Литература / UMTS-Report

A1.2.22.2 What are the number of power control cycles per second?

Depending on the required service and the deployed environment the number of power control cycles per seconds may vary between 2 and 200.

A1.2.22.3 What is the power control dynamic range in dB?

The power control dynamic range is 80 dB for mobiles and 30 dB for base stations.

A1.2.22.4 What is the minimum transmit power level with power control?

The minimum transmit power level is dependent upon the actual mobile class considered. For a 1Watt mobile the minimum transmit power level is -40dBm.

A1.2.22.5 What is the residual power variation after power control when SRTT is operating? Please provide details about the circumstances (e.g. in terms of system characteristics, environment, deployment, MSspeed, etc.) under which this residual power variation appears and which impact it has on the system performance.

The residual power variation is less than 0.3dB rms during a burst.

Characterize the diversity combining algorithm, for example, switch diversity, maximal ratio combining, equal gain combining. Additionally, provide supporting values for the number of receivers (or demodulators) per cell per mobile user. State the dB of performance improvement introduced by the use of diversity.

For the mobile station: what is the minimum number of RF receivers (or demodulators) per mobile unit and what is the minimum number of antennas per mobile unit required for the purpose of diversity reception?

These numbers should be consistent to that assumed in the link budget template in Annex 2 and that assumed in the calculation of the “capacity” defined at A1.3.1.5.

MS and BS:

∙Frequency diversity due to CDMA-spreading, and frequency hopping (based on time slots or TDMA frames, option).

∙Time diversity due to interleaving and FEC coding.

∙Interferer diversity due to CDMA-spreading, frequency hopping (option) and time slot hopping (using slots with different numbers in consecutive TDMA frames, option).

Additional diversity in BS:

∙Antenna diversity using maximal ratio pre-detection combining.

∙Space diversity using sectorized antennas (option).

MS: The number of receivers (or demodulators) is 1. The number of used antennas is 1.

BS: In case of 8 CDMA codes assigned to 8 different mobile stations the number of receivers (or demodulators) per cell and per mobile is 1/8. Hence, only 1 receiver is required for 8 mobiles.

A1.2.23.2 What is the degree of improvement expected in dB? Please also indicate the assumed condition such as BER and FER.

The gains achievable by the different types of diversity depend on the characteristics of the mobile radio channel, the interference situation, and the combination of types of diversity used in the system. The dependence on the combination means that, e.g. when introducing an addition type of diversity in a system which provides only small diversity, the gain achievable by this additional type of diversity is larger as compared with the case of introducing the same additional type of diversity in a system which already provides large diversity. Hence, diversity gain due to single features cannot be added to get overall diversity gain.

For further details confer to the simulation results (link and system level) and the paper

Klein, A.; Steiner, B.; Steil, A.: Known and novel diversity approaches as a powerful means to enhance the performance of cellular mobile radio systems. IEEE Journal on Selected Areas in Communications, Vol. 14, No. 10, pp. 1784-1795, December 1996.

A1.2.24 Handover/Automatic Radio Link Transfer (ALT) : Do the radio transmission technologies support handover?

Characterize the type of handover strategy (or strategies) which may be supported, e.g. mobile station assisted handover. Give explanations on potential advantages, e.g. possible choice of handover algorithms. Provide evidence whenever possible.

WB-TDMA/CDMA supports HO as required in SMG2 ETR (04-01). Discrimination is made between HO for real time (RT) and non-real time (NRT) services.

For RT, the basic HO scheme is similar to GSM i.e., the basic scheme is a mobile assisted, network evaluated and decided hard handover using backward signalling. Further, appropriate measures are provided to accelerate the HO procedure, e.g. in case of a corner effect

For NRT, the basic HO scheme is similar to GPRS for GSM i.e., the basic scheme is a mobile evaluated and decided (with background network control) hard handover using forward signalling (cell reselection).

Detailed description refer to part 1 of the evaluation report.

Potential advantages:

∙Seamless HO for RT, lossless HO for NRT bearer services

∙High grade of compatibility to GSM to support efficient HO between WB-TDMA/CDMA and GSM

∙Agreed bearer service is maintained during HO as far as possible; if the target cell cannot maintain the service (capacity/service offer reasons) bearer re-negotiation is performed to prevent a drop of the bearer service

∙HO applicable for different cell size (pico,micro,macro) and hierarchical cell structures

∙network evaluated handover allows high flexibility of the used HO algorithms, e.g. operator specific solutions are possible

∙‘Emergency HO’ scheme to mitigate the corner effect

HO scheme also applicable for simple MS

-the way the handover detected, initiated and executed,

-how long each of this action lasts (minimum/maximum time in msec),

-the timeout periods for these actions.

The ‘Emergency HO’ scheme is dedicated to mitigate the corner effect for RT bearer services 1.) Detection and initiation of ‘Emergency HO condition’:

∙measurement pre-processing comprises trend analysis (MS and BS)

∙Shorter HO window size in combination with higher thresholds

∙After detection of ‘Emergency HO condition’ immediate event notification in the network

2.) Decision:

∙accelerated HO decision: HO candidate cell set is reduced to ‘Emergency HO cell’ subset; this subset is predefined and known both in the network and in the MS (via broadcast information). In HCS this subset may comprise cell(s) of a super-ordinate layer

3.) Execution:

∙default HO execution procedure: HO command send to MS by the old cell using backward signalling; MS performs ‘pseudo-synchronous’ handover to ‘Emergency HO cell’

if backward signalling is no longer possible (connection loss to old BS) or if the HO command is lost (detected by timeout), the MS performs forward HO to ‘Emergency HO cell’

A1.2.25 Characterize how does the proposed SRTT react to the system deployment in terms of the evolution of coverage and capacity (e.g. necessity to add new cells and/or new carriers):

-in terms of frequency planning

-in terms of the evolution of adaptive antenna technology using mobile identity codes (e.g. sufficient number of channel sounding codes in a TDMA type of system)

-other relevant aspects

By using adaptive antennas, the coverage and capacity of WB-TDMA/CDMA can be improved significantly, cf. A1.3.6. These coverage improvements can be used to increase the cell size (range extension). Capacity improvements can be achieved by reducing the cluster size, i.e., the number of cells per cluster, or by using 16 QAM instead of the QPSK data modulation.

The cluster size may be reduced until all available frequencies are used in every cell (cluster size one). Alternatively or to increase the number of available resources even further, each cell may be sectorized, e.g., into three sectors. Furthermore, each sector may be covered by an adaptive antenna array. Different frequency groups or (alternatively) the same frequency groups may be used in different sectors of a cell. If the same frequencies are used in every sector (which provides the highest capacity), different (spreading) code families must be employed in each sector to separate the co-channel users. In this case, up to 3 x K = 24 co-channel users can be served in every cell, assuming that the cells are sectorized into three sectors.

For further information refer to A1.4.15.

A1.2.26 Sharing frequency band capabilities: To what degree is the proposal able to deal with spectrum sharing among UMTS systems as well as with all other systems:

-spectrum sharing between operators

-spectrum sharing between terrestrial and satellite UMTS systems

-spectrum sharing between UMTS and non-UMTS systems

-spectrum sharing between private and public UMTS operators

-other sharing schemes.

-The proposal is designed that within the total spectrum several operators can operate their system in an uncoordinated manner. This assumes that each of these operators have a dedicated band of operation including guard bands between operators. Due to the fact that possible sharing scenarios are not yet specified it is not easy to say how far the operators require a guard band between their systems. The definition of the RF parameters requires the set up of system scenarios to analyze the impact of MS to MS, BS to MS and MS to BS interference in different environments. By means of these scenarios, the RF limits can be defined to ensure proper operation.

-The proposal is able to co-exist with the satellite UMTS system, as far a certain guard band is kept between the carriers. The UMTS satellite systems can utilize both, a TDMA and a CDMA structure. Depending on this, the spectrum roll off is defined. Due to the fact, that the current UMTS satellite specification allows an operation of a carrier on the band edge (!), the UMTS satellite carrier pollutes into the UMTS band. This can require to keep several carriers on the band edge free. This is dependent on the local spectrum allocation and the used satellite transmission technique.

The WB-TDMA/CDMA proposal will typically require one carrier guard band, to protect a UMTS satellite system. But this has to be cross-checked with transmission parameters of the adjacent system. It has to be noted that the co-existence of UMTS and Satellite UMTS has to be treated like an in-band interference situation, due to the fact that the spectrum allocation does not provide any guard space.

- spectrum sharing between UMTS and non-UMTS systems

Here we have to distinguish between the case that the non UMTS system is allocated out of the UMTS band, and secondly inside the UMTS band.

Systems outside the UMTS band are protected by the fact, that min. guard bands can be expected between the systems. Further more both systems have to fulfill out of band spectrum requirements which are usually in line with CEPT requirements to ensure the uncoordinated operation of systems within one area. If there are insufficient guard bands allocated, system scenarios have to be used to define other measures, like the reduction of power for corner carriers. This is very much depending on the transmission technique used by the non UMTS system. The system scenarios have to be used to identify interference sources and victims. If this is analyzed special measures can be defined.

Non UMTS systems which are operated inside the UMTS band will require a certain guard band to the UMTS systems. To evaluate these guard bands, again system scenarios have to be made. This is very much depending on the transmission technique used by the non UMTS system. The system scenarios have to be used to identify interference sources and victims. If this is analyzed special measures can be defined.

- spectrum sharing between private and public operators

Private operators can be wireless PBXs running in a companies plant, and cordless type devices in residential applications. If for the private use a part of the spectrum is reserved, like the spectrum portion of a public operator, the coexistence is the same like between two public operators. I.e. the private equipment can be designed with the same RF parameters as for the public use. If the private equipment is used in the same spectrum portion of a public operator, both the public and the private systems will suffer by interference. This effect can be limited by modifying e.g. the RF parameters of the private systems by reducing TX powers to the minimum required level to maintain the link quality of the private system. Such measures will reduce the interference between private and public operation. However it will remain a capacity and performance quality degradation for both operator types. For an optimized use of the spectrum, we recommend to keep a separate spectrum for this applications.

A1.2.27 Dynamic channel allocation: Characterize the DCA schemes which may be supported and characterize their impact on system performance (e.g. in terms of adaptability to varying interference conditions, adaptability to varying traffic conditions, capability to avoid frequency planning, impact on the reuse distance, etc.)

WB-TDMA/CDMA facilitates the application of a variety of dynamic channel allocation (DCA) strategies, where the allocation of channels depends on the current traffic load and/or the current interference conditions. All bearer capabilities for UMTS outlined in ETR 04-01 are supported for the listed propagation environments (pico-, micro-, and macro-cells). To achieve maximum flexibility, the DCA algorithms treat uplink and downlink independently from each other. Of course, the MS capabilities have to be taken into account.

In general, two types of DCA can be distinguished. Allocation of carrier frequencies to cells is often referred to as slow DCA, whereas the allocation of a channel to a certain call is called fast DCA. In WB-TDMA/CDMA, a channel is characterized by its frequency, time slot, and spreading code as explained in the chapter on the physical channel structure. If frequency hopping is used, the carrier frequencies can be considered as equal from an interference point of view. The interference on different slots in the time frame, however, may still be different. Therefore, a DCA algorithm that allocates the least interfered slots to ongoing calls results in a considerable gain in quality and/or capacity. If synchronized base stations are used, advanced combinations of fast and slow DCA can be implemented.

A1.2.28 Mixed cell architecture: How well do the technologies accommodate mixed cell architectures (pico, micro and macro cells)? Does the proposal provide pico, micro and macro cell user service in a single licensed spectrum assignment, with handoff as required between them? (terrestrial component only)

Note: Cell definitions are as follows:

pico - cell hex radius (r) < 100 m micro - 100 m < (r) < 1000 m macro - (r) > 1000 m

The proposal fully supports the hierarchical cell structure with at least 3 layers. Due to the moderate bandwidth of the carrier the separation between the different layers can be easily realized on the basis of frequency sharing between layers. That means that the available frequency band has to be grouped in sub-bands of several carriers allocated each to a layer. However the borders of the sub-bands will be kept flexible and the bandwidth allocation will be managed by the slow dynamic channel allocation in order to adapt the capacity of each layer to the slow trend of the traffic in the covered area and meet the loss of trunking efficiency resulting of a fixed allocation.

In the case a limited number of cells covering a defined area is kept synchronous a layer separation on a time slot basis is also possible in this area. However this option still requires more investigations and is for further study.

A requirement of HCS is to modify the usual handover algorithms due to signal strength and quality by introducing new parameters in order to ensure a re-partition of the mobiles in the best appropriate layer from a system point of view, even if another cell in another layer is offering equal or even better radio propagation conditions. Also the controlled transition from a layer to another lower or higher hierarchical layer has to be ensured. For this aim the handover algorithms take into account the following criteria:

∙the speed of the mobile: fast moving mobiles are served in the micro or macro-cell layer.

∙the required service: very high bit rate services are expected to be served by the pico cell layer.

∙the priority and the type of each cell: As far as possible the mobile is kept in the lowest layer and handover is performed between cells belonging to the same hierarchical layer. However the assigned cell priority level offers the operator the means for a fine tuning of the traffic distribution in the network. The case of very fast signal degradation is coped by the emergency handover scheme.

A1.2.29 Describe any battery saver / intermittent reception capability

∙power control

∙discontinuous transmission (DTX) for voice and packet transmission for data

∙discontinuous reception

A1.2.29.1 Ability of the mobile station to conserve standby battery power: Please provide details about how the proposal conserve standby battery power.

∙Transmitter: During stand-by the transmitter part of the MS can be switched off completely. This is due to the TD principle, which does not require uplink power control for an MS during standby periods.

∙Receiver: For approx. 93 % of the time the receive part of the portable can be shut down. Only control channels are active in downlink direction. Within these control channels information to the MS is transmitted at certain pre-defined points in time only (similar to GSM). The receive part of a MS needs to be active for approx. 7% of the time for paging and cell broadcast messages as well as cell monitoring.

A1.3.1.3 What is the maximum tolerable delay spread (in nsec) to maintain the voice and data service quality requirements?

Note: The BER is an error floor level measured with the Doppler shift given in the BER measuring conditions of ANNEX

Up to an excess delay of about 53 500 ns

This is valid in case of the uplink if all bursts within a time slot are allocated to one and the same user or it is valid for the downlink in general.

However, for excess delays of 53 500 ns some symbols of the data symbol field following the midamble might have to be punctured in order to increase the guard interval. For more details refer to part 1 of the evaluation report.

A1.3.1.4 What is the maximum tolerable doppler shift (in Hz) to maintain the voice and data service quality requirements?

Note: The BER is an error floor level measured with the delay spread given in the BER measuring conditions of ANNEX 2.

Refer to link level simulation results in part 3 of the evaluation report.

A1.3.1.5 Capacity: The capacity of the radio transmission technology has to be evaluated assuming the deployment models described in ANNEX 2 and technical parameters from A1.2.22 through A1.2.23.2.

A1.3.1.5.1 What is the voice traffic capacity per cell (not per sector): Provide the total traffic that can be supported by a single cell in Erlangs/MHz/cell in a total available assigned non-contiguous bandwidth of 30 MHz (15 MHz forward/15 MHz reverse) for FDD mode or contiguous bandwidth of 30 MHz for TDD mode. Provide capacities considering the model for the test environment in ANNEX 2. The procedure to obtain this value in described in ANNEX 2. The capacity supported by not a standalone cell but a single cell within contiguous service area should be obtained here.

Refer to part 4 of the evaluation report.

A1.3.1.5.2 What is the information capacity per cell (not per sector): Provide the total number of user-channel information bits which can be supported by a single cell in Mbps/MHz/cell in a total available assigned non-contiguous bandwidth of 30 MHz (15 MHz forward / 15 MHz reverse) for FDD mode or contiguous bandwidth of 30 MHz for TDD mode. Provide capacities considering the model for the test environment in ANNEX 2. The procedure to obtain this value in described in ANNEX 2. The capacity supported by not a standalone cell but a single cell within contiguous service area should be obtained here.

Refer to part 4 of the evaluation report.

A1.3.1.6 Does the SRTT support sectorization? If yes, provide for each sectorization scheme and the total number of user-channel information bits which can be supported by a single site in Mbps/MHz (and the number of sectors) in a total available assigned non-contiguous bandwidth of 30 MHz (15 MHz forward/15 MHz reverse) in FDD mode or contiguous bandwidth of 30 MHz in TDD mode.

Sectorization is supported. For more details refer to part 4 of the evaluation report.

A1.3.1.7 Coverage efficiency : The coverage efficiency of the radio transmission technology has to be evaluated assuming the deployment models described in ANNEX 2.

A1.3.1.7.1 What is the base site coverage efficiency in Km2/site for the lowest traffic loading in the voice only deployment model? Lowest traffic loading means the lowest penetration case described in ANNEX 2.

The base station density represents a figure to get the minimum required number of base stations for an area. I.e. the minimum number of base stations is derived by the noise limitation of the cell, and not by interference or capacity. E.g. assume a range for a 8kbps voice service of 4.4 km (which is quite close to the values presented in the link budget calculations). To calculate the area of one sector the formula given in section 1.6.1 of 0402 is used. It is assumed that one BTS site has 3 sectors. The corresponding base station density is 0.0265 base stations per square km for this service.