Download MapBasic User Guide

Drive testing is principally applied in both the planning and optimisation stage of network development. However, there are other purposes for which drive testing can be used:

•To provide path loss data for initial site survey work
•To verify the propagation prediction during the initial planning of the network.
•To verify the network system parameters, as defined in the EG8: GSM/DCS System-Specific Parameters.
•To provide the initial test parameters used in Benchmarking (as defined in the "Analysis" section of the Network Performance and Monitoring Guideline).
•To verify the performance of the network after changes have been made e.g. When a new TRX is added; the removal or addition of a new site; any power Adjustments or changes to the antenna; any changes in clutter or traffic habits such as the addition of new roads etc.
•To measure any interference problems such as coverage from neighboring Countries.
•To locate any RF issues relating to traffic problems such as dropped or blocked calls.
•To locate any poor coverage areas.
•To monitor the network against a slow degradation over time, as well as Monitoring the network after sudden environmental conditions, such as gales or electrical storms.
•To monitor the performance of a competitor's network.
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When to Drive Test

Drive testing can take place during the day or at night and is dependant upon the
Operator's requirements and subscriber habits.
Drive testing during the day will mimic the conditions as seen by subscribers, but may
clog up the network if call analysis is being performed.
Drive testing during the night will allow a greater area to be surveyed due to the reduction
in vehicular congestion. It will also allow for certain test signals to be transmitted and tested, particularly when setting up a new site, without interrupting normal operation.
However, night-time testing does not mimic the conditions experienced by subscribers.
For planning purposes, drive testing is typically performed at night and for maintenance
purposes, drive testing is performed during the day.

Where to Drive Test

Some areas of a network will have greater performance problems than others. Drive
testing should not be uniform throughout the whole network, but should be weighted
towards areas where there are significant RF problems.
There may be other areas of the network that require temporary coverage during a certain
time of the year e.g. an exhibition centre or a sports stadium. These areas should be
examined and planned in greater detail.

It is important that a drive test is documented. This is specified by the Operator and can either take the form of creating a new item of documentation or filling in an existing document.

RSSI

The Received Signal Strength Indicator (RSSI) is a value that takes into account both RSCP and Ec/I0. It is usually given in dBm and can be calculated as follows: RSSI [dBm] = RSCP [dBm] - Ec/I0 [dB]

Ec/Io

This is the ratio of the received energy per chip (= code bit) and the interference level, usually given in dB. In case no true interference is present, the interference level is equal to the noise level.

Because of the system gain (see 1), the interference level can be higher than the wanted signal level. Therefore, at the coverage border, the value of Ec/I0 is usually negative.

RSCP

The "Received Signal Code Power" (RSCP) is the collected RF energy after the correlation / descrambling process, usually given in dBm. Only this code power is of interest for the following receiver stages when judging on the quality of the reception.

HSDPA uses link adaptation, which means the way of transmission is changed according to the quality of the channel conditions.

If a user is in favourable conditions, for example close to the nearest antenna tower, this user will be assigned a high data rate.

When the user moves into worse channel conditions, for example far away from the antenna tower, the transmission parameters will be changed accordingly and thus the data rate will be decreased.

Latency is the time a packet needs to travel from sender to receiver. While UMTS typically features an end-to-end latency of approximately 200ms, HSDPA manages to lower the delay times in transmission to around 100ms.

ARQ (Automatic Repeat Request), which is used in UMTS, a package received in error will be discarded and a retransmission will be requested. If the retransmission is also erroneous, another retransmission will be requested.

Using HARQ, an erroneous package will be stored at the receiver and a retransmission will be requested. Even if the retransmission is faulty, the receiver attempts to combine the two erroneous packages to reproduce the original package.

1)After every TTI the resources can be redistributed among the users. Therefore, the resource usage is more efficient.

2)each UE reports about the channel quality after every TTI by sending the CQI.

3)CQI is sent after the very short period of time of 2 ms, it is possible to effectively perform link adaptation even in rapidly changing conditions.

Pilot channel power or Ec is always less than the Total Cell Power, the ratio of the Pilot power (Ec) to the Total Cell power (Io) is always less than one.

Thus, when measured in Decibels,the value of Ec/Io is always negative.

Here is the calculation.

Ec = Pilot Channel Power or Effect Energy Channel
Io = Total Energy and Noise.

Ec/Io = 10.log [Pilot Channel Power / (Total Energy with Noise)] < 10.log(1) = 0

so Ec/Io always negative

The main idea in HSDPA is to use the radio resources, mainly power and code, in an optimal way, that is possible by adapting rapidly to the instantaneous radio conditions.

3 main functionalities which makes this possible are Fast Link Adaptation, Fast Hybrid ARQ (Automatic Repeat Request) and Fast Channel-dependent Scheduling.

 What are the new features that enables the high data rates and better system throughput? We shall shortly introduce them in this slide and go into details in the coming slides.

We have Short Transmission Time Interval, shorter than R99. It is only 2 milliseconds and therefore reduces the round trip time.

The main benefit from shorter TTI is the reduced delays and therefore improved end-user performance. It also makes RRM functionalities much faster.

 Then we have Shared Channel Transmission. One HS dedicated channel shared dynamically by all HSDPA users , mainly in the time domain.

That results in system capacity gain.

Fast Scheduling gives priority to the users with favorable radio conditions. This is also something which contributes to system capacity.

Fast link adaptation gives maximum channel utilization because data rate is adapted to radio conditions. Higher order modulation gives higher data rates.

And finally, Fast retransmissions together with soft combining leads to better end-user performance and capacity increase.

HSDPA is an improvement of  best-effort packet data on the DL in WCDMA in terms of speed, capacity and end user performance.

Higher bit rates up to 14 Mbps and system throughput which is 2-3 times higher than WCDMA Release 99.

End user performance is also improved by means of reduced Round Trip time  and higher bit rates.

HSDPA is standardized. The current WCDMA is extended by HSDPA in Release 5 of 3GPP specifications. Mainly,  a new DL transport channel is introduced that enhances support for interactive, background and, to some extent, streaming services and some powerful RRM functionality is introduced.

In a WCDMA network, it is possible not to upgrade all cells with HSDPA functionality since we have mobility between HSDPA and non HSDPA cells.

 We don’t need a separate carrier for HSDPA. Voice and data on the same.

We have simultaneous use of high speed packet data bearers and conversational bearers.

The basic RAN architecture supports HSDPA. The only need is to have some additional HW in RBS and additional SW for both RBS, RNC and RXI nodes.

All of these make a smooth and cost-efficient upgrade to HSDPA possible.  

HSPA supports 16QAM modulation on the downlink and QPSK on the
uplink. As Figure 4 shows, the data capacity (bits/symbol) increases as
we move from QPSK to 16QAM and 64QAM. HSPA+ R7 introduces
64QAM on the downlink, which increases the data rates by 50% for
devices in good signal conditions (high SNR). On the uplink, 16QAM
doubles data rates for devices that are not power headroom limited.

Wireless signals transmitted with a higher modulation are more sensitive
to interference and require a higher SNR at the receiver for successful
demodulation. HOM significantly increases the data rates for users with
high SNR. Hence, the traffic for these users can be serviced faster,
leaving Node B with more time and resources to service users in weaker
signal areas, such as the cell edge. Overall, this provides high data rates
and improved user experience for all users in the cell.

HSPA+ R7 supports 2x2 downlink MIMO that uses two transmit
antennas at the Node B to transmit orthogonal (parallel) data streams to
the two receive antennas at the device. Using two antennas and
additional signal processing at the receiver and the transmitter, MIMO
can increase the system capacity and double user data rates without
using additional Node B power or bandwidth. Additionally, MIMO
beamforming provides gains for cell edge users where parallel MIMO
streams may not be possible.

To be most effective, parallel MIMO streams need a high signal-to-noise
ratio (SNR) at the device and a rich scattering environment. High SNR
ensures that the device will be able to decode the signal successfully
and a rich scattering environment ensures that the two data streams
remain orthogonal. The MIMO benefit is therefore maximized in a dense
urban (city) environment, as there is enough scattering and cell sizes are
small (potentially high SNR at the device). In rural environments with
large cell sizes and less scattering, the MIMO gains will be smaller.

With the launch of HSPA, operators are seeing a significant uptake in
data demand, a result of new data applications and increased demand
for high-performance mobile broadband services. HSPA+ enhances the
performance of HSPA networks and enables wireless operators to
continue to fulfill these data needs in the most economical way, as
HSPA+ doubles the data capacity compared to HSPA R6.



HSPA greatly increased data capacity over R99 systems by adding the
high-speed shared channels with HOM (16QAM), smaller transmission
interval, Hybrid ARQ (HARQ) and opportunistic scheduling. HSPA+
builds on this solid foundation by adding support for 64QAM, 2x2 MIMO,
DTX/DRX and other air interface improvements to enhance the capacity
and the user experience.

HSPA and HSPA+ allows consumers and business users to rely on HSPA as their main broadband connection, and offer a similar user experience across mobile and fixed networks.

HSPA’s high-capacity broadband uplink and downlink with integrated QoS and low latency can support the entire range of IP services, including delay-sensitive
applications such as VoIP and low latency gaming.

HSPA+ further enhances the user’s experience and makes these services more affordable by lowering costs through increased capacity.

HSPA+ is the name of the set of HSPA enhancements that are defined in 3GPP beyond Release 6 (R6). The enhanced downlink (HSDPA) was defined in R5 and the enhanced uplink (HSUPA) was defined in R6.

HSPA+ has a strong evolution path and will continue to evolve beyond HSPA+ R8 to further enhance the HSPA+ performance and provide a clear evolution path for current HSPA networks. The definition of HSPA+ R9 was already initiated in early 2009. HSPA+ R9 and beyond is considering enhancements such as expanding HSPA+ multicarrier
beyond 10 MHz deployments combined with MIMO (Multiple Input Multiple Output) to provide peak rates of 84 Mbps and more.

Nearly all WCDMA operators across both developed and developing countries have rapidly launched HSPA services to capitalize on its excellent mobile broadband capabilities and increased data capacity. The enhanced downlink (HSDPA) had been launched commercially by 217 operators in 93 countries as of early 2009.

The enhanced uplink (HSUPA) is also quickly being introduced with around 50 deployments as of early 2009. HSPA devices have proliferated and mobile operators
have seen data services account for a rising and substantive proportion of their revenue. HSPA+ is the natural evolution of HSPA and operators are now preparing to commercially launch HSPA+ R7 in early 2009.

HSPA+ R7 is the first evolutionary step beyond HSPA and HSPA+ R8 is targeted for commercialization during 2010 with multicarrier as a key feature. HSPA+ further enhances the mobile broadband experience and increases the voice and data capacity of HSPA. This white paper discusses the HSPA+ key benefits:

HSPA+ enhances mobile broadband with data rates up to 42 Mbps in R8 while R7 enables up to 28 Mbps downlink data rates.

HSPA+ doubles the data capacity over HSPA and more than doubles voice capacity over WCDMA, reducing the cost of delivering voice or data services (more efficient voice over HSPA+ can also be used to free up data capacity).

HSPA+ enhances the end-user experience with lower latency, faster call set-up time, improved “always-on” experience and a longer talk time.

HSPA+ multicarrier further enhances the broadband experience.

HSPA+ R8 doubles the data rates to all users and can significantly increase the bursty application capacity, e.g., Web browsing.

HSPA+ is the optimal solution for single and aggregated 5 MHz carriers, and provides similar performance as LTE for the same bandwidth and using the same number of antennas.

HSPA+ is the natural evolution of HSPA at a lower cost, enabling an incremental and cost-effective upgrade that leverages existing assets.