implementation of tm4 into oai softmodem · pmiq # of layer 2 (ri 1) 1 1 2 s s s− s 2 1 2 s s −...

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IMPLEMENTATION OF TM4 INTO OAI SOFTMODEM

Joint ETSI - OSA Workshop: Open

Implementations and

Standardization

Pre Event Training – 11 December 2018

Khodr Saaifan

[email protected]

Fraunhofer Institute for Integrated Circuits (IIS)

mailto:[email protected]

mailto:[email protected]

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Agenda

o TM4 Basics in LTE

o Review of OAI-eNB Thread and PHY Procedures

o eNB: PHY TX Procedures

o MAC: DL Scheduling

o Review of OAI-UE Thread and PHY Procedures

o UE: PHY RX Procedures

o UE Measurement Procedures

o Demo Setup and Results

o UE Statistics

o eNB Statistics

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txdataF[0][ttioffest]

1

𝑋1

2

1


1

𝑋2

2

1

𝐻𝑑𝑙𝑐ℎ 0 :𝐻11[𝑘]

𝐻𝑑𝑙𝑐ℎ[2]: 𝐻12[𝑘]

𝐻𝑑𝑙𝑐ℎ 1 : 𝐻21[𝑘]


rxdataFext[0][ttioffest]

1

𝑌1

2

1

rxdataFext[1][ttioffest]

1

𝑌2

2

1

TM4 Basics in LTE

The MIMO channel at the 𝑘th subcarrier:

𝑯 =𝐻11[𝑘] 𝐻12[𝑘]

𝐻21[𝑘] 𝐻22[𝑘]

Channel decomposition:

𝑯 = 𝑼𝜆1 00 𝜆2

𝑽𝐻

𝑿 = 𝑽𝑿 𝒀 = 𝑼𝐻𝒀

𝑋 1

𝑋 2

Modulated Symbols

𝑌 1 = 𝜆1𝑋 1 + 𝑍 1

𝑌 2 = 𝜆2𝑋 2 + 𝑍 2

𝑘th RE 𝑘th RE

Feedback

𝒀 = 𝑯𝑿 + 𝒁 𝑯 𝑿 = 𝑽𝑿

Non Access-Stratum (NAS)

PDCP

RRC

MAC

RLC

PHY

RF

OAI-eNB


PDCP

RRC

MAC

RLC

PHY

RF

OAI-UE Master Branch Master Branch

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TM4 Basics in LTE

Modulated Symbols

Feedback

pmiq # of layer 1 (RI 0)

0 1

2

11

1 1

2

1−1

2 1

2

1j

3 1

2

1−j

Index 3: 1

2

1−𝑗

𝐻11

𝐻112 + 𝐻12

2 −𝑗𝐻12

𝐻12



𝑿= 𝑷𝑿

𝑯eff

=𝐻11 𝐻12

𝐻21 𝐻22𝑷

𝑋 1

𝑋 2

𝑌 1

𝑌 2

𝒀 = 𝑯eff𝑿 + 𝒁 𝑯 𝑿 = 𝑷𝑿


PDCP

RRC

MAC

RLC

PHY

RF

OAI-eNB


PDCP

RRC

MAC

RLC

PHY

RF

OAI-UE

Closed loop precoding in LTE:

Requires feedback from the UE

Rank indicator (RI)

Precoding matrix indicator (PMI)

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TM4 Basics in LTE

𝑿= 𝑷𝑿

𝑯eff

=𝐻11 𝐻12

𝐻21 𝐻22𝑷

𝑋 1

𝑋 2

Modulated Symbols

𝑌 1

𝑌 2

Feedback pmiq # of layer 2 (RI 1)

1 1

2

1 11 −1

2 1

2

1 1𝑗 −𝑗

𝜌21 = 𝐻12∗ 𝐻22

∗ 𝐻11

𝐻21

pmiq = 1, for Re(𝜌21) ≥ Im(𝜌21)

2, for Re 𝜌21 < Im(𝜌21)



PDCP

RRC

MAC

RLC

PHY

RF

OAI-eNB


PDCP

RRC

MAC

RLC

PHY

RF

OAI-UE

Closed loop precoding in LTE:

Requires feedback from the UE

Rank indicator (RI)

Precoding matrix indicator (PMI)

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TM4 Basics in LTE

𝑿= 𝑷𝑿

𝑯eff

=𝐻11 𝐻12

𝐻21 𝐻22𝑷

𝑋 1

𝑋 2

Modulated Symbols

𝑌 1

𝑌 2

Feedback

CQI/PMI reporting

UCI format CQI, PMI, and RI

UE measurements



PDCP

RRC

MAC

RLC

PHY

RF

OAI-eNB


PDCP

RRC

MAC

RLC

PHY

RF

OAI-UE

UE statistics

In OAI-eNB, we verify and review the MAC/PHY code to support:

MAC: format2 with 𝑁𝑙=1, 2

PHY: layer mapping of 1 codeword into 𝑁𝑙 layers

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PDCP

RRC

MAC

RLC

PHY

RF

OAI-eNB






PDCP

RRC

MAC

RLC

PHY

RF

OAI-UE

TM4 Basics in LTE

𝒀 = 𝑯eff𝑿 + 𝒁

𝑿= 𝑷𝑿

𝑯eff

=𝐻11 𝐻12

𝐻21 𝐻22𝑷

𝑋 1

𝑋 2

Modulated Symbols

𝑌 1

𝑌 2

Feedback

𝑯 𝑿 = 𝑷𝑿

CQI/PMI reporting

UCI format CQI, PMI, and RI

UE measurements UE statistics

In OAI-UE, we verify and review the PHY code to support:

lte_ue_measurements: CQI, PMI, and RI

ue_pdcch_procedures: format2 detection

generate_ue_dlsch_params_from_dci: extract format2 for DL decoding

ue_pdsch_procedures: rx_pdsch for processing 2 layers into 1 codeword

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Review of OAI-eNB Thread and PHY Procedures

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eNB: phy_procedures_eNB_TX openair1/SCHED/phy_procedures_lte_eNb.c

RB12

RB9

RB15

2

1

1

2

2

1

1

2

2

1

1

2

2

1

1

2

2

1

1

2

2

1

1

2

2

1

1

2

2

1

1

2

subframe 0

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PSS/SSS/PBCH: common_signal_procedures()

generate_pilots_slot()

generate_pss()/generate_sss()

generate_pbch(): SISO and Alamouti

HARQ_UL: synchronous ul_subframe=((subframe_tx+4)%10) ul_frame=(frame+(subframe_tx>=6 ? 1 :0)) harq_pid=(((ul_frame<<1)+ul_subframe)&7);

eNB: phy_procedures_eNB_TX openair1/SCHED/MAC/phy_procedures_lte_eNb.c

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eNB: TX (MAC+PDSCH)

phy_procedures_eNB_TX() openair1/SCHED/phy_procedures_lte_eNb.c

Logical channel Prioritization/Multiplexing

DCCH DCCH1

DTCH

DLSCH_pdu TBS

dlsch_encoding() crc, lte_segmentation, turbo_encoding,

rate_matching

DCI pdu

format1, format1A format2

schedule_RA

schedule_ulsch

schedule_ue_spec

schedule_SI

fill_DLSCH_dci

generate eNB_dlsch params() generate eNB_dlsch params_from_dci()

generate eNB_ulsch params() generate eNB_ulsch params_from_dci()

format0

eNB_dlsch_ulsch_scheduler() openair2/LAYER2/MAC/eNB_scheduler.c

Turbo Encoding LTE_TRANSPORT/dlsch_coding.c

𝐺 bits

allocate_res_in_RB()

𝐺/𝑄𝑚/𝑁𝑙 symbols

dlsch_ scrambling()

dlsch_ modulation()

𝐺 bits

LTE_TRANSPORT/dlsch_modulation.c

𝐺/𝑄𝑚 symbols

𝑋0𝑖 = 𝑄𝐴𝑀 𝑒 𝑄𝑚2𝑖, … , 𝑄𝑚2𝑖 + 𝑄𝑚 − 1 , 𝑖 = 0,… , 𝐺/𝑄𝑚 − 1

𝑋1𝑖 = 𝑄𝐴𝑀 𝑒 𝑄𝑚(2𝑖 + 1),… , 𝑄𝑚(2𝑖 + 1) + 𝑄𝑚 − 1 ,

𝑋0𝑖

𝑋1𝑖

pdsch_procedures() openair1/SCHED/phy_procedures_lte_eNb.c

For 𝑁𝑙=2 layers, dlsch0_harq->mimo_mode is configured based on tpmi

• TBS is assigned based on 𝑁𝑙 × 𝑛𝑏𝑟𝑏

• 𝐺 = (𝑛𝑏𝑟𝑏 ×𝑚𝑜𝑑𝑜𝑟𝑑𝑒𝑟 × ((14 − 𝑛𝑢𝑚𝑝𝑑𝑐𝑐ℎ𝑠𝑦𝑚𝑏𝑜𝑙𝑠) × 12 − 3 × 4) − 𝐺𝑎𝑑𝑗 ) × 𝑁𝑙

format2

nb_antenna_ports_eNB = 2

TBS1 off (mcs2 = 0, rv2 = 1) TBS0 on

tpmi=0 to 7


1

𝑋0

2

1


1

𝑋1

2

1

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MAC: schedule_ue_spec(module_idP,frameP,subframeP,mbsfn_flag) /openair2/LAYER2/MAC/eNB_scheduler_dlsch.c

Direction: E-UTRAN => UE

RLC Mode: AM (ARQ)

Logical Channel: DCCH-DTCH

Transport Channel: DL-SCH

• The eNB scheduler consists of a scheduling entity, a DL HARQ entity, and a multiplexing entity

• The scheduling entity supports resource requirement, assignment, and allocation (implemented in dlsch_scheduler_pre_processor())

• The transmit HARQ operation includes transmission and retransmission of TBs, and reception and processing of ACK/NACK signaling

• In OAI, synchronous HARQ is used for both the downlink and the uplink

harq_pid=((frame_tx ×10)+subframe_tx)&7

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MAC: dlsch_scheduler_pre_processor (module_idP, frameP, subframeP, N_RBG, mbsfn_flag) /openair2/LAYER2/MAC/pre_processor.c

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MAC: assign_rbs_required (module_idP,frameP,subframeP,nb_rbs_required[MAX_NUM_CCs][NUM_UE_MAX], min_rb_unit[MAX_NUM_CCs])

/openair2/LAYER2/MAC/pre_processor.c

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PHY: generate_eNB_dlsch_params_from_dci(): /openair1/PHY/LTE_TRANSPORT/dci_tools.c

TB1 OFF

(DCI2_5MHz_2A_FDD_t*)dci_pdu

DL Scheduling assignment for MIMO closed loop spatial multiplexing

tpmi=0: AlAMOUTI, Nl=1 tpmi=1: UNIFORM_PRECODING11 pmiq 0, Nl=1 tpmi=2: UNIFORM_PRECODING1m1, pmiq1, Nl=1 tpmi=3: UNIFORM_PRECODING1j , pmiq2, Nl=1 tpmi=4: UNIFORM_PRECODING1mj, pmiq3, Nl=1 tpmi=5: PUSCH_PRECODING0, Nl=2 tpmi=6: PUSCH_PRECODING1, Nl=2 tpmi=7: TM4_NO_PRECODING, Nl=2

rah rballoc TPC Harq pid Tb

swap

mcs

1

ndi1 rv1 mcs

2

ndi2 rv2 tpmi

1 13 2 3 1 5 1 2 5 1 2 3

0 rballoc tpc harq_pid mcs 1-oldNDI 0 0 1 0/7

TB0 ON

dlsch0=dlsch[0] dlsch1=NULL

dlsch0_harq->mimo_mode dlsch0_harq->Nl

dlsch0_harq->pmi_alloc

dlsch0_harq->nb_rb dlsch0_harq->TBS

eNB->UE_stats[UE_id]->DL_pmi_single

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eNB: TX (MAC+PDSCH)

phy_procedures_eNB_TX() openair1/SCHED/phy_procedures_lte_eNb.c

Logical channel Prioritization/Multiplexing

DCCH DCCH1

DTCH

DLSCH_pdu TBS

dlsch_encoding() crc, lte_segmentation, turbo_encoding,

rate_matching

DCI pdu

format1, format1A format2

schedule_RA

schedule_ulsch

schedule_ue_spec

schedule_SI

fill_DLSCH_dci

generate eNB_dlsch params() generate eNB_dlsch params_from_dci()

generate eNB_ulsch params() generate eNB_ulsch params_from_dci()

format0

eNB_dlsch_ulsch_scheduler() openair2/LAYER2/MAC/eNB_scheduler.c

Turbo Encoding LTE_TRANSPORT/dlsch_coding.c

𝐺 bits

allocate_REs_in_RB()

𝐺/𝑄𝑚/𝑁𝑙 symbols

dlsch_ scrambling()

dlsch_ modulation()

𝐺 bits

LTE_TRANSPORT/dlsch_modulation.c

𝐺/𝑄𝑚 symbols

𝑋0𝑖 = 𝑄𝐴𝑀 𝑒 𝑄𝑚2𝑖, … , 𝑄𝑚2𝑖 + 𝑄𝑚 − 1 , 𝑖 = 0,… , 𝐺/𝑄𝑚 − 1

𝑋1𝑖 = 𝑄𝐴𝑀 𝑒 𝑄𝑚(2𝑖 + 1),… , 𝑄𝑚(2𝑖 + 1) + 𝑄𝑚 − 1 ,

𝑋0𝑖

𝑋1𝑖

pdsch_procedures() openair1/SCHED/phy_procedures_lte_eNb.c

For 𝑁𝑙=2 layers, dlsch0_harq->mimo_mode is configured based on tpmi

• TBS is assigned based on 𝑁𝑙 × 𝑛𝑏𝑟𝑏

• 𝐺 = (𝑛𝑏𝑟𝑏 ×𝑚𝑜𝑑𝑜𝑟𝑑𝑒𝑟 × ((14 − 𝑛𝑢𝑚𝑝𝑑𝑐𝑐ℎ𝑠𝑦𝑚𝑏𝑜𝑙𝑠) × 12 − 3 × 4) − 𝐺𝑎𝑑𝑗 ) × 𝑁𝑙

format2

nb_antenna_ports_eNB = 2

TBS1 off (mcs2 = 0, rv2 = 1) TBS0 on

tpmi=0 to 7


1

𝑋0

2

1


1

𝑋1

2

1

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Review of OAI-UE Thread and PHY Procedures

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After synchronization, the flag start_rx_stream=0. Hence,

Correct rx_offest by capturing rx_offest samples from the USRP

UE->rx_offset=0; (sync with rx_offest)

UE->time_sync_cell=0; (sync with the cell)

Set UE->proc.proc_rxtx[th_id].frame_rx=0 (Ready to read frame 0)

Read the first OFDM symbol of the subframe 0 from the RF device

slot_fep(UE,0, 0, 0, 0, 0) for l=0

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After the first slot_fep(), the UE thread loops over subframe_rx=0, ..., 9

In each loop, the UE thread gets TTI samples from USRP

The UE thread wakes up the even or the odd UE_thread_rxn_txnp4 according to the subframe number

phy_procedures_UE_RX(): LTE UE Receiver

UE_MAC(): MAC layer of UE

phy_procedures_UE_TX(): LTE UE Transmitter

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UE: RX (PDCCH+PDSCH)

DCI pdu

generate_ue_dlsch_params_from_dci()

DL format 2: format2: Alamouti/TM4

ue_pdsch_procedures() LTE_TRANSPORT/dlsch_demodulation.c

rx_pdsch() rxdataF[0][ttioffest]

1

𝑌0[𝑘]

2

1

rxdataF[1][ttioffest]

1

𝑌1[𝑘]

2

1

ue_pdcch_procedures() openair1/SCHED/phy_procedures_lte_ue.c

rx_pdcch()

prepare_dl_decoding_format2_2A()

nb_rb = dlsch_extract

_rbs_dual

dlsch_scale_channel

dlsch_channel_level()

dlsch_channel_compensation

dlsch_detection_mrc

dlsch _alamouti

dlsch_qam_llr()

dci_cnt =

dci_decoding_procedure()

search all possible DCIs

rx_phich ()

is_phich_subframe generate_ue_ulsch_params_from_dci()

Format 1,1A, 2, ... Format 0

extract_dci2_info()

status = check_dci_format2_2a

_coherency()

generate_ue_dlsch_params_from_dci() LTE_TRANSPORT/dci_tools.c

𝑁𝑙 = 2

dlsch0_harq->mimo_mode tpmi:0 Alamouti tpmi: 7 test TM4

TBS0 on TBS1 off (mcs2 = 0, rv2 = 1) dlsch0_harq->Nl = 2 dlsch0_harq->mimo_mode = Alamouti/TM4_NO_PRECODING

lte_ue_measurements()

ue_ulsch_uespec_procedures()

RI + CQI/PMI reporting

UCI format: Wideband CQI1 (4 bits) PMI (14 bits)

TM4 postprocessor

ue_measurement_procedures() /openair1/SCHED/phy_procedures_lte_ue.c

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ue_measurement_procedures openair1/SCHED/phy_procedures_lte_ue.c

lte_ue_measurements(): OFDM symbol l=0 at every slot

Rx spatial power: rx_spatial_power[eNB_id][aatx][aarx] and rx_power_tot[eNB_id]

Rank Estimation: rank_estimation_tm3_tm4()

Signal and noise average power computation: rx_power_avg and n0_power_avg

CQI measurements: wideband_cqi_tot, wideband_cqi_avg, and rx_rssi_dBm

Subband CQI measurements: subband_cqi[eNB_id][aarx][subband], subband_cqi_tot[eNB_id][subband]

PMI measurements: subband_pmi_re[eNB_id][subband][aarx], subband_pmi_im[eNB_id][subband][aarx], wideband_pmi_re[eNB_id][aarx], and wideband_pmi_im[eNB_id][aarx]

ue_rcc_measurements(): OFDM symbol l=6 at subframe 0/subframe 5

Noise Floor Calculation: n0_power[aarx], n0_power_dB[aarx], n0_power_tot, n0_power_tot_dB, n0_power_tot_dBm

Reference Signal Rx power: rsrp and rssi

Additional measurements: every subfarme at slot 0 and OFDM symbol 4

phy_adjust_gain(): AGC

lte_adjust_synch(): Accum/filtering time offest estimation

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The received quantized OFDM samples can be expressed as

𝑦 𝑛 =𝑃𝑟𝒙𝐴𝐺

2

2 𝑋𝑘𝑒

𝑗2𝜋𝑘𝑛/𝑁𝑁−1𝑘=0 + 𝑧[𝑛], 0 < 𝑛 < 𝑁 − 1

where 𝑃𝑟𝑥 denotes the power of the received passband signal and 𝐴𝐺 is the voltage Gain of the USRP

The samples of 𝑧[𝑛] are complex-valued Gaussian RVs with zero mean and variance (power) 1

2𝑁0𝐹 × 𝑁∆𝑓

The quantized IQ samples are represented by 16-bit short integers (1 bit: sign and 15 bits: fixed point representation)

I Q

16 bits 16 bits +1

−1

𝑅 = 2

𝑦(𝑡) 𝑦[𝑛]

𝑦𝑞[𝑛]

𝑛𝑇𝑠 𝑡

• The quantization width is given by:

𝑄 =𝑅

216 =

1

215 = 30 𝜇V

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2

2 𝑋𝑘𝑒

𝑗2𝜋𝑘𝑛/𝑁𝑁−1𝑘=0 + 𝑧[𝑛], 0 < 𝑛 < 𝑁 − 1




512 subcarriers×32 bits (I/Q 16 bits per samples input OFDM discrete signal)

nb prefix samples (40 or 36)

rx_offset &common_vars->rxdata[aa]

[rx_offset % frame_length_samples]

512-DFT operation

&common_vars_rx_data_per_thread.rxdataF[aa]

[frame_parms->ofdm_symbol_size*symbol]

Channel Estimation

If(l==0|l==4) Pilot positions

slot_fep() signal processing

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2

2 𝑋𝑘𝑒

𝑗2𝜋𝑘𝑛/𝑁𝑁−1𝑘=0 + 𝑧[𝑛], 0 < 𝑛 < 𝑁 − 1




512 subcarriers×32 bits (I/Q 16 bits per samples input OFDM discrete signal)

nb prefix samples (40 or 36)

rx_offset &common_vars->rxdata[aa]

[rx_offset % frame_length_samples]

512-DFT operation

&common_vars_rx_data_per_thread.rxdataF[aa]

[frame_parms->ofdm_symbol_size*symbol]

Channel Estimation

If(l==0|l==4) Pilot positions l=0

l=4

𝑌𝑘 = 1

𝑁 𝑦𝑛

𝑁−1

𝑛=0

𝑒−𝑗2𝜋𝑘𝑛/𝑁

0

6∆𝑓

0 6∆𝑓 𝑓𝑠 = 𝑁∆𝑓

𝑌𝑘

𝐴 𝑁

…

𝐴 𝑁

𝐴 =𝑃𝑟𝒙𝐴𝐺

2

2

slot_fep() signal processing

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𝑦 𝑛 =𝑃𝑟𝒙𝐺𝐴

2 𝑋𝑘𝑒

𝑗2𝜋𝑘𝑛/𝑁𝑁−1𝑘=0 + 𝑧[𝑛], 0 < 𝑛 < 𝑁 − 1

where 𝑃𝑟𝑥 denotes the power of the received passband signal and 𝐺𝐴 is the voltage Gain of the USRP



l=0

l=4 0

6∆𝑓

0 6∆𝑓 𝑓𝑠 = 𝑁∆𝑓

𝑌[𝑘]

𝐴 𝑁

…

𝐴 𝑁

𝐴 =𝑃𝑟𝒙𝐺𝐴

2

Reference Signal Rx power: rsrp and rssi

rsrp = 1

𝑁𝐸 𝑌[𝑘] 2 = 𝐴2, 𝑘 ∈ pilots

= 1

2𝑃𝑟𝒙𝐺𝐴 × 230 (W/RE)

where 𝐺𝐴(dB) = 𝑈𝐸𝑟𝑥𝑔𝑎𝑖𝑛 − 𝑈𝑆𝑅𝑃𝑂𝑓𝑓𝑒𝑠𝑡 is

the RX gain of the USRP rssi = RSRP × 12 ∗ 𝑁𝑅𝐵

𝐷𝐿

𝑌𝑘 = 1

𝑁 𝑦𝑛

𝑁−1

𝑛=0

𝑒−𝑗2𝜋𝑘𝑛/𝑁

• The max gain for RX on the AD936x is 76 dB, for TX 89 dB

• The ranges can be printed out when you run 'uhd_usrp_probe' for any USRP

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𝑦 𝑛 =𝑃𝑟𝒙𝐺𝐴

2 𝑋𝑘𝑒

𝑗2𝜋𝑘𝑛/𝑁𝑁−1𝑘=0 + 𝑧[𝑛], 0 < 𝑛 < 𝑁 − 1



Noise Floor Calculation: 𝑛0𝑝𝑜𝑤𝑒𝑟(𝑎𝑎𝑟𝑥) and 𝑛0𝑝𝑜𝑤𝑒𝑟𝑡𝑜𝑡

𝑛0𝑝𝑜𝑤𝑒𝑟 𝑎𝑎𝑟𝑥 = 𝐸 𝑍𝑎𝑎𝑟𝑥 𝑘 2 , 𝑘 ∈ null RE SSS/PSS

=1

2𝑁0𝐹 × 𝑁∆𝑓 × 230 (W)

where 𝑁0𝐹 = −174 dBm/Hz + 𝑵𝑭 dB + 𝐺𝐴(dB) and 𝐺𝐴(dB) = 𝑈𝐸𝑟𝑥𝑔𝑎𝑖𝑛 − 𝑈𝑆𝑅𝑃𝑂𝑓𝑓𝑒𝑠𝑡 is the RX gain of the USRP

RB12

RB9

RB15

Subframe0/5, slot0, at l=5,6

Null REs

• The max gain for RX on the AD936x is 76 dB, for TX 89 dB

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The MIMO channel: 𝑯(𝑘) =𝐻11[𝑘] 𝐻12[𝑘]

𝐻21[𝑘] 𝐻22[𝑘]

𝑨MF(𝑘) = 𝑯∗ 𝑘 𝑯 𝑘

=𝐻11

2 + 𝐻212 𝐻11

∗ 𝐻12 + 𝐻21∗ 𝐻22

𝐻12∗ 𝐻11 + 𝐻22

∗ 𝐻21 𝐻122 + 𝐻22

2

The eignvalues of 𝑯 are related to those of 𝑨MF as

𝜆𝑖 = 𝛽𝑖 , 𝑖 = 1, 2

For a unitary matrix, the condition number 𝜖 𝑘 ≡𝜆max𝜆min

= 1, conddB 𝑘 = 0 dB

In OAI, the condition number:

𝜖 𝑘 =𝑨MF(𝑘)

2

det(𝑨MF 𝑘 )

conddB[𝑘] = numerdB(𝑘) − denumdB(𝑘) If conddB 𝑘 ≤ 5 dB, hence, Rank=2

𝜖 𝑘 =𝛽max

𝛽min

=

Rank Indicator (RI)





(𝐻11, 𝐻12, 𝐻21, 𝐻22, 𝑁𝑅𝐵)

rank_estimation

_tm3_tm4

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The UE computes

𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑝𝑚𝑖𝑟𝑒/𝑖𝑚 𝑠𝑢𝑏𝑏𝑎𝑛𝑑 𝑛𝑟𝑥 = 𝐸 𝐻𝑛𝑟𝑥1 𝑘 𝐻𝑛𝑟𝑥2∗ 𝑘 ,

𝑛𝑟𝑥 = 1, 2

The correlation coefficient

𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑝𝑚𝑖𝑟𝑒/𝑖𝑚 𝑠𝑢𝑏𝑏𝑎𝑛𝑑 += 𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑝𝑚𝑖𝑟𝑒/𝑖𝑚 𝑠𝑢𝑏𝑏𝑎𝑛𝑑 𝑛𝑟𝑥

Precoding for (rank =1) TM4

𝑝𝑚𝑖𝑣𝑒𝑐𝑡 | = 𝑝𝑚𝑖𝑞 << (2 ∗ 𝑖), for 𝑖 = 0,… , 𝑛𝑏𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑠 − 1

PM Indicator (PMI)





RB 21

RB 20

RB 23

RB 22

RB 24

RB 3

RB 2

RB 1

RB 0

0

5

6

pmiq

pmiq

pmiq

𝜃𝑝𝑚𝑖𝑟𝑒/𝑖𝑚: (45o, 135o)

Index 2: 1

2

1𝑗

real axis

Imaginary axis


Index 1: 1

2

1−1


Index 3: 1

2

1−𝑗

𝜃𝑝𝑚𝑖𝑟𝑒/𝑖𝑚: (45o, −45o)

Index 0: 1

2

11

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The UE computes

𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑝𝑚𝑖𝑟𝑒/𝑖𝑚 𝑠𝑢𝑏𝑏𝑎𝑛𝑑 𝑛𝑟𝑥 = 𝐸 𝐻𝑛𝑟𝑥1 𝑘 𝐻𝑛𝑟𝑥2∗ 𝑘 ,

𝑛𝑟𝑥 = 1, 2

The correlation coefficient

𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑝𝑚𝑖𝑟𝑒/𝑖𝑚 𝑠𝑢𝑏𝑏𝑎𝑛𝑑 += 𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑝𝑚𝑖𝑟𝑒/𝑖𝑚 𝑠𝑢𝑏𝑏𝑎𝑛𝑑 𝑛𝑟𝑥

Precoding for (rank =2) TM4

𝑝𝑚𝑖𝑣𝑒𝑐𝑡 | = (𝑝𝑚𝑖𝑞 − 1) << 𝑖, for 𝑖 = 0, … , 𝑛𝑏𝑠𝑢𝑏𝑏𝑎𝑛𝑑𝑠 −1

PM Indicator (PMI)





RB 21

RB 20

RB 23

RB 22

RB 24

RB 3

RB 2

RB 1

RB 0

0

5

6

pmiq

pmiq

pmiq

pmiq # of layer 2 (RI 1)

1 1

2

1 11 −1

2 1

2

1 1𝑗 −𝑗

𝜌21 = 𝐻12∗ 𝐻22

∗ 𝐻11

𝐻21

pmiq = 1, for Re(𝜌21) ≥ Im(𝜌21)

2, for Re 𝜌21 < Im(𝜌21)

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TM4 Setup and Results

OAI-eNB U

SRP

B210

IF5 URU

USRP

B210

OAI-UE

Shared UE-Side Distributed Antenna System

RI and 𝐶𝑄𝐼/𝑃𝑀𝐼

Feedback

ue_TransmissionMode=4

--fh IF5

Multiple UEs

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UE Statistics

Noise Floor Calculation:

𝑛0𝑝𝑜𝑤𝑒𝑟 𝑎𝑎𝑟𝑥 =1

2𝑁0𝐹 × 𝑁∆𝑓 × 230 (W)

where 𝑁0𝐹 = −174 dBm/Hz + 𝑵𝑭 dB + 𝐺𝐴(dB) and 𝐺𝐴(dB) = 𝑈𝐸𝑟𝑥𝑔𝑎𝑖𝑛 − 𝑈𝑆𝑅𝑃𝑂𝑓𝑓𝑒𝑠𝑡 is the RX gain of the

USRP

RI=1 (2 layers)

implementation of tm4 into oai softmodem · pmiq # of layer 2 (ri 1) 1 1 2 s s s− s 2 1 2 s s −...

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