ieee fdd test result

Throughput, Capacity, Handover and LatencyPerformance in a 3GPP LTE FDD Field Trial

Marilynn P. Wylie-Green, ∗ Tommy Svensson,†∗Nokia Siemens Networks; Irving, Texas, 75063; E-mail: [email protected]

†Department of Signals and Systems, Communication Systems GroupChalmers University of Technology; SE-412 96 Gothenburg, Sweden; Email: [email protected]

Abstract— This article presents a summary of 3GPP LongTerm Evolution (LTE) radio system performance during theexecution of a multi-site field trial. This exhaustive testingcampaign, performed over the lower 700 MHz and 2 GHz bands,includes a battery of stationary and mobility throughput cases,multi-user capacity scenarios, handover performance and latencytests, that have been designed to reveal LTE radio performanceunder a variety of realistic user scenarios. Tests have beenperformed using a Category 2 LTE UE, which can handle amaximum transport of 50 Mbps in the downlink and 25 Mbpsin the uplink.

As the results indicate, the system boasts a peak downlinksingle-user throughput in excess of 49 Mbps and a peak uplinksingle-user throughput observed of 19 Mbps, which is quite closeto the theoretical uplink limit of 21 Mbps. In multi-user scenarioswith four active users, in the best case, we have measured a cellthroughput of 47 Mbps in the downlink and 20 Mbps in theuplink, which is close to the theoretical best. Finally, as we show,the system achieves a handover success rate of 100% and a bestcase average user plane latency of 22ms.

I. INTRODUCTION

Long Term Evolution (LTE) is considered to be one of thekey standards on the roadmap to 4G wireless communicationsthat started with today’s 2G and 3G networks. Built on thetechnical foundation of the family of 3GPP standards, theLTE air interface has been optimized to yield higher spectralefficiency and shorter latencies by the combined use of linkadaptation, advanced modulation, multiple antenna transmis-sion technologies and a converged core [1], [2]. From the radiointerface perspective, ambitious targets have been defined forLTE, which include scalable bandwidth from 1.25 MHz up to20 MHz, peak data rates up to 100 Mbps for the downlinkand 50 Mbps for the uplink, and a capacity increase of 2− 4times that of HSPA/Rel. 6 [3].

One of the key features of LTE is fast link adaptation, whichis facilitated through the use of a sizeable modulation andcoding set (MCS) that supports the use of QPSK, 16-QAMand 64-QAM. In addition, LTE also supports both single-stream and multi-stream MIMO transmission modes [4]. Bydefault, LTE uses 2 transmitting (Tx) antennas at the eNodeB(eNB) side and 2 receiving (Rx) antennas at the UE side.However, future systems may implement 4×4 MIMO antennaconfigurations and UE Category Class 51 to achieve even

1A Category 5 LTE UE can handle a maximum transport of 300 Mbps inthe downlink and 50 Mbps in the uplink. It can also work with 4× 4 MIMOconfigurations.

higher throughputs. The summary of the theoretical peak datarates for both uplink and downlink configurations over themaximum 20 MHz bandwidth is displayed in Table (I).

TABLE I

THEORETICAL THROUGHPUT (MBPS) OVER 20 MHZ LTE BANDWIDTH

Direction Ant. Config. Max. PRBs Max. MCS ID Peak L1 TputDL 2 × 2 MIMO 50 28 73.40UL 1 × 2 SIMO 45 20 20.62

OFDMA has been selected as the air interface solution forthe downlink and single carrier FDMA (SC-FDMA) has beenselected for the uplink [5] due to its enhanced power efficiency,which prolongs battery life.

The evolution from today’s hybrid circuit switched andpacket switched networks to the all-IP (Internet Protocol)environment that LTE offers provides a rich opportunity forreduced delivery of costs for many new applications thatcombine voice, video and data services. In fact, the currentdemand for these enhanced services is a compelling motivationfor the near-term deployment of LTE.

Commerical deployment is expected in 2010, and there arenumerous field trials underway that are being conducted inorder to assess radio and core network performance, an exam-ple of which is the recent LTE field trial performed by NokiaSiemens Networks that is discussed in this paper. Several keymetrics of performance are presented, including single-userthroughput for both downlink and uplink TCP (TransmissionControl Protocol) and UDP (User Datagram Protocol) datatransfers, multi-user cell capacity, handover performance anduser-plane latency. Performance is investigated over the 2 GHzand (lower) 700 MHz bands.

The rest of this paper is organized as follows. In Section II,we describe the configuration of the two field test areas thathave been used for the field trial as well as the baseline LTEFDD (Frequency Division Duplexing) parameters. Section ??describes the approach used to generate traffic in the networkin order to test performance under 0% and 50% loadingscenarios. In Section III, we describe how the locations areselected for stationary tests. In Section IV, the field test resultsfor a battery of tests are presented and finally in Section V, weprovide a summary of the field trial results that are presentedin this paper.

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This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE Globecom 2010 proceedings.

TABLE II

LTE FDD PARAMETERS

Parameter ValueTx Power DL 30W / antennaMaximum Tx Power UL 23 dBmBandwidth 10 MHzNumber of Resource Blocks 50Category 2 LTE UE DL: 50 Mbps; UL: 25 Mbpsa

DL Band (2 GHz) 2.110 - 2.155 GHzUL Band (2 GHz) 1.710 - 1.755 GHzDL Band (700 MHz) 734 - 746 MHzUL Band (700 MHz) 704 - 716 MHzDL Modulation Schemes OFDM(64-QAM, 16-QAM, QPSK)UL Modulation Schemes SC-FDMA(16-QAM, QPSK)DL Antenna Schemes 2 × 2 MIMO, SIMOUL Antenna Schemes SIMO (Rx Diversity)Target BLER 10%Adaptive MIMO Tx Diversity, Spatial MultiplexingNeighbor Loading 0% and 50%Adaptive Modulation & Coding On

aUse of the Category 2 UE imposes a 50 Mbps restriction for downlinkdata transmissions and a 25 Mbps limitation for uplink data transmissions.

II. MULTI-SITE FIELD TESTING AREA

DX0309_2 Victim Cell

DX4169_3Victim Cell

Fig. 1. Multi-site field test area. Tests over the 2 GHz band are conductedwithin Cluster A, (enclosed in the right orange polygon) while tests over theLower 700 band are performed within Cluster B (enclosed in the left blackpolygon).

The trial area consists of two geographically distinct areas,denoted Cluster A and Cluster B, as shown in Fig. (1).Within Cluster A, LTE radio performance is tested using NokiaSiemens Networks equipment over the 2 GHz band using theportion of the network that encloses sites DX0350, DX3089,DX0309, DX4022, DX0115, DX4072 and DX0729. As shownin the Figure, of these seven eNodeB’s, six of them implementtriple RF modules while site DX0389 radiates using two RFmodules (since the unradiated sector faces outside of the testarea). Hence, there are a total of twenty active sectors withinCluster A. The victim site for all testing in Cluster A is thebeta sector of DX0309 (represented at DX03092).

Cluster B contains the region in which tests are executedusing Nokia Siemens Networks equipment over the Lower 700MHz band. In this area, there are four eNodeB’s (DX0043,DX4182, DX4133 and DX4109), all of which implement tripleRF modules and the victim site is the gamma sector of siteDX4109 (denoted DX41093). In total, there are twelve activelyradiating sectors in this cluster.

The baseline LTE FDD parameters used during the LTEfield trial are summarized in Table II.

0.27 Km, 0.17 Mi

1.24 Km, 0.77 Mi

1.82 Km, 1.13 Mi

Mid Location

Near Location

Far Location

DX0309

Fig. 2. Near, Mid and Far Locations used for testing stationary throughputperformance during the LTE technology field trial.

The transport network architecture allows the data fromeach eNodeB to be routed through the MPLS (MultiprotocolLabel Switching) network by using a single 100Mbps/GigElink. The MME (Mobility Management Entity), P-GW (PacketGateway) and S-GW (Serving Gateway) are operated within anLTE 4G Laboratory in Dallas, Texas where the core networkfor this trial is emulated using Nokia Siemens Networksequipment.

During the field trial, two specific loading scenarios havebeen utlized for both uplink and downlink: 0% loading and50% loading.

In downlink tests, the interference has been generated at thedesired loading level by sending dummy data on 50% of thePRBs. Under unloaded downlink conditions, the average SINRmeasured at these same three locations increases relative to theaverage SINR under loaded conditions (most significantly inthe Far position).

For the uplink loaded scenarios, the solution has been to usea commercial vector signal generator to create standardizedwaveforms for 3GPP LTE FDD.

III. TEST LOCATION SELECTION FOR STATIONARY

PERFORMANCE TESTING

In order to test performance within each Cluster, threedistinct locations (Near, Mid and Far) have been defined basedon the measured downlink wideband SINR2 measured under50% loading conditions on the neighbor sites. The SINRthresholds used for delineation between the Near, Mid andFar locations for all stationary tests are described in (1):

Near: 25 > SINR (dB) > 20Mid: 15 > SINR (dB) > 10Far: 5 > SINR (dB)

(1)

The Near, Mid and Far positions and their distances from thevictim site in Cluster A is shown in Fig. (2).

The data from drive tests conducted along the mobilityroute in Cluster A have been used to calculate the distribution

2We note that the SINR, which is not a 3GPP standardized metric, has beenmeasured using an LTE scanner.

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0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SINR (dB)

CD

F

DL LoadedDL UnloadedUL LoadedUL Unloaded

Fig. 3. Uplink and Downlink SINR Distributions along the drive route inCluster A.

of SINRs within the two victim sites. Results are displayedin Figs. 3. A rather higher range of SINRs is seen withinthis test area. This is due in part to the predominance ofthe suburban-rural propagation characteristics. In addition, thenetwork deploys a high transmit power at the eNB (i.e.,30W/antenna) and the usage of a mast head antenna (MHA),which introduces a significant improvement on the uplinksignal power.

A comparison of the average SINR in the loaded versusunloaded cases reveals an approximately 3 dB shift of themedian for both uplink and downlink scenarios.

IV. FIELD TEST PERFORMANCE RESULTS

A. Downlink Single User Throughput (Adaptive MIMO)

In this section, we report performance of the downlinksingle user throughput tests performed within Cluster A overthe 2 GHz band. The overall objective of these tests is tomeasure the downlink single-user throughput performancewhen utilizing adaptive 2×2 MIMO for a series of stationaryand mobility tests, under 0% and 50% neighbor cell loadingand using either the TCP or UDP protocol.

TCP is one of the main protocols in TCP/IP networks,enabling two hosts to establish a connection and exchangestreams of data. TCP guarantees delivery of data and alsoguarantees that packets will be delivered in the same order inwhich they are sent. In comparison, UDP is a connectionlessprotocol that also runs on top of IP networks. Unlike TCP/IP,however, UDP/IP provides very few error recovery services.

The performance results for test cases THP-001 - THP-016 (inclusive) are reported in Table. (III). There, we displaythe peak and average Layer 1 (L1) throughput as well asthe application layer (either TCP or UDP) throughput as thekey metrics of performance. Note that the stationary testinglocations corresponding to the Near, Mid and Far positionsfor the stationary tests (THP-001 - THP-006 and THP-009

- THP-014) is depicted in Fig. (2). The drive route used formobility testing (i.e., THP-007, THP-008, THP-015 and THP-016) is also shown in Fig. (2).

As expected, the overhead that is present in the transmissionof UDP IP datagrams is minimal (typically in the neighbor-hood of 1.5% for UDP versus 3% for TCP) and we generallyexpect for the application layer throughput achieved duringthe UDP-centric test cases (THP-002, THP-004, THP-006 andTHP-008) to exceed that achieved in the counterpart TCP-centric test cases (THP-001, THP-003, THP-005 and THP-007). This is indeed observed in the aforementioned test caseresults.

The maximum of the Peak L1 data rates occurs duringexecution of THP-001 and in THP-008, where the measured49.04 Mbps outcome comes within 1.9% of the theoreticalmaximum of 50 Mbps (which is imposed by the use of theCategory 2 LTE UE).

As a final note on the unloaded test cases, we illustratethe time evolution of the throughput, BLER and MCS ID formobility test case THP-008. Fig. (4) simultaneously displaysthe throughput (blue curve) and the BLER (red curve) duringthe drive test. In Fig. (5), the corresponding MCS ID allocationfor each codeword is shown. When both codewords are active(i.e., when the MCS ID for Codeword 2 is not equal to 0),then the system is employing spatial multiplexing to exploitthe favorable radio conditions. Higher throughput (close tothe maximum of 50 Mbps) is consequently attained due tothe use of dual streams to the UE. In other time epochswhen the throughput decreases due to the degradation in thereceived signal along the mobility route, then the MCS IDfor Codeword 2 is equal to 0 and the system is deployingtransmit diversity. The trigger for switching between transmis-sion modes is dependent on the rank indicator as well as theCQI (Channel Quality Indicator). Here, the adaptation of theradio resource manager in order to maintain a target BLER of10% after HARQ retransmissions is achieved by manipulatingthe modulation and coding scheme and other parameters notshown (such as resource block allocation). These results areindicative of the robustness of the LTE parameter allocationas the LTE UE moves through various radio environments.

As anticipated, the 50% loading most significantly impactsthe system performance when the UE is located in the Far Po-sition, it has less impact when it is located in the Mid position,and it has the least impact to test results in the Near Position.In fact, results show that the impact of introducing the loadingin the Far position is to decrease the average L1 throughputby 0.12% (THP-001 versus THP-009), a corresponding 25.7%decrease in the Mid position (THP-003 versus THP-011) anda 57.2% decrease in the Far position.

B. Uplink Single User Throughput (SIMO)

In this section, we discuss the performance of uplink single-user throughput testing under 0% and 50% loading in theuplink. The relevant test cases are THP-017 - THP-032,inclusive. As noted earlier, the Near, Mid and Far positionsare selected based on the downlink SINR measurements that

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TABLE III

SINGLE USER THROUGHPUT PERFORMANCE IN CLUSTER A OVER 700 MHZ.

Near Position Medium Position Far Position MobilityMbps Peak L1 Tput Ave L1 Tput Ave Appl Tput Peak L1 Tput Ave L1 Tput Ave Appl Tput Peak L1 Tput Ave L1 Tput Ave Appl Tput Peak L1 Tput Ave L1 Tput Ave Appl Tput

DL

TCPUnloaded

THP001 THP003 THP005 THP00749.04 48.24 46.62 48.7 47.10 46.19 42.94 41.08 39.78 48.94 30.59 29.89

LoadedTHP009 THP011 THP013 THP015

48.99 48.18 46.56 37.00 35.00 31.80 19.94 17.55 16.93 48.99 26.71 26.58

UDPUnloaded

THP002 THP004 THP006 THP00849.04 48.80 47.65 48.80 48.30 47.80 43.08 41.57 41.04 49.04 36.89 36.90


49.04 48.50 47.80 27.88 25.43 24.91 18.64 13.65 13.35 49.04 27.40 26.69

UL

TCPUnloaded

THP017 THP019 THP021 THP02318.89 18.83 18.23 18.89 18.53 17.93 4.30 3.70 3.60 18.99 12.88 11.93


18.89 18.78 18.18 18.89 18.66 18.20 3.60 2.18 2.10 18.87 11.60 11.54

UDPUnloaded

THP018 THP020 THP022 THP02418.89 18.86 18.39 18.89 18.55 18.30 5.10 4.07 4.00 18.99 12.10 11.88


18.89 18.80 N/A 18.89 18.66 18.40 4.26 3.70 N/A 18.99 12.44 N/A

0 100 200 300 400 500 600 700 800 9000

5

10

15

20

25

30

35

40

45

50

Time (s)

Throughput (Mbps); BLER (%)

BLER

Throughput

Fig. 4. L1 Throughput (upper blue curve) and BLER (lower red curve)measured during downlink mobility drive test THP-008.

0 100 200 300 400 500 600 700 800 9000

10

20

30MCS ID Codeword 1

Time (s)

MCS ID

0 100 200 300 400 500 600 700 800 9000

10

20

30

40MCS ID Codeword 2

Time (s)

MCS ID

Fig. 5. MCS ID allocation during mobility downlink throughput test. Eachtime series represents the MCS ID for a different codeword. (Taken fromTHP-008).

are made under 50% neighbor site (i.e., downlink) loadingconditions.

During the trial, the uplink MCS ID is limited to a maximumvalue of 20 and the maximum number of PRBs (PhysicalResource Blocks) that can be assigned is 48 (since 2 PRBs areused for PUCCH signalling). Hence, the peak uplink through-put per TTI (transmission time interval) can be calculated asfollows:

Tuplink,peak =TBSmax[bits/ms] × 1000[ms/s]

106Mbps

TBSmax = 20616 bits/ms

Tuplink,peak = 20.616Mbps (2)

In the Near position (THP-017, THP-018, THP-025 and THP-025), the peak L1 throughput is 18.89 Mbps, which comesquite close to the maximum of 20.616 Mbps.

An unanticipated result is found in the direct comparison ofTHP-019 and THP-027, where it is observed that the averageL1 throughput for the unloaded case is slightly lower than thesame performance metric recorded for the loaded case (18.53Mbps versus 18.66 Mbps). The lower throughput appears tobe due to TCP variations.

In the Far position test cases (THP-021, THP-022, THP-029 and THP-030), the recorded throughputs are all less than5 Mbps. During the LTE field trial, uplink power control hasbeen restricted to the use of Open Loop Power Control only.Hence, this performance is expected to improve drasticallywith the implementation of Closed Loop Power Control, asdescribed in [6]. Analysis of THP-021 and THP-022 revealsthat the LTE UE is assigned 8-10 PRBs, the MCS ID remainsrelatively constant at 20 (the maximum) and the BLER ismaintained at < 1%. (Recall that the target BLER is 10%).

C. Multi-User Throughput Test Cases

In the previous section, we have reported the performanceof the single-user throughput test cases, wherein a single UEis under test in the cell. In this section, however, we focuson several multiple user scenarios, in which four UEs aresimultaneously active within the cell. The relevant test casesare THP-033, THP-034, THP-037 and THP-038. Results aredisplayed in Fig. (IV). Due to the lack of space, we reportonly the results of downlink stationary multi-user testing.

Tests were executed using four LTE UEs, each in a differentlocation within the victim cell. For these tests, UE1 is located

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TABLE IV

THROUGHPUT PERFORMANCE FOR MULTI-UE TESTS.

Tput in Mbps Stationary Mobility, Variable SINRDirection Appl. Load Test Case Ave. Total Cell Tput Test Case Ave. Total Cell Tput

DL

TCP Unloaded THP033 46.61 THP035 Not TestedTCP Loaded THP037 37.67 THP039 44.99UDP Unloaded THP034 41.22 THP036 39.3UDP Loaded THP038 29.64 THP040 31.77

UL

TCP Unloaded THP041 19.40 THP043 17.91TCP Loaded THP045 17.68 THP047 18.20UDP Unloaded THP042 19.43 THP044 17.90UDP Loaded THP046 20.09 THP048 18.29

in the Far position, UE2 and UE4 are located in the Midposition and UE3 is situated in the Near position.

In all of these test cases, the four users share the 50available PRBs over the 10 MHz LTE bandwidth, and the radioresource manager allocates resources using the ProportionalFair scheduling algorithm [7]. The key observations are as fol-lows. When comparing the loaded to unloaded TCP scenarios(THP-033 versus THP-037), the reduction in the average totalcell throughput due to loading is 19%, while for the UDPscenarios (THP-037 versus THP-038), the reduction in theaverage total cell throughput due to loading is 28%. Solidthroughput performance is also observed for these test cases.

D. Throughput with Handover (2 GHz and 700 MHz)

In this final section, we discuss the results of testingthroughput performance with handover. Tests are conductedover both the 2 GHz and Lower 700 MHz bands withinCluster B. The relevant test cases are: CC-021, CC-022, CC-0210, CC-022 and CC-052. The objective of these tests is toimplement intra- and inter-eNodeB handover based on RRC(Radio Resource Control) messaging while imposing minimalimpact to the Layer 1 and Application Layer throughputbefore, during and after handover completion. In addition, thenetwork should succesfully execute control plane messagingwhile observing an interruption time that is less than 56ms (a requirement based on laboratory testing and productspecification).

In this series of tests, a successful handover is determinedby verifying the message sequence: Measurement Report sentfrom UE indicating a PCI (Physical Celll Identifier) withstrong signal, followed by source cell sending RRCConnec-tionReconfiguration message with MobilityControlInfo for thetarget cell and C-RNTI (Cell Radio Network Temporary Iden-tifier) to the user. Finally, this sequence should be followedby a RRCConnectionReconfigurationComplete message sentfrom the UE after it arrives at the target cell. The interruptiontime refers to the control-plane interruption time during thehandover. It is determined by the time at which the UE receivesthe RRCConnectionReconfiguration message in the source cellto the time at which it sends the RRCConnectionReconfig-urationComplete message in the target cell. At this point,the default radio bearer is established and is available forscheduling traffic by the target cell.

Although the CC-022 uplink drive tests had long durationsof time in which there was low throughput and many ping

TABLE V

HANDOVER RESULTS

Band Test Case LoopHOAttempts

HO Suc-cesses

HOSuccessRate

Ave. In-terruptionTime (ms)

L1 TputAvg/Peak

Appl TputAvg/Peak

2 GHz1 28 28 100% 21 10.7 / 13.7 9.7 / 13.5

CC021 DL 2 30 30 100% 21 10.7 / 14.8 9.6 / 12.93 29 29 100% 22 10.6 / 14.2 9.3 / 13.9

2 GHz1 31 31 100% N/A 10.7 / 13.7 9.7 / 13.5

CC022 UL 2 28 28 100% N/A 4.7 / 13.1 4.2 / 12.63 35 35 100% N/A 4.6 / 13.0 9.6 / 12.8

700 MHz1 36 36 100% 22 10.6 / 14.0 9.6 / 13.2

CC210 DL 2 28 28 100% 22 10.7 / 14.7 9.6 / 12.83 30 30 100% 22 10.7 / 14.3 9.6 / 13.9

700 MHz1 34 34 100% 21 9.1 / 13.2 8.8 / 12.8

CC220 UL 2 28 28 100% 21 9.7 / 13.0 9.4 / 12.83 34 34 100% 21 9.7 / 13.1 9.4 / 12.7

700 MHz CC052 DL 1 26 26 100% 21 10.8 / 13.9 9.6 / 13.1700 MHz CC052 UL 1 26 26 100% 21 9.6 / 13.0 9.4 / 12.6

TABLE VI

USER PLANE LATENCY SUMMARY

Near UE Far UELoad Test Case Size (Bytes) Direction Min Ave Max Min Ave Max

Load

CC1091 32 UE to Server 15 23 37 18 24 40CC1092 1400 UE to Server 23 45 269 28 38 55CC1093 32 Server to UE 17 23 33 16 24 40CC1094 1400 Server to UE 22 152 1166 26 36 68

Unloaded

CC1081 32 UE to Server 14 22 28 14 23 36CC1082 1400 UE to Server 22 30 37 25 40 181CC1083 32 Server to UE 17 28 459 16 36 1175CC1084 1400 Server to UE 23 41 871 27 36 56

pongs occurring, overall, the results are very impressive witha 100% success rate in 397 total handover attempts, and verylittle observable impact to the throughput. The average controlplane handover time of 21 ms is much faster than the targetedmaximum of 56 ms.

E. U-Plane Latency (700 MHz)

In this section, we describe the user plane latency testcases. The cases under review are: CC-1081U, CC-1082U,CC-1083U, CC-1084U, CC-1091U, CC-1092U, CC-1093Uand CC-1094U. In each of the test cases, the UE or serversends one ping request every second and in total, there arearound 100 pings that are executed. The summary of latencyresults for each test is shown in Table VI.

The expected average user plane latency for a 1400 byteping and assuming no HARQ retransmissions is 35 ms for theNear position UE and 43ms for the Far position UE (assuming1 HARQ retransmission in either the uplink or downlink). Fora 32 byte ping, the expected average user plane latency for theNear position UE is 24 ms and 32 ms for the Far position UE(assuming 1 HARQ retransmission in either the uplink or thedownlink). This delay is calculated in consideration of variousfactors, such as the delay in periodic scheduling requests onthe PUCCH, processing of Buffer Status Report (BSR) andqueuing.

It is observed that in some cases, the ping RTT (RoundTrip Time) is less than the expected user plane latency. Thisis due to the fact that the eNodeB periodically provides for adummy uplink allocation of 1 PRB every 7 ms. Consequently,if the uplink ping request/reply immediately preceeds theperiodical dummy uplink allocation, then the LTE UE cansend a Buffer Status Report (BSR) using the dummy uplinkallocation instead of waiting for the periodical schedulingrequest and for the eNodeB to process the scheduling request.

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This ultimately reduces the delay by 6 - 16ms (6ms for sendingscheduling request and wait for the uplink grant, and another0 - 10ms for waiting for the periodical scheduling request).

As we now discuss, there are a few cases with atypicalresults. In the execution of CC-1092U, the Near position UEexperienced nine unsuccesful pings with an average of 45msping RTT. In CC-1094U, there are 18 pings that experience along RTT (> 500ms) that increase the average RTT down to159ms. This is possibly due to the LTE UE not being able todecode the PDCCH (Physical Data Control Channel) correctly.Finally, for CC-1081U, the average RTT is 41ms, which isslightly higher than the expected 35ms. However, the rest ofthe test cases show very good results, with average RTTs lessthan the 35 ms target.

V. CONCLUSION

In this paper, we have discussed the performance of a 3GPPLTE trial network. The performance results obtained in theLTE field trial generally indicate that the 3GPP LTE Release8 can achieve excellent throughput performance over a widevariety of radio conditions for both TCP and UDP applications.The adaptive MIMO algorithm generally works as expected –yielding near peak throughputs for some of the cases underconsideration and user plane latency results show an averageRTT of less than the 35 ms target. Finally, in multi-userscenarios, we have also observed very good peak throughputperformance.

REFERENCES

[1] H. Holma and A. Toskala, LTE for UMTS - OFDMA and SC-FDMABased Radio Access, Wiley Publishers, June 2009.

[2] E. Dahlman, S. Parkvall, J. Skold and P. Berning, 3G Evolution, SecondEdition: HSPA and LTE for Mobile Broadband, Academic PressPublishers.

[3] 3GPP Technical Report, TR 25.913 version 2.1.0, ’Requirements forEvolved UTRA and UTRAN’, 3GPP TSG RAN no. 28, Quebec, Canada,June 1-3, 2005, Tdoc RP-050384.

[4] 3GPP Technical Standard, TS 36.213 v8.7.9, ’Evolved Universal Terres-trial Radio Access (E-UTRA); Physical layer procedures (Release 8)’.

[5] 3GPP Technical Report, TR 25.814, ’Physical Layer Aspects for EvolvedUTRA’, v7.0.0 (2006-06).

[6] R. Mullner, C. Ball, K. Ivanov, J. Lienhart and P. Hric, ’Contrastingopen-loop and closed-loop power control performance in UTRAN LTEuplink by UE trace analysis’, IEEE ICC 2009 Proceedings.

[7] J. M Holtzman, ’Asymptotic analysis of proportional fair algorithm,’IEEE Conf. on Personal, Indoor and Mobile Radio Communications,PIMRC, San Diego, USA, Sept. 2001.

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