implemented without second carrier or MIMO is the final option after availing second or third carriers and what will be the maximum achievable throughput if MIMO can be implemented with single carrier.
    Enabling MIMO in UMTS will not give you much gain, as due to the coding/modulation scheme of UMTS, it is not very suitable for MIMO use. If you need to decide between MIMO or another carrier, I would suggest add a second carrier to your system. The fact the 2x2 MIMO theoretical maximum is 28Mbits, and the non-MIMO is 21.6 on UMTS it already gives you an impression of how little gain it will have.

  2. Thanks techfolkcmr thanked for this post
  3. #12
    Senior Member Reputation: 608
    Join Date
    2010-10-08
    Posts
    443


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Quote Originally Posted by subway View Post
    Enabling MIMO in UMTS will not give you much gain, as due to the coding/modulation scheme of UMTS, it is not very suitable for MIMO use. If you need to decide between MIMO or another carrier, I would suggest add a second carrier to your system. The fact the 2x2 MIMO theoretical maximum is 28Mbits, and the non-MIMO is 21.6 on UMTS it already gives you an impression of how little gain it will have.
    many thanks for your direct answer. One more scenario if the same 5MHZ of UMTS2100 is used for LTE what will be the theoretical throughput and practical throughout for a user.
    Please add reputation by clicking * at left bottom of post & Hit Thanks and report Helpful by clicking Thumps Up if you like my post . Knowledge is Power & Sharing is Caring.

  4. #13
    Senior Member Reputation: 591
    Join Date
    2010-05-10
    Posts
    343


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    A rough back of the envelope estimate will yield a theoretical gross speed of 25 Mbps for 5MHz (approx 1Mbps per RB, considering no protection, 64QAM). If you add MIMO (m,n) to it then the SINR will determine the throughput gains from MIMO. Capacity = min (m,n) B log2 (1 + SINR)

  5. Thanks techfolkcmr thanked for this post
  6. #14
    Member Reputation: 108
    Join Date
    2015-01-07
    Posts
    136


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Quote Originally Posted by techfolkcmr View Post
    many thanks for your direct answer. One more scenario if the same 5MHZ of UMTS2100 is used for LTE what will be the theoretical throughput and practical throughout for a user.
    Compared to UMTS, you will get higher speeds, despite the fact you use the same amount of bandwidth, due to the fact that:

    - 2x2 MIMO is mandatory on LTE (for the DL), so either as transmit diversity or as space multiplexing, your clients will benefit
    - frequency based scheduling (not possible in UMTS due to the single carrier nature of the modulation)
    - faster TTI
    - on the uplink you can introduce 64QAM and/or Rx diversity to extend your uplink coverage
    - HARQ improved a lot (faster, more instances, more adaptive)

    Based on the LTE capable UE penetration, I would definitely introduce 5MHz LTE instead of 5MHz UMTS. But you will need to consider if there is no VoLTE, your voice capacity will not be expanded by this (SRVCC/CSFB will still apply).

  7. Thanks techfolkcmr thanked for this post
  8. #15
    Senior Member Reputation: 608
    Join Date
    2010-10-08
    Posts
    443


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Quote Originally Posted by subway View Post
    Compared to UMTS, you will get higher speeds, despite the fact you use the same amount of bandwidth, due to the fact that:

    - 2x2 MIMO is mandatory on LTE (for the DL), so either as transmit diversity or as space multiplexing, your clients will benefit
    - frequency based scheduling (not possible in UMTS due to the single carrier nature of the modulation)
    - faster TTI
    - on the uplink you can introduce 64QAM and/or Rx diversity to extend your uplink coverage
    - HARQ improved a lot (faster, more instances, more adaptive)

    Based on the LTE capable UE penetration, I would definitely introduce 5MHz LTE instead of 5MHz UMTS. But you will need to consider if there is no VoLTE, your voice capacity will not be expanded by this (SRVCC/CSFB will still apply).
    Are you sure MIMO mandatory. Because part of our network changed to LTE with same architecture of UMTS on radio side (i.e) SISO only
    Please add reputation by clicking * at left bottom of post & Hit Thanks and report Helpful by clicking Thumps Up if you like my post . Knowledge is Power & Sharing is Caring.

  9. #16
    Member Reputation: 453
    Join Date
    2009-12-31
    Posts
    251


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    It is mandatory from 3gpp specs point of view, meaning that MIMO has to be technically supported.

    If operator wants to have SISO then its different story. MIMO feature can always be deactivated or otherwise no need to purchase the feature if its not needed.

  10. Thanks techfolkcmr thanked for this post
  11. #17
    Senior Member Reputation: 608
    Join Date
    2010-10-08
    Posts
    443


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Quote Originally Posted by DJ Download View Post
    It is mandatory from 3gpp specs point of view, meaning that MIMO has to be technically supported.

    If operator wants to have SISO then its different story. MIMO feature can always be deactivated or otherwise no need to purchase the feature if its not needed.
    Yup we are using SISO Only.The maximum throughput difference between UMTS-5MHZ SISO 64QAM (DL theoretically 21.4 Mbps) and LTE-5MHZ SISO (DL theoretically 25 Mbps) is very less and Pls justify (Just like an operator) why shifting to LTE is necessary with the same 2100 band and 5MHZ bandwidth of UMTS.
    Last edited by techfolkcmr; 2018-12-30 at 02:54 AM
    Please add reputation by clicking * at left bottom of post & Hit Thanks and report Helpful by clicking Thumps Up if you like my post . Knowledge is Power & Sharing is Caring.

  12. #18
    Senior Member Reputation: 591
    Join Date
    2010-05-10
    Posts
    343


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    3GPP specs are not mandatory for the operator. It is left to the operator's volition. It can be said that only regulations are mandatory.

  13. #19
    Member Reputation: 108
    Join Date
    2015-01-07
    Posts
    136


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Quote Originally Posted by techfolkcmr View Post
    Are you sure MIMO mandatory. Because part of our network changed to LTE with same architecture of UMTS on radio side (i.e) SISO only
    As it is already said, it is mandatory for the vendors (network element and UE manufacturers). So all UEs and enodeb will support it. Of coarse there can be special circumstances when you cannot use MIMO (you can, but not practical): like in an indoor DAS, or leaky feeder installation. Other than that, even the older 2100MHz RRUs are two chain units, and the old sector antennas are also having at least two chains. So given the fact LTE is capable to exploit this and present meaningful gains, why not to use it? Especially if the spectrum is limited (5MHz).

  14. #20
    Member Reputation: 453
    Join Date
    2009-12-31
    Posts
    251


    Default Re: LTE MIMO : RANK, LAYERS and Antenna ports

    Hi,

    I think the advantage of LTE over UMTS is not knly from data rate perspective ( although im not sure of UMTS suppory 256 QAM like LTE).

    Basically OFDM technique that is used in LTE is better compared to WCDMA. SC-FDMA in the UL direction is also better than WCDMA.

    UL in LTE is also orthogonal, meaning you dont have to worry about intra cell UL interference increase due to high load in the cell. I think LTE is also better in handling user capacity compared to UMTS.

    Another advantage is also no RNC is needed so you get rid of a point of failure in a region and you dont need to invest in the hardware, software license for RNC (incl. license for extra capacity). Next to that you also save maintenance / resource cost to take care of RNC.

    Security in LTE is also better as there is option to use IPSec.


    /DJ D

    Quote Originally Posted by techfolkcmr View Post
    Yup we are using SISO Only.The maximum throughput difference between UMTS-5MHZ SISO 64QAM (DL theoretically 21.4 Mbps) and LTE-5MHZ SISO (DL theoretically 25 Mbps) is very less and Pls justify (Just like an operator) why shifting to LTE is necessary with the same 2100 band and 5MHZ bandwidth of UMTS.

  15. Thanks techfolkcmr thanked for this post

Bookmarks

Bookmarks

Posting Rules

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •