CDMA2000™

StandardizationCDMA2000 is the third generation (3G) solution based on IS-95 — more commonly known as cdmaOne. CDMA2000 is an evolution of the 2G wireless standard. CDMA2000 supports 3G services as defined by the International Telecommunications Union (ITU) for IMT-2000. 3G networks will deliver wireless services with better performance, greater cost-effectiveness and significantly more content and CDMA2000 technology satisfies those goals.

Both cdmaOne and CDMA2000 systems are based on spread spectrum multiple-access technology that has rapidly gained global acceptance by wireless operators. cdmaOne and CDMA2000 networks spread coded conversations and data transfers over 1.25 MHz of spectrum, allowing a large number of users to simultaneously share the same carrier.

CDMA2000 is one solution for wireless operators who want to take advantage of the new market dynamics created by mobility and the Internet. It is both an air interface and a core network solution for delivering the services that customers are demanding today - sometimes referred to as 3G services.

CDMA2000 is one mode of the Radio Access "family" of air interfaces agreed upon by the Operators Harmonization Group for promoting and facilitating convergence of 3G networks. One goal of the harmonization effort is to provide seamless global roaming between the two different modes of 3G CDMA - CDMA2000 and WCDMA. Ericsson's use of common core technologies allows easy support of the whole family of 3G CDMA modes.

Ericsson's CDMA Systems business unit in San Diego is developing CDMA2000-capable 3G infrastructure products. Ericsson's CDMA2000 portfolio is designed to mitigate risks, protect investments and deliver significant performance boosts to operators as they evolve their networks to offer 3G services. CDMA2000 networks are backwards-compatible to cdmaOne deployments, protecting operator investments in cdmaOne networks and providing simple and cost-effective migration paths to the next generation. This means that both cdmaOne terminals and CDMA2000 terminals can operate in coverage areas of either network. In addition to offering voice quality and voice capacity improvements, CDMA2000 networks support high-speed, multimedia data services. Data Support The CDMA2000 standard is evolving to continually support new services in a standard 1.25 MHz carrier. The first phase of CDMA2000 - or CDMA2000 1X - will deliver peak data rates of 153 kbps. Phase two - labeled CDMA2000 1xEV - will provide for data rates greater than 2 Mbps.CDMA2000 1X The IS-2000 standard (CDMA2000 1X) was completed in 2000 and published by the Telecommunications Industry Association (TIA). CDMA2000 1X offers approximately twice the voice capacity of cdmaOne, peak data rates of 153 kbps, backwards compatibility with cdmaOne networks and many other performance improvements. 1X refers to CDMA2000 implementation within existing spectrum allocations for 1.25 MHz carriers. The technical term is derived from N=1 (i.e., use of same 1.25 MHz carrier as in 2G) and the 1X means one times 1.25 MHz.

CDMA2000 1X can be implemented in existing spectrum or in new spectrum allocations. A CDMA2000 1X network

will also introduce simultaneous voice and data services and other performance improvements. The backwards compatibility with cdmaOne provided by Ericsson's CDMA2000 solution, further ensures investment protection.

CDMA2000 1xEV The evolution of CDMA2000 beyond 1X is now labeled CDMA2000 1xEV. 1xEV will be divided into two steps: 1xEV-DO and 1xEV-DV. 1xEV-DO stands for 1X Evolution Data Only. 1xEV-DV stands for 1X Evolution Data and Voice. Both 1xEV evolution steps provide for advanced services in CDMA2000 using a standard 1.25 MHz carrier.

Evolution with CDMA2000 will therefore continue to be backwards-compatible with today's networks and forwards-compatible with each evolution option. 1xEV-DO will provide for higher data rates on 1X systems. 1xEV-DO will require a separate carrier for data, but this carrier will be able to handoff to a 1X carrier if simultaneous voice and data services are needed. By allocating a separate carrier for data, operators will be able to deliver peak rates in excess of 2 Mbps (best effort) to their data customers. 1xEV-DV solutions will be available approximately one and a half to two years after 1xEV-DO. 1xEV-DV will bring data and voice services for CDMA2000 back into one carrier. A 1xEV-DV carrier will provide not only high-speed data and voice simultaneously, but will also be capable of delivering real-time packet services.

CDMA2000 Packet Core Network The standards for a CDMA Packet Core Network (PCN) were developed as part of the Third Generation Partnership Project 2 (3GPP2) working groups. These standards were developed by using existing standards from the IETF (Internet Engineering Task Force) on Mobile IP. 3GPP2 is also busy defining the evolution of a CDMA2000 network to All-IP. The CDMA2000 PCN is the first step in this evolution.

To provide secure and efficient transport for wireless data, Ericsson has introduced a data delivery mechanism using the PCN. The PCN network is comprised of the Packet Data Serving Node (PDSN) and the Authentication, Authorization and Accounting server (AAA). The Home Agent (HA) can be added to provide Mobile IP-based packet data services. For more information about Ericsson CDMA2000 products

Product and Service Solutions that Deliver the Full Advantage of CDMA Technology Leveraging proven leadership in mobile networks and packet switching, the CDMA2000 product portfolio is built on Ericsson's 3G global platform technology. By combining industry-leading compact radio access and circuit-switched core network products with the flexible and advanced packet-switching capabilities of the CDMA2000 Packet Core Network, Ericsson assures operators of a cost-effective, future-proof solution to meet today's wireless needs and tomorrow's emerging markets.

Radio Access NetworkEricsson's CDMA2000 1X Radio Access Network (RAN) provides a comprehensive solution for mobile network operators, offering state-of-the-art Radio Base Stations (RBS) and Base Station Controllers (BSC), operational efficiencies and a smooth evolution to next-generation technologies

Packet-Switched Core NetworkBy combining a Wireless LAN Serving Node (WSN) to the flexible and advanced packet-switching capabilities of the CDMA2000 Packet Core Network (PCN) - comprised of the PDSN and HA nodes - Ericsson assures operators of always best-connected functionality and direct access to IP-service networks.

Circuit-Switched Core NetworkDesigned to provide switching and gateway functionality for voice users, the Circuit-Switched Core Network (CSCN) consists of the AXE 10 and the AXE 810 MSC.

Service NetworkThe Service Network consists of service enablers such as the Home Location Register, the Authentication Center, the Authentication, Authorization and Accounting server, the Mobile Internet Enabling Proxy and service applications such as PrePaid Calling, Messaging Over IP and Enhanced Voice Mail.

Handoff Process

In the following example, we examine the handoff process from the source cell to the target cell. As Figure 4.18 shows, the mobile is moving from the coverage area of source cell A to the coverage area of target cell B. The following is a sequence of events during this transition:1. The mobile here is being served by cell A only, and its active set con-tains only pilot A. The mobile measures pilot B E c /I 0 and finds it to be greater than T_ADD. The mobile sends a pilot strength measure-ment messageand moves pilot B from the neighbor set to the candi-date set.2. The mobile receives a handoff direction message from cell A. The mes-sage directs the mobile to start communicating on a new traffic channel with cell B; the message contains the PN offset of cell B and the Walsh code of the newly assigned traffic channel.3. The mobile moves pilot B from the candidate set to the active set. After acquiring the forward traffic channel specified in the handoff direction message, the mobile sends a handoff completion message. Now the active set contains two pilots.4. The mobile detects that pilot A has now dropped below T_DROP.The mobile starts the drop timer.5. The drop timer reaches T_TDROP. The mobile sends a pilot strength measurement message.6. The mobile receives a handoff direction message. The message contains only the PN offset of cell B. The PN offset of cell A is not included in the message.7. The mobile moves pilot A from the active set to the neighbor set, and it sends a handoff completion message.There is another mechanism that can trigger the transmission of a pilot strength measurement message by the mobile. If the strength of a pilot in the can-didate set exceeds the strength of a pilot in the active set by the active set versus

Figure The handoff process. After [1].

WCDMA Link Budget

Link budget planning is part of the network planning process, which helps to dimension the required coverage, capacity and quality of service requirement in the network. UMTS WCDMA macro cell coverage is uplink limited, because mobiles power level is limited to (voice terminal 125mW). Downlink direction limits the available capacity of the cell, as BTS transmission power (typically 20-40W) has to be divided to all users. In a network environment both coverage and capacity are interlinked by interference. So by improving one side of the equation would decrease the other side. System is loosely balanced by design. The object of the link budget design is to calculate maximum cell size under given criteria:

Type of service (data type and speed) Type of environment (terrain, building penetration) Behavior and type of mobile (speed, max power level) System configuration (BTS antennas, BTS power, cable losses, handover gain) Required coverage probability Financial and economical factors (use of more expensive and better quality equipment or

not the cheapest installation method)

and to match all of those to the required system coverage, capacity and quality needs with each area and service.

In an urban area, capacity will be the limiting factor, so inner city cells will be dimensioned by required Erlangs/km2 for voice and data. Even using 25dB as inbuilding penetration loss into the building core area, link budget would typically allow about 300m cell range, which is a way too much for a capacity purposes. In a rural area uplink power budget will determine the maximum cell range, when typically cells are less congested. A typical cell range in rural areas will be several kilometers depending on a terrain.

Below is an example of how WCDMA voice call link budget can be done. Some of the values can be debated, including the propagation model, but it gives an idea of the calculation methods.

UMTS link budget

UMTS Handover

There are following categories of handover (also referred to as handoff):

Hard Handover

Hard handover means that all the old radio links in the UE are removed before the new radio links are established. Hard handover can be seamless or non-seamless. Seamless hard handover means that the handover is not perceptible to the user. In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover.

Soft Handover

Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN. Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time. Normally soft handover can be used when cells operated on the same frequency are changed.

Softer handover

Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (i.e. the site of co-located base stations from which several sector-cells are served. In softer handover, macro diversity with maximum ratio combining can be performed in the Node B, whereas generally in soft handover on the downlink, macro diversity with selection combining is applied.

Generally we can distinguish between intra-cell handover and inter-cell handover. For UMTS the following types of handover are specified:

Handover 3G -3G (i.e. between UMTS and other 3G systems) FDD soft/softer handover FDD inter-frequency hard handover FDD/TDD handover (change of cell) TDD/FDD handover (change of cell) TDD/TDD handover Handover 3G - 2G (e.g. handover to GSM) Handover 2G - 3G (e.g. handover from GSM)

The most obvious cause for performing a handover is that due to its movement a user can be served in another cell more efficiently (like less power emission, less interference). It may however also be performed for other reasons such as system load control.

Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (i.e., the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set).

Cells, which are not included in the active set, but are included in the CELL_INFO_LIST belong to the Monitored Set.

Cells detected by the UE, which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set. Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state.

The different types of air interface measurements are: Intra-frequency measurements: measurements on downlink physical channels at the

same frequency as the active set. A measurement object corresponds to one cell. Inter-frequency measurements: measurements on downlink physical channels at

frequencies that differ from the frequency of the active set. A measurement object corresponds to one cell.

Inter-RAT measurements: measurements on downlink physical channels belonging to another radio access technology than UTRAN, e.g. GSM. A measurement object corresponds to one cell.

Traffic volume measurements: measurements on uplink traffic volume. A measurement object corresponds to one cell.

Quality measurements: Measurements of downlink quality parameters, e.g. downlink transport block error rate. A measurement object corresponds to one transport channel in case of BLER. A measurement object corresponds to one timeslot in case of SIR (TDD only).

UE-internal measurements: Measurements of UE transmission power and UE received signal level.

UE positioning measurements: Measurements of UE position. The UE supports a number of measurements running in parallel. The UE also supports that each measurement is controlled and reported independently of every other measurement.

CDMA2000 Network Optimization Fundamentals

Salam…In this post, I wanna share with you about CDMA2000 Optimization Procedure. Hope you’ll enjoy it! ^_^Wireless network Optimization can be devided in to three layers:

Device Layer Network Layer Resource Utilization Layer

We can conduct some methods to examine problems on those layers, i.e.,

Drive tests and Analysis Signaling Tracking OMC analysis Synthesis

Let’s we go in to deep to each layer above,

1. Device Layer o Antenna and Feeder Cable Fault o Transmission Fault o GPS Fault o Wireless Configuration o Office Direction Problem o Termination Problem

2. Network Layer

o Solving Dropped Call Problem with Drive Test and Analysis Method o Solving Problem with OMC Analysis Method o Improving Coverage with Synthess Method

3. Resource Utilization Layer o Network Block Optimization

4.  

CDMA Performance IndicatorsRF Performance indicators captured by drive-test activity. It show the CDMA RF environment to guide Optimization and Troubleshooting in air interface. Some parameters indicate uplink conditions, some downlink, and some both. These parameters collected at the subscriber side, so it’s easy to capture using commercial handset equipment without BSC’s assist.Basic knowledge about CDMA spread spectrum signal characteristics such as: channel definitions, power control system, call processing flow, signal behaviour in noise and interference, and RF units ( transmitter and receiver) are needed, to analyse the parameters below.

FER (Frame Error Rate) -> an excellent call quality summay statistic, it’s the end result of the whole transmission link

o reverse channel -> realized on the Base Station o forward channel -> realized at handset o if FER is good, any other problems aren’t having much effect o if FER is bad, we have to check other indicators to analyze the network problem,

because FER is just the end-result of the problem Mobile Receiver Power (Rx)-> Received Power at the handset (dBm). It should be noted

that Received Power is Important, but it’s exact value isn’t critical. o High Rx value (-35 dBm or higher) could cause overload condition in Amplifier

sensitivity, intermod and code distortion on received CDMA signals. o Low Rx value (-105 dBm or weaker would leave too much noise in the signal

after de-spreading, resulting symbol errors, bit errors, bad FER and other problems.

Ec/Io -> We can’t just use the handset’s power level to guide handoffs because it represents the total power measurement from all sectors reaching the handset. To measure the the signal level of each sector individually, we have to use each sector’s pilot (Walsh 0) as a test signal to guide handoffs.

o Ec/Io is a parameter, represents pilot cleannesses. o foretells the readability of the associated traffic channels to guide soft handoffs

decision o derived from: ratio of good to bad energy seen by search correlator at the desired

PN offset -> Ec/Io(forward) = Pilot Energy / (Paging + Synch + Traffic) Energy. Can be degraded by strong RF from other Cells, Sectors (imperfect PN orthogonality could cause -20 dB degradation) and also by noise.

o in Light condition (without traffic) Ec/Io = 3 dB, in Heavy loaded Ec/Io = -7 dB o in a clean Situation which theres a sector dominant, Ec/Io just as good as it was

when transmitted. But in “Pilot Pollution” condition, mobile hears a ’soup’ made up of all the overlapped sectors signal. So Io is the sum of all the signal received

by MS, and Eo is the energy of desired sector’s Pilot signal. The Large Io will overrides the weak Ec -> Ec/Io is too Low!

Handset Transmitter power (TxPO) o TxPO is the actual RF power output of the handset transmitter(max= 23 dBm),

including combined of open loop power control and closed loop power control (TxGA)

o this is the simple formula : TxPO = -(Rx dBm) - C + TxGA ( C= +73 for 800 MHz systems, and C=+76 for 1900 MHz systems) to reach balance link.

Sumber : http://pram.web.id/blog/2008/03/31/cdma2000-network-optimization-fundamentals