Voice services over Adaptive Multi-user Channels on One Slot

(VAMOS)

Abdullah Saleh

The feature VAMOS is specified in 3GPP release 9.VAMOS assign the same GSM physical channel (ARFCN-TDMA frame number-Time Slot) into two users simultaneously.

The GSM channel could be: Full Rate Channel Two Half Rate Channels Two VAMOS Full Rate Channels Four VAMOS Half Rate Channels One Half Rate Channel and Two VAMOS Half Rate Channels One VAMOS Full Rate Channel and Two VAMOS Half Rate Channels.

VAMOS Advantages: Doubling of voice calls per transceiver Increased call capacity per transceiver gives operators an efficient means to handle voice traffic growth in their networks without adding more TRXs.Avoiding additional TRX’s results in savings in BTS HW investments, energyconsumption and BTS foot print. Free up capacity for EDGE data servicesVAMOS reduces the number of time slots needed for voice services. This allows more time slots to be allocated for EDGE services.Note: EDGE can carry a bandwidth up to 236.8 Kbit/s for 4 timeslots (theoretical maximum is 473.6 Kbit/s for 8 timeslots) in packet mode. Free up spectrum for new technologiesFor example UMTS900 (reframing 25 GSM 200 KHz frequency channel into 5 MHz UMTS Carrier) or LTE which allow for flexible operations in different spectrum bands.

VAMOS Disadvantage: The parallel signal transmission of the two multiplexed users, causes interference

for one another, affecting speech quality if not properly controlled.

Call Drop Rate increased due to multiplexing of different MSs types.

How VAMOS Can Differentiate between two users?VAMOS transmits the combination of two signals at the same time over the same channel, each with a different orthogonal TSC’s (Training Sequence Code). Each of the two MSs that receive the data stream at the same time use their knowledge of their individual TSC to reconstruct their own part of the signal, effectively filtering away the second data stream as noise. Up-Link Operation:Transmitter (MS): use the existing GMSK modulation scheme. In other words, no new transmitter elements are required in mobile devices. Receiver (BTS): different receiver algorithms may be used, that is Space TimeInterference Rejection Combining (STIRC), Successive Interference Cancellation (SIC) or Joint Detection (JD) to receive both orthogonal sub-channels distinguished by their individual training sequences. Another option is to use two independent GMSK receivers for each sub-channel.

Down-Link Operation:Transmitter (BTS): use AQPSK modulation technique to be able to transmit two calls at the same time.Receiver (MS): use 3GPP Downlink Advanced Receiver Performance (DARP) which is also known as Single Antenna Interference Cancellation (SAIC) algorithm to correctly demodulate downlink Signal.

Transmission and reception by MS and BTS in VAMOS

Training Sequences

The training sequence code (TSC) or Channel Sounding Bits is a known 26-bit pattern placed in the middle of normal burst. TSC has eight fixed formats, which are represented by TSC ranged 0:7 respectively. The eight sequences are stored in all MS receivers to be used for Bit Synchronization and for Channel Estimation.

Because of TSC at the middle of time slot it also called Midamble. By having TSC there, the chances are better that the channel is not too different when it affects the training sequence compared to when the information bits were affected. If TSC was at the start of a burst, the channel might have changed by the end of the burst. And the same thing if it was at the end.

If MS have read SCH, it must get the TSC (Training Sequent Code) to correctly read the information on the downlink common signaling channel. TSC number is linked to the Base Station Color Code (BCC) of the cell. So one of the functions of BSIC is to inform MS of the TSC adopted by the common signaling channel of the cell.

Use of Training sequence in Equalizers:

As the information will be distorted due to time dispersion problem in air interface, the TSC will be distorted too.

The channel estimator correlate the stored TSC with the received TSC to estimate the channel impulse response.

The signal generator generates versions of all possible data sequences that could come from the transmitter.

The generated signal then pass to a channel model which is a simulation of air interface to calculate the expected received data of the estimated transmitting data.

The Viterbi algorithm will compare the actually received data with the output of channel model, if the received distorted data has matched the simulated distorted received data, then the locally generated data is the same as the data that was actually transmitted. And if not the process will repeated with different signal generator sequence of data.

DemultiplexingReceived

Data

Training Sequence Code

Channel Estimator

Information

Signal Generator

Viterbi Algorithm

Correct Data

Channel Model

Viterbi Equalizer

Use of Training sequence in VAMOS:TSCs should preferably be orthogonal to each other to guarantee the quality of the channel estimates. As cross-correlation properties of the existing (legacy) eight TSCs are not ideal, this leads to additional

interference experienced by the MS. The legacy TSC set is referred to as “TSC set 1”. In order to improve the correlation properties a new improved set of training sequences “TSC set 2”

was specified. The new set of training sequences has been found based on computational simulation work in order to obtain the best possible result with respect to cross correlation properties between existing and new training sequences.

When using “TSC set 1” the TSC must exhibit low cross-correlation and good auto-correlation in the presence of the other sub channel.

When using “TSC set 2” the multiplexing is done by taking two TSC with the same index in both sets.

TSC Training sequence bits for TSC Set 1 Training sequence bits for TSC Set 20 (0,0,1,0,0,1,0,1,1,1,0,0,0,0,1,0,0,0,1,0,0,1,0,1,1,1) (0,1,1,0,0,0,1,0,0,0,1,0,0,1,0,0,1,1,1,1,0,1,0,1,1,1)1 (0,0,1,0,1,1,0,1,1,1,0,1,1,1,1,0,0,0,1,0,1,1,0,1,1,1) (0,1,0,1,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1,1,1,0,0,0,0,1)

2 (0,1,0,0,0,0,1,1,1,0,1,1,1,0,1,0,0,1,0,0,0,0,1,1,1,0) (0,1,0,0,0,0,0,1,0,1,1,0,0,0,1,1,1,0,1,1,1,0,1,1,0,0)

3 (0,1,0,0,0,1,1,1,1,0,1,1,0,1,0,0,0,1,0,0,0,1,1,1,1,0) (0,0,1,0,1,1,0,1,1,1,0,1,1,1,0,0,1,1,1,1,0,1,0,0,0,0)

4 (0,0,0,1,1,0,1,0,1,1,1,0,0,1,0,0,0,0,0,1,1,0,1,0,1,1) (0,1,1,1,0,1,0,0,1,1,1,1,0,1,0,0,1,1,1,0,1,1,1,1,1,0)

5 (0,1,0,0,1,1,1,0,1,0,1,1,0,0,0,0,0,1,0,0,1,1,1,0,1,0) (0,1,0,0,0,0,0,1,0,0,1,1,0,1,0,1,0,0,1,1,1,1,0,0,1,1)

6 (1,0,1,0,0,1,1,1,1,1,0,1,1,0,0,0,1,0,1,0,0,1,1,1,1,1) (0,0,0,1,0,0,0,0,1,1,0,1,0,0,0,0,1,1,0,1,1,1,0,1,0,1)

7 (1,1,1,0,1,1,1,1,0,0,0,1,0,0,1,0,1,1,1,0,1,1,1,1,0,0) (0,1,0,0,0,1,0,1,1,1,0,0,1,1,1,1,1,1,0,0,1,0,1,0,0,1)

The correlation properties of GSM training sequences (values in dB)

Colored Pairs are Huawei combination

TSC Set 1

0 1 2 3 4 5 6 7

TSCSet 1

0 0.00 −5.97 −26.42 −19.39 −15.11 −15.38 −7.47 −25.39

1 −5.98 0.00 −20.76 −28.88 −21.05 −22.31 −9.45 −18.19

2 −26.42 −19.39 0.00 −5.97 −23.00 −9.21 −23.02 −20.39

3 −20.76 −28.88 −5.98 0.00 −28.42 −4.37 −15.78 −17.04

4 −14.65 −18.04 −20.03 −30.47 0.00 −12.29 −12.02 −6.59

5 −17.71 −23.46 −10.11 −4.60 −11.14 0.00 −23.18 −10.97

6 −6.86 −8.61 −17.21 −13.79 −9.80 −28.95 0.00 −10.46

7 −17.46 −13.04 −19.67 −15.61 −6.31 −10.67 −10.89 0.00

The correlation properties of GSM and new training sequences (values in dB)

TSC Set 1

0 1 2 3 4 5 6 7

TSC Set 2

0 −24.90 −10.92 −18.12 −16.15 −23.97 −21.44 −28.73 −21.21

1 −9.16 −25.94 −12.13 −7.05 −16.61 −24.81 −20.71 −17.23

2 −18.12 −16.15 −24.90 −10.92 −15.00 −14.36 −17.51 −18.83

3 −12.13 −7.05 −9.16 −25.94 −8.59 −14.37 −25.82 −21.11

4 −21.56 −19.03 −25.29 −12.22 −27.21 −24.23 −15.64 −14.80

5 −22.07 −20.62 −8.46 −18.02 −11.07 −24.99 −19.21 −14.76

6 −23.73 −21.67 −15.44 −8.48 −12.95 −12.24 −28.82 −28.74

7 −22.44 −22.73 −22.40 −20.36 −16.72 −15.44 −18.45 −24.25

Adaptive QPSK (AQPSK) ModulationIn 1986 P. Laurent showed that Gaussian Minimum Shift Keying (GMSK) phase modulation could be approximated by a Binary Phase Shift Keying amplitude modulated pulse.VAMOS extends Laurent’s approximation method to represent the superposition of two GMSK signals as a single AQPSK modulated signal.

Baseband transmitter block diagram for VAMOS AQPSK

The data from User A and User B are mapped onto QPSK constellations where for each constellation symbol, the first bit is assigned to User A, in the in-phase (I) sub-channel, and the second bit is assigned to User B, in the quadrature (Q) sub-channel.

The value of α can range between 0 and π/2, these limits representing the BPSK signal constellation points, that is either suppressing the second sub-channel (OSC B) on the Q branch (α = 0) or the first sub-channel (OSC A) on the I branch (α = π/2). The α value may be changed on a burst-by-burst basis according to the requirements for power assignment to both sub-channels. The power assignment is based on a continuous α range, but can be set discretely by the network.

Two examples of the AQPSK constellation. The sub-channel power distribution isillustrated by the length of the colored vectors

Symbol Rotation:The modulating symbols are continuously rotated with radians per symbol to avoid transitions through the origin (ensure that the envelope of the signal does not go instantaneously close to zero ). This minimizes the variations in the modulating signal which in turn minimizes the linearity requirements of the amplifier.(i.e. each phase modulated symbol is additionally phase shifted by radians per symbol).

Symbol rotation depending on modulation

AQPSK use π/2 symbol rotation to imitate GMSK, so legacy GMSK SAIC handsets can receive them separately.

Pulse Shaping:The process of changing the waveform of transmitted pulses. Its purpose is to make the transmitted signal better suited to its purpose or the communication channel, typically by limiting the effective bandwidth of the transmission. By filtering the transmitted pulses this way, the inter-symbol interference caused by the channel can be kept in control. In RF communication, pulse shaping is essential for making the signal fit in its frequency band.

Modulation QPSK 8PSK 16QAM 32QAM AQPSK

3/8 3/4 /4 -/4 /2

VAMOS DL Power ControlVAMOS Sub-channel Power Control feature adapts the AQPSK modulation constellation to distribute the downlink transmit power between the two sub-channels of the AQPSK modulated carrier. Extra power can be distributed to one of the sub-channels, at the expense of the paired sub-channel. This mechanism is important since it allows legacy mobiles to operate in VAMOS mode.

The position of the AQPSK symbols, and thus the power distribution between the sub-channels, defined by the Sub-channel Power Imbalance Ratio (SCPIR), are controlled by the VAMOS Sub-channel Power Control.

Power Control in downlink for VAMOS is done in two successive stages: Determination of the required transmit power levels for both mobile stations MS-A andMS-B according to the radio link measurement reports (RXLEV and RXQUAL) received from these mobiles. The BSS determines the power level P MSA required for MS-A in the first sub-channel and P MSB for MS-B in the second sub-channel.

Determination of the corresponding AQPSK signal constellation and output power for theAQPSK signal. A control unit in the BTS computes a combination of output power P andα that gives the required combination of P MSA and P MSB in downlink based on thefollowing relationship: P = P MSA + P MSB = P × cos2 α + P × sin2 α

Exemplary implementation of power control in downlink for VAMOS

VAMOS MS Categories:For several years now, many mobiles have been equipped with SAIC receivers to improve their resistance against inter-cell interference, i.e. not even with VAMOS in mind. In other words, when VAMOS gets deployed one does not have to wait for special VAMOS capable devices to reach a critical mass before the benefits can be seen. However terminals that support VAMOS feature increase performance of the BSS VAMOS feature.Legacy Non-SAIC:Don’t support SAIC algorithm or TSC Set 2Can’t be paired with a legacy non-SAIC MS or legacy SAIC MS.May be multiplexed on the VAMOS sub-channel in the case of much power offset.Legacy SAIC:Support SAIC algorithm but not support TSC Set 2Does not require much power offset.VAMOS level I:Support SAIC algorithm and TSC Set 2VAMOS level II:VAMOS II user devices must cope with strong negative SCIPR values, which will likelyrequire implementation of joint detection techniques in the receiver. Therefore VAMOSI and II requirements will differ by verifying voice performance at different SCPIR proofpoints. VAMOS I user devices will be tested at SCPIR = -4dB, 0dB and 4dB, whereasVAMOS II user devices will need to fulfill reference performance additionally at SCPIR= -8dB and SCPIR = -10dB.

The VAMOS-aware mobiles are expected to be served on the weaker sub-channels whenbeing multiplexed with legacy mobiles.Sub-channel Power Imbalance Ratio (SCPIR) is define by;

SCPIR[dB] = 10 × () = 10 = 20 ()assuming that MS-B receives the quadrature component and MS-A the in-phase component of the AQPSK signal.

Discrete α values with operating ranges for Different MSs

Gaussian Minimum Shift Keying Modulation (GMSK)GMSK is a continuous-phase frequency-shift keying modulation scheme. It is similar to standard minimum-shift keying (MSK); however the digital data stream is first shaped with a Gaussian filter before being applied to a frequency modulator. This has the advantage of reducing sideband power, which in turn reduces out-of-band interference between signal carriers in adjacent frequency channels.

There are two commonly used methods to generate GMSK;

1- Frequency shift keyed modulation

,but this is not suitable for coherent demodulation due to component tolerance problems.

2- Quadrature phase shift keyed modulation:

The steps followed in the modulator are as: Create the NRZ (-1,1) sequence from the binary (0,1) input sequence. Create N samples per symbols. Integrate the NRZ sequence. Convolute with a Gaussian function then compute the corresponding I and Q

components (at this stage, we have the quadrature components of the baseband GMSK equivalent signal).

Multiply the I and Q components by the corresponding Cos(nt) and Sin(nt) carriers. Add the two signals

Single Antenna Interference Cancellation (SAIC)SAIC techniques can considerably improve the receiver performance with minimum software upgrade in a communications device. SAIC was introduced by 3GPP in Release 6.

Advantages of using the SAIC technique: Requires one antenna only, so, easier to fit into a mobile. For a given number of mobile terminals in a network, SAIC mobile terminals experience

more user satisfaction in terms of frame error rate than conventional mobile terminals. BTSs serving SAIC terminals can transmit at lower power levels. This reduces the overall level

of interference in the network.

SAIC Working PrincipleGSM uses GMSK modulation, which has I and Q channels and carries the same information in both channels. The (I channel) and (Q channel) data are considered as if they are coming from two separate antennas “Space Diversity” and then use diversity combining algorithms to suppress interference.

The received signal is over sampled at 2 and treat the I and Q parts for the on-time and delayed samples as four virtual channels, space (I & Q channels), and time diversity (2 Over sampled).

It then estimates the interference in the Midamble (training sequence) part and applies the inverse of this correlation matrix to suppress the interference in the data part.

Block Diagram of SAIC Receiver

The timing estimation block corrects the burst timing with respect to burst reception. Unfold the complex signal into a real-valued vector signal with twice as many samples by

multiplexing the I and Q parts. The correlation matrix of this unfolded signal fully captures the I–Q correlation.

The basic idea of I–Q whitening is to remove I–Q correlation (ideally I and Q correlation is zero) of the received signal based on an estimate of the interference signal.

The channel is re-estimated from the whitened signal. The pre-filter down-samples to 1 oversampling and converts the channel estimate into

its minimum phase equivalent, thus moving the energy towards the first channel taps. The equalizer detects the received soft-bits.

Basic Knowledge:Diversity refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics.

Time diversity implies that the same data is transmitted multiple times, the multiple replicas of the signal will be uncorrelated if the time separation among the samples is sufficiently large.

Space diversity is relies on the fact that the data coming to the receiver are from sufficiently separated antennas and independent of each other.

Diversity combining is the technique applied to combine the multiple received signals “branches” of a diversity reception device into a single improved signal

De-correlation is a general term for any process that is used to reduce autocorrelation within a signal, or cross-correlation within a set of signals, while preserving other aspects of the signal. Since the minimum possible autocorrelation for a given signal energy is achieved by equalizing the power spectrum of the signal to be similar to that of a white noise signal, this is often referred to as “signal whitening”.

Sampling process is to modulate an input signal by a sampling signal. This reflects the original signal spectrum at multiples of the sampling frequency (). These reflections are called aliases. In the diagram below, the original spectrum is shown in green, and the first two sets of aliases are shown in a light grey-blue.

The original spectrum must be limited to less than half of the sampling rate. Ideally this would be done with a rectangular low pass filter. Without an appropriate filter, the original spectrum could extend past /2, as shown in the following diagram.

Oversampling is the process of sampling a signal with a sampling frequency significantly higher than twice the bandwidth or highest frequency of the signal being sampled. Oversampling helps avoid aliasing, improves resolution and reduces noise.An oversampled signal is said to be oversampled by a factor of β, defined as

where: is the sampling frequencyB is the bandwidth or highest frequency of the signal; the Nyquist rate is 2B.

If multiple samples are taken of the same quantity with uncorrelated noise added to each sample, then averaging N samples reduces the noise power by a factor of 1/N.

Joint Detection (JD)Multiuser detection (joint detection) is one of the receiver design technology for The simultaneous detection of the desired and the interfering signal.

In order to do this, JD methods rely on the identification of Training Sequence Code (TSC) of the interferer and its offset from the TSC of the desired signal.

On this basis, a joint channel estimation is conducted using the 26 known bits from the interfering TSC and the corresponding bits from the desired signal. The resulting refined channel estimate takes into account the effect of the interfering burst, which improves the accuracy of the estimate and thereby decreases the BER.

The two channel estimates are then used in a joint detector, which simultaneously detects the desired and the interfering signal.

The basic difference between JD and blind interference cancellation (BIC) such as SAIC is that the JD receivers attempt to jointly process (demodulate) both the desired signal and one or more of the interferers, while BIC receivers only process (demodulate) the desired signal while canceling or suppressing the interference.

Interference Rejection Combining (IRC)

Interference Rejection Combining (IRC) is an interference suppression algorithm which significantly improves the uplink radio quality. This can increase radio network capacity and improve both speech quality and data throughput.

Simulations show that IRC can provide a C/I gain of up to 11 dB, with a value in typical urban environments of around 5-6 dB, compared to the currently used receive algorithm.

A prerequisite for IRC is that two receive antennas (receive antenna diversity) are used. This means that there are two versions of the signal available in the transceiver that are slightly different due to the antenna diversity.

IRC also uses Training Sequence Code by comparing the received signal with the training sequence to estimate the characteristics of the interfering signal. The IRC algorithm can utilize this information to efficiently remove interference from the wanted signal.

IRC performs best when the desired signal and the interfering signal are synchronized in time, since then the interfering signal is the same during the whole burst and the interference characteristics estimated during the training sequence are more likely to be valid for the whole burst

Space Time Interference Rejection Combining (STIRC)In a multiple-antenna receiver, there is a strong correlation (statistical relationship) in the interference between different branches (normal and diversity) and samples for each symbol period. Usually, the interference correlation is different from the correlation of the wanted signal.

IRC is a set of diversity combining, digital signal processing methods that removes interference by taking these cross correlations into account.

These methods can be considered as whitening the interference (there is no correlation) between the individual branches and samples of each symbol which, if done perfectly, optimizes the performance of the receiver, in particular the bit detection (the process that decides the probability that a 1 or 0 was transmitted).In the IRC algorithm, the interference correlation between normal and diversity branches and between two samples per symbol in each branch are considered and treated separately. This is not an optimal approach, as not all the cross correlations between the branches and samples per symbol are considered fully.

STIRC considers all these cross correlations at the same time and, in this way, can improve the interference rejection properties of the receiver. STIRC works best when there is a single dominant interferer and it is best suited for urban areas.

Successive Interference Cancellation (SIC) ReceiverThe receiver decodes the information of both the users in two stages: In the first stage, it decodes the data of user 1, treating the signal from user 2 as Gaussian

interference. Once the receiver decodes the data of user 1, it can reconstruct user 1’s signal and

subtract it from the aggregate received signal. The receiver can then decode the data of user 2.

www.huawei.com

Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.

Security Level: Internal Use

GBSS13.0 BSC6900 (V900R013C00) VAMOS Feature Description

Huawei Implementation of Voice services over Adaptive Multi-user

Orthogonal Sub-channels (VAMOS)

VAMOS Full Rate Channel is not supported by Huawei GBSS13.0

Implementation PrinciplesVAMOS Channel Multiplexing:VAMOS multiplexing multiplexes two suitable users onto one HR channel by using channel assignment or intra-cell handover. In normal cases, when user A and user B access the network independently, each occupies

one half-rate channel. If user A and user B meet the multiplexing conditions, the BSC hands user B over to the channel occupied by user A.

If user B is accessing the network and meets the multiplexing conditions, the BSC directly assigns user B to the channel occupied by user A.

VAMOS Channel Demultiplexing: The BSC hands user B over to another half-rate channel. VAMOS channel demultiplexing can be performed based on load or quality.VAMOS Mute SAIC MS Identification: In the live network, some MSs support SAIC but the reported value of CLASSMARK3 is

Non-SAIC. These MSs are Mute SAIC MSs. At present, there is no commercial MS that supports VAMOS-1 or VAMOS-2. These non-SAIC MSs can only occupy channels with MSs that support VAMOS-2. To enhance VAMOS multiplexing, the BSC provides an effective testing mechanism to identify Mute SAIC MSs.

The BSC sets up an MS SAIC database to record whether an MS is a Mute SAIC MS. During channel multiplexing, the BSC queries the records in the MS SAIC database to identify Mute SAIC MSs and non-SAIC MSs. Then the BSC selects proper MSs to pair with these MSs.

VAMOS Problem SAIC MS Identification (VAMOS Call Drop Solution):A database is created at the BSC to record whether the MSs under the BSC have defects in SAIC. All the MSs under the BSC are classified into three types: defective SAIC-capable MSs that cannot use VAMOS, defective SAIC-capable MSs that can use VAMOS but require alpha hopping modulation, and normal SAIC-capable MSs that can use VAMOS but require alpha-QPSK modulation. Before allocating a channel to an MS, the BSC determines the MS type and the required modulation scheme by checking the records in the database.

Call drops may occur on some SAIC MSs during channel multiplexing. To ensure VAMOS capacity gains, the BSC provides a testing mechanism to identify these problem SAIC MSs.

During channel multiplexing, the BSC selects proper MSs to pair with the problem MSs and uses corresponding power control strategy to ensure the speech quality of VAMOS calls.

The BSC uses an MS SAIC database to record the SAIC flags of various MSs. The SAIC flag indicates whether an MS supports VAMOS multiplexing and the modulation method that the MS uses.

During channel multiplexing, the BSC checks the MS SAIC database to identify problem SAIC MSs that do not support multiplexing, problem SAIC MSs that support multiplexing by using hopping alpha modulation, and non-problem SAIC MSs that support multiplexing by using Alpha-QPSK modulation.

Then the BSC selects proper MSs to pair with these MSs. The BSC also uses corresponding power control strategies to ensure the speech quality of VAMOS calls

MS CompatibilityBefore enabling VAMOS on a newly deployed BSC, you are advised to enable Mute SAIC MS Identification and VAMOS Call Drop Solution. The MS identification should be enabled for one month and disabled afterwards. The period can be adjusted based on MS SAIC database and SAIC Ratio.

Based on results from SAIC MS identification, SAIC MSs are categorized into three types: White SAIC MSs: This type of MSs can completely support VAMOS multiplexing. Gray SAIC MSs: The performance of this type of MSs varies with the TSC combination. The

hop-Alpha QPSK modulation mode, however, can be used to upgrade the MS performance.

Black SAIC MSs: are problem SAIC MSs that do not support multiplexing.

If MS compatibility is not considered, the BSC implements multiplexing based on the VAMOS support capability reported by the MS by using the Classmark.

If VAMOS is enabled on one of the operator's BSCs, the MS SAIC database can be shared with other BSCs that need to enable VAMOS.

If MS compatibility is considered, the BSC obtains the MS type and then implements multiplexing based on the MS compatibility stored in the MS type database.

Multiplexing priorities for MSs:

For the last two conditions with the lowest priorities, whether multiplexing can be performed is controlled by a switch. The switch is turned off by default. You are advised not to turn on this switch.

Priority Candidate MS 1 Candidate MS 11 White SAIC MS VAMOS-1 MS2 White SAIC MS VAMOS-2 MS3 VAMOS-1 MS VAMOS-2 MS4 White SAIC MS White SAIC MS5 VAMOS-1 MS VAMOS-1 MS6 VAMOS-2 MS VAMOS-2 MS7 Gray SAIC MS VAMOS-1 MS8 Gray SAIC MS VAMOS-2 MS9 Gray SAIC MS Gray SAIC MS

10 Gray SAIC MS White SAIC MS11 Non-SAIC MS VAMOS-2 MS12 Non-SAIC MS VAMOS-1 MS13 Non-SAIC MS White SAIC MS

VAMOS Acceptance:

VAMOS Implementation Steps:

1- Choose cells with high congestion rate and no VAMOS Limitation.

2- Calculate the expected VAMOS Gain.

3- TSC Re-planning.

4- Open Detection.

5- Activation of VAMOS.

6- Calculate actual VAMOS Gain.

7- Assigned complex command (if VAMOS Gain is low and need to be improved).

8- Reported IMEI

9- Monitor VAMOS Cells KPIs.

Steps in Detail:1- VAMOS Cell Screening (VAMOS Limitation): BTS Version after BSC6900V900R013C00 VAMOS Supported Boards: MFRU, MRRU, DRFU, DRRU, DTRU. MFRU ≤ 4 TRXs Don't use Dual times slot DL/UL DTX = YES Open Power Control 3.5 FLEXMAIO = OFF DLFREQADJ = DISABLE Need DOUBLEDOUBLE_ANTENNA MEASURETYPE don't use EnhMeasReport FIX_16K_ABIS = YES (Flex Abis only) [LST BTS ---> to check fix 16K_abis] NBAMRTFOSWITCH = DISABLE (deactivate tandem free operation) TCH2SDPREEN = OFF2- Expected VAMOS Gain: How many VAMOS calls from the total traffic.3- TSC Re-planning: Avoid Co-BCCH/Co-BCC in serving area of VAMOS Cell.

4- Open Detection: Import MS data base Open SAIC PWR Control for cell SAIC MS detection for BSC SAIC MS detection for Cell5- Activation of VAMOS: VAMOS activation for Cell. VAMOS PWR Control setting for cell. More settings in case of Concentric cells. Opening Mute SAIC switch for cell (if VAMOS Gain is low)6- Calculate actual VAMOS Gain 7- Assigned Complex Command: Opening VAMOS assignment switch for cell Open SDCCH-WAIT MEASUREMENT switch for cell8- Reported IMEI: Report IMEI switch for BSC

1- VAMOS Cell Screening (VAMOS Limitation): MFRU ≤ 4 TRXs:After VAMOS is enabled, more BTS destination signaling point (DSP) processing resources are required (the number of channels to be processed concurrently increases and new modulation algorithms need to be used), and the service processing capability of the BTS deteriorates.

Don't use Dual time slot:The Cell Extension Type must be Normal_cell. Because VAMOS feature couldn’t recognize that the other TCH can’t be used.

One of the two adjacent TCHs with the same TRX number is not displayed

DL/UL DTX = YESDTX reduces the data to be transmitted during inactive speech periods, thus reducing the system interference and saving system resources. In addition, DTX reduces the workload of the TX module of the MS, thus enabling the MS to enjoy a longer call duration and standby time.

VAMOS Operation in Discontinuous Transmission

If DTX is activated in the downlink and one of the sub-channels enters DTX mode (due to e.g. a silent period), only the active sub-channel is transmitted.

This allows the use of GMSK modulation with linearized GMSK pulse shape as for legacy channels.

This has the advantage that the power of the GMSK transmission compared to AQPSK can be reduced during this period by for example 3 dB, since the signal energy for the remaining active user doubles compared to ordinary QPSK transmission when both users are active.

Once the sub-channel in DTX mode needs to transmit a silence indicator description (SID FIRST, SID-UPDATE, ONSET, NODATA) or re-enters the next speech activity period, the AQPSK modulation scheme is selected.

Open Power Control 3.5The MRs of two VAMOS multiplexed users are preprocessed separately. In downlink alpha-QPSK power control, or uplink SIC power control the optimized Huawei power control algorithm III must be enabled. Since, MR preprocessing procedures, such as interpolating and filtering, are the same as that in the optimized Huawei power control algorithm III

FLEXMAIO = OFFIn a site with large capacity, inter-frequency or intra-frequency interference may easily occur among channels because of the limited frequency resources and the aggressive frequency reuse. For example, when the MA has some neighbor frequencies, inter-frequency interference may occur among the channels if the channels that carry the same number of the timeslot on different TRXs use neighbor MAIOs and the channels are seized. If the Flex MAIO function is performed so that an MAIO is assigned to a certain channel under activation, the MAIO value is dynamically adjusted based on the interference on the current channel. The MAIO value is assigned to the channel so that the interference for the call is minimized from the perspective of the entire network. The Huawei BSS equipment records the interference conditions in each timeslot and updates the timeslot interference record upon channel activation or channel release.

DLFREQADJ = DISABLEDeactivate Automatic Frequency Correction (AFC) feature:AFC is a frequency correction algorithm used on the base station side for fast-moving MSs. It ensures reliability of radio links carrying high-quality speech services for MSs moving at 500 km/h and also ensures service continuity.

The “DL Frequency Adjust Switch” parameter must set to “NO”The parameter determines whether to enable the automatic frequency adjustment function in the downlink for the BTS. When the parameter is set to YES, the BTS starts the automatic frequency adjustment algorithm in the downlink to compensate the fast-moving MS for the frequency offset caused by the Doppler Effect. While enabling the automatic frequency adjustment in the downlink, enable the automatic frequency adjustment in the uplink simultaneously.

DOUBLEDOUBLE_ANTENNALST BTSRXUBP: to check Need DOUBLESINGLE_ANTENNA Sending and Receiving mode of the BTS3900E boardSGL_ANTENNA(Single Feeder[1TX + 1RX]), DOUBLESINGLE_ANTENNA(Double Feeder[1TX + 1RX]), DOUBLEDOUBLE_ANTENNA(Double Feeder[1TX + 2RX])VAMOS feature required 2RX as per IRC algorithm. MEASURETYPE don't use EnhMeasReportMeasurement Report Type:ComMeasReport (Common Measurement Report) EnhMeasReport (Enhanced Measurement Report)The Enhanced Measurement Report supports the measurement of 3G neighboring cells to implement the interoperability between the 2G system and 3G system, and thus ensures the service continuity.The Enhanced Measurement Report also provides the system with information such as Downlink Frame Erasure Rate (DL FER), the usage of Bit Error Probability (BEP)instead of RX Quality during the DTX frames.

NBAMRTFOSWITCH = DISABLE A mobile to mobile GSM call will always have two PCM links in the connection, one to and from each transcoder and thus a GSM call is always established using the G.711 codec. The two transcoders of the connection are also called a tandem.

If both transcoder units support at least a single common codec like AMR 12.2 or an AMR-WB codec, the 64 kbit/s G.711 connection is used to tunnel the compressed and encoded voice stream. As the audio stream is compressed most of the bits of the transparent 64 kbit/s stream are not used. This effectively removes the transcoder tandem from the voice connection and is thus called Tandem Free Operation.

TFO solves the problem of speech signal damage in repeated encoding and decoding by canceling one encoding and decoding process to improve the signal quality.

TFO prerequisite: The speech versions of the calling and called parties in the FR/EFR/HR services must be the same, otherwise the establishment of TFO links will be abort and restore normal operation.

TFO must be disabled, because it’s conflicts with VAMOS feature.

TCH2SDPREEN = OFFTCH Pre-Conversion into SDCCH SwitchSwitch of TCH pre-conversion into SDCCH. When this switch is turned on, the BSC pre-converts some TCHs into SDCCHs. During peak traffic hours, the BSC converts the SDCCHs back into TCHs.

2- Expected VAMOS Gain:The capacity gain provided by VAMOS is dependent on several factors, for example the number and type of terminals supporting VAMOS, frequency load in the network, cell size and cell plan.

VAMOS Gain (%) = VAMOS Area (%) SAIC Ratio (%) AHS Ratio (%)

VAMOS Area: the no. of MRs that achieve the quality threshold of VAMOS.[Number of MRs on Downlink TCHH (Receive Level Rank 4 to 7 and Receive Quality Rank 0 and 1) + Number of MRs on Downlink TCHF (Receive Level Rank 4 to 7 and Receive Quality Rank 0 and 1)] / Number of MRs on Downlink TCHF and TCHH (Receive Level Rank 0 to 7 and Receive Quality Rank 0 and 7)

SAIC Ratio: the Calls penetration that originated or terminated using SAIC Supported MSs. A03628:Number of Calls Originated or Terminated by MSs Supporting SAIC/A03640:Number of Calls

AHS (Adaptive Half-rate Speech): the half-rate penetration of the cellK3034:TCHH Traffic Volume/K3014:Traffic Volume on TCH

3- TSC Re-planning:After VAMOS is enabled, two MSs use the same TCHH and different Training SequenceCodes (TSCs). Currently, no VAMOS I or VAMOS II MS that support new TSCs is available,and only TSCs 0 to 7 can be used.

If all cells are enabled with VAMOS, two TSCs are needed for each cell. As a result, TSCs are more tightly reused and the cells that use the same TSC become closer. To avoid the situation that the MSs in different cells use the same frequency and the same TSC, you need to re-plan TSCs to expand the distance between cells that use thesame TSC.

So that the cells must avoid any Co-BCC Co-BCCH for the two orthogonal TSCs (BCCs):

BCC Planning (avoid Co-BCC of these pairs):

0-2 & 2-0 1-7 & 7-1 3-4 & 4-3 5-6 & 6-5

(Note: if we use 1-7,we have to set {SaicAlphaJumpValue=4})Faulty SAIC MS Alpha Hop Modulate Value: Alpha value used for Alpha hopping modulation during VAMOS multiplexing on a SAIC-capable MS with AFC defects or during the identification of such MSs.

4- Open detection: Import MS data base: Run ADD GMSSAICCAP to set the MS type database on the BSC, that is, add MSs in the white list and gray list manually.

Notes: You can configure up to 20,000 records in the white list and gray list in

total. If ADD it means New TAC and if MOD it was a blacklist in other network or

other country and it is not in our network Importing MS data base will be done for each BSC containing VAMOS Cell.

Open SAIC PWR Control for cell: If the MS support SAIC, thesystem can decrease the DL expected receive quality level automatically.

SAICALLOWED = YES Power Control Threshold Adjust for SAIC = 3

SAIC MS detection for BSC Required Auto Mute SAIC Identify Times = 100Number of times automatic mute SAIC-capable MS identification is performed for a specified Alpha value.Required Times for Identifying Mute SAIC = 70 Number of times required for identifying an MS as a mute SAIC-capable MS. When the number of times an MS is detected as a mute SAIC-capable MS is greater than or equal to the value of this parameter for a specified Alpha value after the identification is performed for "Required Auto Mute SAIC Identify Times", the MS is identified as a mute SAIC-capable MS.Times for Identify Problem SAIC Terminal = 200Number of times identification of SAIC-capable MS with AFC defects is performedProblem SAIC Terminal Identify Threshold = 60Number of times required for identifying an MS as a SAIC-capable MS with AFC defects. When the number of times an MS is detected as a SAIC-capable MS with AFC defects is greater than or equal to the value of this parameter for a specified Alpha value after the identification is performed for "Times for Identify Problem SAIC Terminal", the MS is identified as a SAIC-capable MS with AFC defects.Upper Alpha Thres for Mute SAIC Identify = 16 Upper threshold of the Alpha value in the mute SAIC-capable MS identification. To ensure voice quality and reliability of the testing, several rounds of testing need to be performed with values between "Upper Alpha Thres for Mute SAIC Identify" and "Lower Alpha Thres for Mute SAIC Identify".Lower Alpha Thres for Mute SAIC Identify = 10Lower threshold of the Alpha value in the mute SAIC-capable MS identification. To ensure voice quality and reliability of the testing, several rounds of testing need to be performed with values between "Upper Alpha Thres for Mute SAIC Identify" and "Lower Alpha Thres for Mute SAIC Identify".

SAIC MS detection for CellVAMOS Switch = ONPrimary TSC in VAMOS = 4 & Secondary TSC in VAMOS = 3Before all calls enter the VAMOS mode, the primary TSC is assigned preferentially; after a pair of VAMOS calls are multiplexed, the TSC that is not used by the call that accesses the timeslot first is assigned to the other call.Mute SAIC Terminal Processing Switch = ONWhether to enable the function for processing mute SAIC-capable MSs in a cell. A mute SAIC-capable MS is a SAIC-capable MS that is reported as SAIC-incapable. Processing mute SAIC-capable MSs consists of identification of such MSs based on database records and automatic identification of such MSs.Auto Mute SAIC Identification Switch = ONWhether to enable automatic identification of mute SAIC-capable MSs in a cell. A mute SAIC-capable MS is a SAIC-capable MS that is reported as SAIC-incapable. When this parameter is set to ON, the downlink DTX must be disabled, which has impact on network interference. The Alpha-QPSK modulation scheme is used in the downlink, deteriorating downlink receive quality.Problem SAIC Terminal Processing Switch = ONWhether to enable the function for processing SAIC-capable MSs with AFC defects in a cell. Processing SAIC-capable MSs with AFC defects consists of identification of such MSs based on database records and automatic identification of such MSs.

Problem SAIC Terminal Identify Switch = ONWhether to enable automatic identification of SAIC-capable MSs with AFC defects in a cell. Max Calls in Terminal Identification = 15Maximum number of calls in a cell, on which identification of mute SAIC-capable MSs and identification of SAIC-capable MSs with AFC defects can be performed simultaneously.LO Thresh upon Terminal Identify Request = 40Load threshold for performing automatic identification of mute SAIC-capable MSs and SAIC-capable MSs with AFC defects in a cell. MS identification request is triggered only when cell load is lower than or equal to the value of this parameter.UL RX Qual Thres of Terminal Identify= 10Threshold of the uplink receive quality of a call for triggering automatic identification of mute SAIC-capable MSs and SAIC-capable MSs with AFC defects. When the uplink receive quality of a call is lower than or equal to the value of this parameter, automatic identification of such MSs is performed.DL RX Qual Thres of Terminal Identify = 10Threshold of the downlink receive quality of a call for triggering automatic MS identification. When the downlink receive quality of a call is lower than or equal to the value of this parameter, automatic identification of mute SAIC-capable MSs and SAIC-capable MSs with AFC defects is performed.

ATCB Thres of Terminal Identify = 68ATCB threshold of a call for triggering automatic MS identification. When the ATCB of a call is greater than or equal to the value of this parameter, automatic identification of mute SAIC-capable MSs and SAIC-capable MSs with AFC defects is performed.Watch Time for Terminal Identify = 3Observation period for uplink and downlink quality and ATCB of a call.Satisfy Time for Terminal Identify = 3 Time during which uplink and downlink quality and ATCB of a call meet the thresholds for triggering identification of mute SAIC-capable MSs and SAIC-capable MSs with AFC defects. If the time during which uplink and downlink quality and ATCB of a call meet the thresholds within "Watch Time for Terminal Identify" is greater than or equal to the value of this parameter, the identification is triggered.Periods for Auto Mute SAIC Identify = 1Number of periods for mute SAIC-capable MS identification, which is used to calculate the total time for mute SAIC-capable MS identification. Total time = "Periods for Auto Mute SAIC Identify" x 2 x "MRs in a Auto Mute SAIC Identify Period" x MR period (480 ms)MRs in a Auto Mute SAIC Identify Period = 10Number of measurement reports in one period for mute SAIC-capable MS identification. Period for mute SAIC-capable MS identification = "MRs in a Auto Mute SAIC Identify Period" x MR period (480 ms)

Average RX Qual Difference Threshold = 32Threshold of average receive quality difference. If average downlink receive quality difference between the former and the current modulating scheme is greater than or equal to the value of this parameter, average receive quality is considered as abnormal.Abnormal Average RX Qual Times Threshold = 1Threshold of the number of times the average receive quality is abnormal. If the number of times is greater than or equal to the value of this parameter, SAIC-capable MS identification is terminated and the MS is considered as SAIC-incapable.Auto Identify Periods for Faulty SAIC MS = 1Number of periods for identification of SAIC-capable MSs with AFC defects, which is used to calculate the total time for identification of SAIC-capable MSs with AFC defects. Total time = "Auto Identify Periods for Faulty SAIC MS" x 2 x "Faulty SAIC MS Auto Identify Period" x MR period (480 ms)Faulty SAIC MS Auto Identify Period = 10Number of measurement reports in one period for identification of SAIC-capable MSs with AFC defects. Period for identification of SAIC-capable MSs with AFC defects = "Faulty SAIC MS Auto Identify Period" x MR period (480 ms).Faulty SAIC MS Mean RX Qual Differ Thres = 32Threshold of average receive quality difference for abnormal RX quality of a SAIC-capable MS with AFC defects. If average downlink receive quality difference between Alpha hopping modulation and GMSK modulation is greater than or equal to the value of this parameter, average downlink receive quality is considered as abnormal. If average uplink receive quality difference between the former and the current GMSK modulation within two "Faulty SAIC MS Auto Identify Period" is greater than or equal to the value of this parameter, average uplink receive quality is considered as abnormal.

Faulty SAIC MS Mean RX Qual Abnor Thres = 1Threshold of the number of times the average receive quality is abnormal. If the number of times is greater than or equal to the value of this parameter, identification of SAIC-capable MSs with AFC defects is terminated and the MS is considered as a SAIC-capable MS with AFC defects. VAMOS multiplexing will be prohibited for the MS.Faulty SAIC MS Alpha Hop Modulate Period = 2Period of Alpha hopping modulation during VAMOS multiplexing on a SAIC-capable MS with AFC defects or during the identification of such MSs.Faulty SAIC MS Alpha Hop Modulate Value = 2Alpha value used for Alpha hopping modulation during VAMOS multiplexing on a SAIC-capable MS with AFC defects or during the identification of such MSs.

5- Activation of VAMOS: VAMOS activation for Cell:VAMOS Switch = ONAllow Channel Multiplex in Assignment = OFFWhen VAMOS Switch and Allow Channel Multiplex in Assignment are set to ON, the network congestion rate decreases significantly; however, network quality decreases after VAMOS calls are multiplexed.Channel Multiplex Load Thres = 0Load threshold for triggering VAMOS channel multiplexing in a cell. When the load of a cell is higher than or equal to this threshold, the decision on channel multiplexing is triggered.Allow Channel Multiplex via In-Cell HO = ON Whether to enable VAMOS channel multiplexing through intra-cell handover in the network.ATCB Thres. of Established Non-SAIC Calls = 82ATCB threshold of an established non-SAIC call to be selected as a candidate call for VAMOS channel multiplexing. The decision on an established Non-SAIC call can be triggered successfully only when the following conditions are met: The ATCB of the call is greater than or equal to the value of this parameter. The uplink receive quality is lower than or equal to "UL Rx Qual. Thres. of Established Calls". The downlink receive quality is lower than or equal to "DL Rx Qual. Thres. of Established Calls". If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.ATCB Thres. of Established SAIC Calls = 66 ATCB threshold of an established SAIC call to be selected as a candidate call for VAMOS channel multiplexing. The decision on an established SAIC call can be triggered successfully only when the following conditions are met: The ATCB of the call is greater than or equal to the value of this parameter. The uplink receive quality is lower than or equal to "UL Rx Qual. Thres. of Established Calls". The downlink receive quality is lower than or equal to "DL Rx Qual. Thres. of Established Calls". If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.

ATCB Thres. of Established VAMOS-1 Calls = 76ATCB threshold of an established VAMOS-1 call to be selected as a candidate call for VAMOS channel multiplexing. The decision on an established VAMOS-1 call can be triggered successfully only when the following conditions are met: The ATCB of the call is greater than or equal to the value of this parameter. The uplink receive quality is lower than or equal to "UL Rx Qual. Thres. of Established Calls". The downlink receive quality is lower than or equal to "DL Rx Qual. Thres. of Established Calls". If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.ATCB Thres. of Established VAMOS-2 Calls = 74ATCB threshold of an established VAMOS-2 call to be selected as a candidate call for VAMOS channel multiplexing. The decision on an established VAMOS-2 call can be triggered successfully only when the following conditions are met: The ATCB of the call is greater than or equal to the value of this parameter. The uplink receive quality is lower than or equal to "UL Rx Qual. Thres. of Established Calls". The downlink receive quality is lower than or equal to "DL Rx Qual. Thres. of Established Calls". If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.UL Rx Qual. Thres. of Established Calls = 10Threshold of the uplink receive quality of an established call to be selected as a VAMOS candidate call. The decision on this call can be triggered successfully only when the following conditions are met: The ATCB of this call is greater than or equal to the ATCB threshold. The uplink receive quality is lower than or equal to the value of this parameter. The downlink receive quality is lower than or equal to "DL Rx Qual. Thres. of Established Calls". If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.

DL Rx Qual. Thres. of Established Calls = 10Threshold of the downlink receive quality of an established call to be selected as a VAMOS candidate call. The decision on this call can be triggered successfully only when the following conditions are met: The ATCB of this call is greater than or equal to the ATCB threshold. The downlink receive quality is lower than or equal to the value of this parameter. The uplink receive quality is lower than or equal to "UL Rx Qual. Thres. of Established Calls". If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.Watch Time of Candidate Calls = 3Duration within which the ATCB and receive quality of a call are observed to determine whether this call can be selected as a VAMOS candidate call. If the decision is triggered for "Duration of Satisfying Candidate VAMOS Call" within the period of time specified by this parameter, this call can be selected as a VAMOS candidate call.Duration of Satisfying Candidate VAMOS Call = 2Duration within which a call satisfies the decision conditions for selecting a VAMOS candidate call. If the decision conditions are met for "Duration of Satisfying Candidate VAMOS Call" within "Watch Time of Candidate Calls", this call can be selected as a VAMOS candidate call.Allow VAMOS-1&NonSAIC and SAIC&NonSAIC = OFF Whether to allow the multiplexing of a VAMOS-1 call and a non-SAIC call and the multiplexing of a SAIC call and a non-SAIC call. The value ON indicates that the two types of multiplexing are allowed; the value OFF indicates that the two types of multiplexing are not allowed.

Path Loss Offset Thres. of VAMOS Call = 20 Threshold of the absolute value of the path loss difference between two calls for VAMOS channel multiplexing. When the absolute value of the path loss difference between two calls is smaller than or equal to this threshold, the two calls are allowed to be multiplexed.Channel Demultiplex on Low Cell Load = OFFWhether to enable VAMOS channel demultiplexing when the load in a cell is low. The value ON indicates that VAMOS channel demultiplexing due to low cell load is enabled; the value OFF indicates that VAMOS channel demultiplexing due to low cell load is disabled.Channel Demultiplex on Bad Qual. = ONWhether to enable VAMOS channel demultiplexing when the speech quality of a call is poor. When "VAMOS Switch" is set to ON, this parameter must be set to OFF if Huawei I handover algorithm is enabled in the existing network and ON if Huawei II handover algorithm is enabled in the existing network.DL RX Bad Qual. Demultiplex Thres. = 55Downlink receive quality threshold of a VAMOS call in channel demultiplexing due to poor speech quality in a cell. When the downlink receive quality is higher than or equal to this threshold or the uplink receive quality is higher than or equal to "UL RX Poor Qual. Demultiplex Thres.", the decision of channel demultiplexing due to poor speech quality is triggered. If the decision conditions are met for "Poor Qual. Duration for Demultiplex" within "Watch Time of Poor Qual. for Demultiplex", a call can be demultiplexed through handover.

UL RX Bad Qual. Demultiplex Thres. = 55Uplink receive quality threshold of a VAMOS call in channel demultiplexing due to poor speech quality in a cell. When the uplink receive quality is higher than or equal to this threshold or the downlink receive quality is higher than or equal to "DL RX Poor Qual. Demultiplex Thres.", the decision of channel demultiplexing due to poor speech quality is triggered. If the decision conditions are met for "Poor Qual. Duration for Demultiplex" within "Watch Time of Poor Qual. for Demultiplex", a call can be demultiplexed through handover.Watch Time of Bad Qual. for Demultiplex = 1 Duration for observing the receive quality of a VAMOS call in the decision of channel demultiplexing due to poor speech quality in a cell.Bad Qual. Duration for Demultiplex = 1Duration in which a call satisfies the conditions for channel demultiplexing due to poor speech quality in a cell. Within "Watch Time of Poor Qual. for Demultiplex", a call can be demultiplexed only when it satisfies the conditions for "Poor Qual. Duration for Demultiplex".Mute SAIC Terminal Processing Switch = ONWhether to enable the function for processing mute SAIC-capable MSs in a cell. A mute SAIC-capable MS is a SAIC-capable MS that is reported as SAIC-incapable. The value ON indicates that the function for processing such MSs is enabled; the value OFF indicates that the function for processing such MSs is disabled. Processing mute SAIC-capable MSs consists of identification of such MSs based on database records and automatic identification of such MSs.Problem SAIC Terminal Processing Switch = ONWhether to enable the function for processing SAIC-capable MSs with AFC defects in a cell. The value ON indicates that the function for processing such MSs is enabled; the value OFF indicates that the function for processing such MSs is disabled. Processing SAIC-capable MSs with AFC defects consists of identification of such MSs based on database records and automatic identification of such MSs.

VAMOS PWR Control setting for cell:

After VAMOS is enabled, power control is performed to mitigate the interference of multiplexed users to each other and to the entire network. Otherwise, the speech quality of the multiplexed users and the

entire network decreases. Power control performed in VAMOS consists of Uplink SIC power control and Downlink alpha-QPSK power control.

Allow alpha-QPSK Power Control = ON Whether to enable the alpha-QPSK power control algorithm in VAMOS.Rx Qual. Thres. in alpha-QPSK PC of HR = 2When the downlink receive quality of a VAMOS HR call is lower than this threshold, the BTS power is reduced. When the downlink receive quality of a VAMOS HR call is higher than this threshold, the BTS power is boosted. When the downlink receive quality of a VAMOS HR call is equal to this threshold, the BTS power remains unchanged. If this parameter is set to a large value, the downlink power required by an HR call increases, the interference in the network increases, and the network quality deteriorates.Rx Qual. Thres. in alpha-QPSK PC of AMR HR = 2RX Level Thres. in alpha-QPSK PC = 20When the downlink receive level of a VAMOS call is higher than this threshold, the BTS power is reduced; when the downlink receive level of a VAMOS call is lower than this threshold, the BTS power is boosted; when the downlink receive level of a VAMOS call is equal to this threshold, the BTS power remains unchanged.RX Level Protect Factor in alpha-QPSK PC = 20Protection factor of the downlink receive level used in the alpha-QPSK power control algorithm. The parameter setting affects the speed of adjusting the BTS power.

RX Qual. Protect Factor in alpha-QPSK PC = 60Protection factor of the downlink receive quality used in the alpha-QPSK power control algorithm. RX Level Adjust Factor in alpha-QPSK PC = 30Adjustment factor of the downlink receive level used in the alpha-QPSK power control algorithm. The parameter setting affects the speed of adjusting the BTS power.RX Qual. Adjust Factor in alpha-QPSK PC = 40Adjustment factor of the downlink receive quality used in the alpha-QPSK power control algorithm. Alpha Adjust Range in alpha-QPSK PC = 2 Range of alpha adjustment in the alpha-QPSK downlink power control algorithm. If this parameter is set to 4, alpha can be adjusted in the range of -4 to 4. If this parameter is set to 0, the Orthogonal Sub Channel (OSC) mode is used.Allow SIC Power Control = ONWhether to enable uplink Successive Interference Cancellation (SIC) power control algorithm in VAMOS.Rx Qual. Thres. in SIC PC of HR = 15Uplink receive quality threshold of HR channels that are enabled with the SIC power control algorithm. When the uplink receive quality of a VAMOS HR call is lower than this threshold, the MS power is reduced. When the uplink receive quality of a VAMOS HR call is higher than this threshold, the MS power is boosted. When the uplink receive quality of a VAMOS HR call is equal to this threshold, the MS power remains unchanged.Rx Qual. Thres. in SIC PC of AMR HR = 15

RX Level Thres. in SIC PC = 20Uplink receive level threshold used in the SIC power control algorithm. When the uplink receive level of a VAMOS call is higher than this threshold, the MS power is reduced; when the uplink receive level of a VAMOS call is lower than this threshold, the MS power is boosted; when the uplink receive level of a VAMOS call is equal to this threshold, the MS power remains unchanged.RX Level Protect Factor in SIC PC = 30Protection factor of the uplink receive level used in the SIC power control algorithm.RX Qual. Protect. Factor in SIC PC = 75Protection factor of the uplink receive quality used in the SIC power control algorithm. RX Level Adjust Factor in SIC PC = 30Adjustment factor of the uplink receive level used in the SIC power control algorithm.RX Qual. Adjust Factor in SIC PC = 40 Adjustment factor of the uplink receive quality used in the SIC power control algorithm.SIC Offset Up Thres. in SIC PC = 15Upper threshold of the SIC offset in the SIC power control algorithm. The parameter setting affects the speed of adjusting the MS power. A higher value of this parameter prevents the use of the weak power; however, the difference between weak power and strong power is significant, the speech quality of the MS with weak power cannot be guaranteed. A lower value of this parameter increases the weak power frequently. This increases the interference between weak-power MSs and the interference to other calls, thus deteriorating network quality.

More settings in case of Concentric cells.Cell Optimized Reserved Parameter 11 = 32768Reserved Parameter 11 (Bits 0-7): Threshold of the downlink receive level of an established call to be selected as a VAMOS candidate call. The decision on an established call can be triggered successfully only when the following conditions are met: The downlink receive level of an established call is to this threshold. The uplink and downlink receive quality as well as the Adaptive to Cell Boarder

(ATCB) meet relevant requirements. If the decision conditions are met for Duration of Satisfying Candidate VAMOS Call within Watch Time of Candidate Calls, this call can be selected as a VAMOS candidate call.

Reserved Parameter 11 (Bits 8-15): Offset of the downlink receive level of a new call from the level threshold of established calls if the new call is to be selected as a VAMOS candidate call during assignment. A new call can be selected as a VAMOS candidate call only when the following conditions are met: The downlink receive level of the new call is greater than or equal to the sum of

DL Rx Lev. Thres. of VAMOS Calls and this parameter. The uplink and downlink receive quality as well as the ATCB meet relevant

requirements.

Cell Optimized Reserved Parameter 12 = 133Reserved Parameter 12 (Bits 0-7): Offset of the ATCB of a new call in the overlaid subcell from the ATCB threshold of a new call in the underlaid subcell if the new call in the overlaid subcell is to be selected as a VAMOS candidate call during allocation.

Reserved Parameter 12 (Bits 8-15): Load threshold for channel multiplexing in an overlaid subcell.

Opening Mute SAIC switch for cell (if VAMOS Gain is low):VamosSwitch=ON, SaicProMsSwitch=ON, UnkownSaicMultSwitch=ON;

6- Calculate actual VAMOS Gain

VAMOS capacity gain =

VAMOS traffic = 2 x R3501:Mean Number of Busy Channels (VAMOS TCHH)

This counter provides the number of VAMOS TCHHs in a cell. If the value of this counter is low, you can adjust the cell load threshold in VAMOS channel multiplexing, relax the decision conditions of selecting a VAMOS candidate call, or lower the thresholds such as path loss offset threshold in the decision of VAMOS channel multiplexing.

Total traffic = K3014:Traffic Volume on TCH

7- Assigned Complex Command: Opening VAMOS assignment switch for cellVamosSwitch=ON, VamosAssSwitch=ON;

Open SDCCH-WAIT MEASUREMENT switch for cellSDCCHWaitMREn=ON;

8- Reported IMEI (Mute-SAIC MS identification): Report IMEI switch for BSC:The BSC records the MS type (TAC in the IMEI) based on the BTS test result and periodically exports the records to the OMU.

SET IDRQTEST:IDRQSWITCH=ON,IDRQDURATION=65535,UserIDTraceMode=SNDONEIDRQ,UserIDTraceType=IMEI;

IMEI : International Mobile Equipment IdentificationIMEI = TAC + FAC + SNR + spare (15 digits)TAC = Type Approval Code, uniquely identify wireless devices(6 digits)FAC = Final Assembly Code, identified the manufacturer (2 digit )SNR = Serial Number( 6 digits)spare = A spare bit for future use. ( 1 digit)

You can run EXP MSSAICCAPMML to convert the BSC detection result into a man-machine language (MML) script and save it in \bam\version_x\ftp \ms_saic_cap on the OMU. Here, x refers to the specific version number.You can use the file manager on the Web LMT to export the generated MML script to a local path. Then, run the MML script to import the automatic detection result into the MS database.

VAMOS Cells KPIs – Vodafone Egypt

VAMOS Cells KPIs – Vodafone Egypt

VAMOS Cells KPIs – Vodafone Egypt

VAMOS Cells KPIs – Vodafone Egypt

References and Additional Resources: GSM/EDGE: Evolution and Performance, Mikko Saily, Guillaume

Sébire, and Dr. Eddie Riddington Mobile Handset Design, Sajal K. Das 3GPP TS 45.001: Functional description of VAMOS 3GPP TS 45.002: Channel configuration for VAMOS 3GPP TS 45.004: TX pulse shape for VAMOS 3GPP TS 45.005: VAMOS Radio performance requirements ETSI TR 145 903: Single Antenna Interference Cancellation (SAIC) Ericsson: GSM BSS Optional Features Huawei: VAMOS Deployment Guide Nokia Siemens Networks: Space Time Interference Rejection

Combining System Feature Rohde & Schwarz: VAMOS Technology Introduction