Scenario card: urban-grid-28ghz-beams

Small cells with SSB beams and beam failure recovery in the TR 37.885 urban grid at 28 GHz (FR2)
Available since version 1.10.0. Use it as scenario: urban-grid-28ghz-beams in a configuration file or hl.builtin_scenario("urban-grid-28ghz-beams") in Python.

Purpose

The urban-grid-10ghz world moved to 28 GHz (FR2-1) with explicit SSB beams instead of the antenna abstraction: every site carries three sectors (cells), each a 4 x 8 panel with the element of TR 38.901 Table 7.3-1 sending 8 SSB beams. The serving beam follows periodic L1-RSRP beam reports; beam failure detection, candidate beam detection and the L1-RSRP measurements use the FR2 evaluation periods of TS 38.133 (receive-beam sweeping factor N = 8), and a detected beam failure is recovered by random access or ends in a radio-link failure (random-access problem). Use it to study beam management and its interplay with handover at FR2.

Layout

Layout of urban-grid-28ghz-beams

Three by three blocks (433 m x 250 m between street centre lines, 20 m streets), 76 sites with three sectors each (228 cells).

Parameters

Values in bold differ from the HandoverLab defaults.

Key Value Source
layout.kind street_grid TR 37.885 Annex A (urban grid)
layout.blocks [3, 3] TR 37.885 Table A-1 (minimum 3 x 3 blocks)
layout.pitch_m [433, 250] TR 37.885 Annex A (433 m x 250 m)
layout.street_width_m 20 TR 37.885 Annex A (20 m)
layout.site_spacing_m 100 assumption (dense small cells along the streets; TR 37.885 Table 6.1.3-2 has 500 m macro sites in the urban grid)
layout.site_offset_m 9 assumption (sites on the pavement)
layout.sites none regular placement along the streets
radio.carrier_ghz 28 FR2-1 (24.25-52.6 GHz, TS 38.104 Table 5.1-1); 28 GHz is an assumption
radio.bandwidth_mhz 400 assumption (400 MHz FR2 channel at 120 kHz subcarrier spacing)
radio.tx_power_dbm 35 assumption (small cell; TR 37.885 Table 6.1.1-2 has 43 dBm for its macro sites)
radio.ue_gain_db 0 assumption
radio.noise_figure_db 10 ITU-R M.2412-0 Table 5b (UE noise figure at 30 GHz: 10 dB, high-performance UE)
radio.bs_height_m 10 TR 38.901 Table 7.4.1-1 (UMi: 10 m)
radio.ue_height_m 1.6 TR 37.885 clause 6.1.2 (urban option A: 100 % vehicle type 2, antenna height 1.6 m; since 2.1.0, until 2.0.0 1.5 m)
radio.pathloss umi_street_canyon TR 38.901 Table 7.4.1-1
radio.shadow_los_db 4 TR 38.901 Table 7.4.1-1 (UMi and UMa LOS: 4 dB)
radio.shadow_nlos_db 7.82 TR 38.901 Table 7.4.1-1 (UMi NLOS: 7.82 dB)
radio.shadow_decorr_m 10 TR 38.901 Table 7.5-6 Part-1 (UMi: 10 m LOS, 13 m NLOS; the LOS value is used for both, see the limitations)
radio.shadow_site_corr none unset: uncorrelated between sites, TR 38.901 clause 7.5 step 4 (radio.channel_detail simple: 0.5)
radio.place_share 1 assumption (blockage tied to place)
radio.clutter_los true TR 38.901 clause 7.6.3.3 (spatially consistent LOS state), applied on top of the building geometry
radio.los_corr_m 50 TR 38.901 Table 7.6.3.1-2 (LOS/NLOS state, UMi and UMa: 50 m)
radio.time_var_db 1.5 assumption (moving blockers)
radio.time_var_tau_s 1 assumption
radio.l1_error_db 1 assumption (error of one L1 RSRP sample)
radio.penetration_db 0 off by default; TR 38.901 clause 7.4.3.2: 9 dB in a standard car
radio.penetration_sd_db 0 off by default; TR 38.901 clause 7.4.3.2: 5 dB in a standard car
radio.energy_p0_w 56 EARTH model, micro base station (Auer et al. 2011, Table 2): 56 W
radio.energy_slope 2.6 EARTH model, micro base station (Auer et al. 2011, Table 2): 2.6
radio.map_res_m 1 numerical setting
radio.scs_khz 120 unset: 30 kHz up to 7.125 GHz, 120 kHz above (assumption)
radio.beams.sectors 3 default of the beam model (user guide)
radio.beams.sector_az0_deg 30 default of the beam model (user guide)
radio.beams.n_ssb 8 default of the beam model (user guide)
radio.beams.panel [4, 8] default of the beam model (user guide)
radio.beams.tilt_deg 100 default of the beam model (user guide)
radio.beams.beam_span_deg none default of the beam model (user guide)
radio.beams.ssb_avg none default of the beam model (user guide)
radio.beams.ssb_thresh_dbm none default of the beam model (user guide)
radio.beams.report_s 0.04 default of the beam model (user guide)
radio.beams.switch_db 2 default of the beam model (user guide)
radio.beams.tci_delay_s 0.01 default of the beam model (user guide)
radio.beams.rx_sweep_n none default of the beam model (user guide)
radio.beams.bfd true default of the beam model (user guide)
radio.beams.bfi_max 3 default of the beam model (user guide)
radio.beams.bfd_timer 4 default of the beam model (user guide)
radio.beams.bfr_timer_s 0.1 default of the beam model (user guide)
radio.beams.rsrp_thresh_ssb_dbm -115 default of the beam model (user guide)
radio.beams.ra_attempt_s 0.01 default of the beam model (user guide)
radio.beams.preamble_max 10 default of the beam model (user guide)
radio.beams.rlm_rs tci default of the beam model (user guide)
protocol.step_s 0.01 numerical setting
protocol.l1_period_s 0.04 assumption (L1 sample period)
protocol.l3_k 4 TS 38.331 clause 5.5.3.2
protocol.label_period_s 0.2 numerical setting
protocol.report_interval_s 0.12 TS 38.331 reportInterval (ms120)
protocol.qout_db -8 TR 36.839 (Qout -8 dB)
protocol.qin_db -6 TR 36.839 (Qin -6 dB)
protocol.qout_window_s 0.2 TS 38.133 (evaluation period, 200 ms)
protocol.qin_window_s 0.1 TS 38.133 (evaluation period, 100 ms)
protocol.n310 1 TR 36.839
protocol.n311 1 TR 36.839
protocol.t310_s 1 TR 36.839 (1 s)
protocol.prep_s 0.05 TR 36.839 (50 ms)
protocol.exec_s 0.04 TR 36.839 (40 ms)
protocol.reest_s 1 assumption (1 s outage); TS 38.133 6.2.1.2.1 bounds the delay by 50 ms + cell identification (FR1: 200 ms known, 800 ms unknown cell, Table 6.2.1.2.1-1) + system information + PRACH; TR 36.842 Table E.1-2 uses 250 ms
protocol.cho_recovery_s 0.4 TS 38.300 clauses 9.2.3.1 and 9.2.7 (recovery into a CHO candidate; assumption 0.4 s)
protocol.pingpong_s 1 TR 36.839 (minimum time of stay, 1 s)
protocol.cfg_loss_as_failure false check mode only
protocol.lm_load none off by default: link monitoring sees the load of the data channel (calibration option)
protocol.lm_load_per_ue 0 off by default (calibration option)
protocol.exec_can_fail true TR 36.839: the execution fails when the target is below Qout
protocol.rlm_holdoff_s 0.2 0.2 s since 2.0.0: an interpretation of TS 38.133 8.1.2.2 (evaluation over the last T_Evaluate_out, 200 ms in FR1) on a newly joined cell
protocol.rlm_eval ts38133 TS 38.133 Tables 8.1.2.2-1/-2 (FR2: N = 8)
traffic.services 5 entries TS 23.501 Table 5.7.4-1 (5QI); thresholds are assumptions
traffic.se_max 7.4 assumption (spectral-efficiency cap)
traffic.hotspot_share 0.25 assumption
traffic.hotspot_load [0.55, 0.85] assumption
traffic.normal_load [0.05, 0.25] assumption
traffic.load_tau_s 0.2 assumption
traffic.rate_scale 1 assumption
traffic.label_load 1 assumption (all cells transmit for the label)
traffic.model fixed fixed: constant service rates (the model of 1.0)
traffic.period_s 0.02 periodic model: 20 ms, as VoIP
traffic.packet_bytes 100 periodic model: assumption
traffic.ftp_file_bytes 500000 FTP model 3 (TR 36.872 Annex A.1) with 0.5 Mbyte files (TR 38.802 Table A.2.1-1; TR 38.821 Table 6.1.1.1-7)
traffic.ftp_rate_hz 0.1 ftp3 model: assumption (file arrival rate per user)
mobility.users 40 assumption
mobility.profile v60 TR 37.885 clause 6.1.2 (urban option A: 60 km/h in all lanes) and Table A-1 (2 lanes of 3.5 m per direction): profile v60 (since 2.0.0)
mobility.groups none profile
run.duration_s 120 numerical setting
run.warmup_s 20 numerical setting

Not read by this layout and radio model, so not listed: radio.bs_gain_db, radio.isolation.

Known limitations

  • No fast fading and no UE beamforming (the UE's receive-beam sweeping enters only through the factor N of TS 38.133).
  • Evaluation periods are modelled as exponential averages whose time constant is the TS 38.133 period, a conservative reading of minimum requirements.
  • Changed in 1.11.0: until 1.10.0 the UE noise figure was 7 dB (the default), below the 10 dB of ITU-R M.2412-0 at 30 GHz.
  • Small cells on UMi along the streets, as in urban-grid-10ghz: TR 37.885 itself has 500 m macro sites with UMa in the urban grid (Tables 6.1.3-2 and 6.2.1-2).
  • The failure model is not calibrated in absolute terms; read failure rates relative to each other.
  • The LOS state of a link is LOS only if the buildings leave it clear and the spatially consistent LOS variable of TR 38.901 clause 7.6.3.3 is below the LOS probability of Table 7.4.2-1; the share of LOS links is therefore lower than Table 7.4.2-1 gives (which handoverlab verify compares only for the links clear of buildings).
  • One shadowing decorrelation distance, the UMi LOS value of 10 m, also for the NLOS links (TR 38.901 Table 7.5-6 Part-1: UMi LOS 10 m, NLOS 13 m); LOS and NLOS links share one unit shadowing realisation scaled by the LOS or NLOS standard deviation, so the shadowing keeps its sign when a link changes state (TR 38.901 gives separate LOS and NLOS parameters, Table 7.5-6).
  • A vehicle keeps a lane offset drawn at the start, on either side of the street centre line, through turns: it may drive in a lane of the opposite direction (TR 37.885 Table A-1 has 2 lanes in each direction).
  • The number of vehicles is set for run time: TR 37.885 clause 6.1.2 places vehicles with a gap of max(2 m, exponential with mean speed x 2 s), which gives hundreds of vehicles in the grid; the interference load of HandoverLab does not depend on the number of users.
  • 228 cells with 8 beams each: a run takes several times longer than urban-grid-10ghz.

Reference results

  • The beam and requirement formulas are checked against hand values in handoverlab verify (group extended).