TRP vs. EIRP and interference between mobile networks

Transcription

1 Security Level: TRP vs. EIRP and interference between mobile networks 6 June For discussion HUAWEI TECHNOLOGIES CO., LTD.

2 Contents Introduction Antenna array gain pattern EIRP vs. TRP Conclusions HUAWEI TECHNOLOGIES 2/24

3 Introduction Here we discuss the merits of Equivalent Isotropic Radiated Power (EIRP) and Total Radiated Power (TRP) in the context of specifying base station (BS) adjacent channel leakage ratio (ACLR) and out-of-block emission limits in relation to interference between mobile networks. The discussions are particularly relevant to BSs which perform beamforming via large numbers of antenna elements. HUAWEI TECHNOLOGIES 3/24

4 Contents Introduction Antenna array gain pattern EIRP vs. TRP Conclusions HUAWEI TECHNOLOGIES 4/24

5 Array geometry z (N V 1)d V (n 1)d V 2d V d V d H 2d H (m 1)d H (N H 1)d H y x HUAWEI TECHNOLOGIES 5/24

6 Contributions to radiated signal z cos( ) sin( )sin( ) y x HUAWEI TECHNOLOGIES 6/24

7 Antenna element pattern A E (, ) = V E (, ) 2 Typical values: G = 8 dbi, SLA V = A m = 30 db. HUAWEI TECHNOLOGIES 7/24

8 Antenna array gain (1/2) Radiated signal: Array response coefficients: Beamforming weights (normalised): Rewriting, we have: HUAWEI TECHNOLOGIES 8/24

9 Antenna array gain (2/2) Antenna array power gain: Signal correlation matrix: Algebraic manipulation: Rewriting, we have: HUAWEI TECHNOLOGIES 9/24

10 Summary Numbers of antennas Array response Radiated power Conducted power Element pattern Correlation Beamforming weights P Tx : : P(, ) Antenna array G(, ) HUAWEI TECHNOLOGIES 10/24

11 Contents Introduction Antenna array gain pattern EIRP vs. TRP Conclusions HUAWEI TECHNOLOGIES 11/24

12 Wanted vs. unwanted signals u 1 (t) û 1 (t) s(t) Frequency + BB RF Frequency Unwanted emissions generated in distinct transmitter chains due to noise/non-linearity : : u 0 (t) BB RF u N (t) û N (t) The correlation of out-of-block emissions across the antenna elements is uncertain. Frequency HUAWEI TECHNOLOGIES 12/24

13 1) Array gain and signal correlation N V = 10, N H = 1, d = 0.9. Maximum array gain: 8+10log(N) = 18 db =1.0 Maximum element gain: 8 dbi =0.0 =0.0 =0.2 =0.4 =0.6 =0.8 =1.0 HUAWEI TECHNOLOGIES 13/24

14 1) Radiate power P Tx = 46 dbm, N V = 10, N H = 1, d = 0.9, ACLR = 45 db. Maximum EIRP: P TX +18=46+18=64 dbm ACLR=45 Wanted signal P Tx + G(, ) =1.0 Wanted signal TRP = 46 dbm Unwanted signal TRP = 1 dbm (for all ) Unwanted signal (P Tx ACLR) + G(, ) =0.0 =0.2 =0.4 =0.6 =0.8 =1.0 HUAWEI TECHNOLOGIES 14/24

15 1) Setting out-of-block limits P Tx = 46 dbm, N V = 10, N H = 1, d = 0.9, ACLR = 45 db. [ =1 ] EIRP IB EIRP OOB = 45 db TRP IB TRP OOB = 45 db Specifying ACLR w.r.t EIRP or TRP is equivalent. [ =0 ] If ACLR is specified w.r.t EIRP rather than TRP, then this will result in an uncertainty of 10 db in total unwanted emissions. HUAWEI TECHNOLOGIES 15/24

16 2) Array gain and signal correlation N V = 16, N H = 8, d = 0.6. Maximum array gain: 8+10log(N) = 29 db =1.0 Maximum element gain: 8 dbi =0.0 =0.0 =0.2 =0.4 =0.6 =0.8 =1.0 HUAWEI TECHNOLOGIES 16/24

17 2) Radiate power P Tx = 46 dbm, N V = 16, N H = 8, d = 0.6, ACLR = 45 db. Maximum EIRP: P TX +G max =46+29=75 dbm ACLR=45 Wanted signal P Tx + G(, ) =1.0 Wanted signal TRP = 46 dbm Unwanted signal TRP = 1 dbm (for all ) Unwanted signal (P Tx ACLR) + G(, ) =0.0 =0.2 =0.4 =0.6 =0.8 =1.0 HUAWEI TECHNOLOGIES 17/24

18 2) Setting out-of-block limits P Tx = 46 dbm, N V = 16, N H = 8, d = 0.6, ACLR = 45 db. [ =1 ] EIRP IB EIRP OOB = 45 db TRP IB TRP OOB = 45 db Specifying ACLR w.r.t EIRP or TRP is equivalent. [ =0 ] If ACLR is specified w.r.t EIRP rather than TRP, then this will result in an uncertainty of 21 db in total unwanted emissions. HUAWEI TECHNOLOGIES 18/24

19 Multi-cell system level simulations Source: R (Huawei) Impact on downlink throughput is insensitive to the correlation of unwanted out-of-block signal across antenna elements. Mean loss in downlink throughput mobile network a result of interference from an adjacent channel mobile network which uses AAS base stations ACLR is specified based on TRP UE ACS = 33 db, hence the flattening. HUAWEI TECHNOLOGIES 19/24

20 Multi-cell system level simulations Source: R (Ericsson) If ACLR is specified based on EIRP, then interference is greater, and downlink throughput of the victim network degrades considerably. Loss in mean downlink throughput mobile network a result of interference from an adjacent channel mobile network which uses AAS base stations = 0 Unwanted signal is uncorrelated across antennas. HUAWEI TECHNOLOGIES 20/24

21 Multi-cell system level simulations Source: R (Huawei) Impact on downlink throughput is insensitive to the correlation of unwanted out-of-block signal across antenna elements. 95 th percentile Loss in downlink throughput mobile network a result of interference from an adjacent channel mobile network which uses AAS base stations ACLR is specified based on TRP UE ACS = 33 db, hence the flattening. HUAWEI TECHNOLOGIES 21/24

22 Absolute unwanted emissions limits Absolute levels of unwanted emissions will also depend on the extent of correlation between different transmitters. This means that the absolute EIRP of unwanted emissions also varies among different BSs, whereas TRP does not. The 3GPP simulations demonstrate that the impact on adjacent channel systems depends on the total power of radiated interference, and not the spatial pattern of the interference. This is logical because a wider spatial pattern of interference will impact a larger number of users, but to a lower extent, compared to a narrow pattern of emissions with increased EIRP. Therefore, it is the TRP and not EIRP of absolute emissions that directly relates to the degradation in the performance of other adjacent channel systems. Note that even if emissions were fully correlated between transmitters, such that the beam shape would be the same for wanted and unwanted emissions, it would still be the TRP of the emissions that would relate to the impact on other systems. HUAWEI TECHNOLOGIES 22/24

23 Contents Introduction Antenna array gain pattern EIRP vs. TRP Conclusions HUAWEI TECHNOLOGIES 23/24

24 Conclusions The correlation of the out-of-block emissions across the transmit antennas of a mobile network base station is uncertain. If the out-of-block emissions of a base station (BS) are fully correlated across its transmit antennas, then EIRP and TRP are equivalent for specifying the BS s ACLR and out-of-block emission limits. Otherwise, specifying the BS ACLR and out-of-block emission limits based on EIRP (rather than TRP) implies an uncertain level of total unwanted emissions. Importantly, when the BS ACLR and out-of-block limits are specified based on TRP, the impact of interference on the throughout of an adjacent channel mobile network is broadly insensitive to the correlation of the out-of-block emissions across the BS s transmit antennas. Even if unwanted emissions were fully correlated across transmitters, and had the same beam pattern as wanted emissions, it would still be the TRP that would define the impact on the performance of adjacent channel systems. Conclusion: TRP is the appropriate metric for specifying the ACLR and out-of-block emission limits, in the context of interference between adjacent channel mobile networks. HUAWEI TECHNOLOGIES 24/24

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