59754961-23-EDGE-Function.pdf

M900/M1800 Base Station Subsystem Feature Description Contents

Issue 02 (2007-06-30) Huawei Technologies Proprietary i

Contents

23 EDGE Function.......................................................................................................................23-1

23.1 Introduction...............................................................................................................................................23-2

23.1.1 Application.......................................................................................................................................23-2

23.1.2 Availability .......................................................................................................................................23-2

23.1.3 Restrictions ......................................................................................................................................23-2

23.2 Technical Description................................................................................................................................23-3

23.2.1 Function Overview...........................................................................................................................23-3

23.2.2 8PSK Modulation.............................................................................................................................23-3

23.2.3 Transmit Power of EDGE ................................................................................................................23-4

23.2.4 MCS-1 to MCS-9 Coding Schemes .................................................................................................23-5

23.2.5 Link Quality Control........................................................................................................................23-6

23.2.6 Dynamic Additional Sub-TS............................................................................................................23-7

23.2.7 EDGE Handover Algorithm.............................................................................................................23-7

23.3 Function Configuration .............................................................................................................................23-8

23.3.1 Configuration Process ......................................................................................................................23-8

23.3.2 Parameter .........................................................................................................................................23-9

23.3.3 Typical Cases ...................................................................................................................................23-9

23.4 Maintenance Information ........................................................................................................................23-16

23.4.1 Related Alarm ................................................................................................................................23-16

23.4.2 Related Traffic Statistic..................................................................................................................23-16

Figures M900/M1800 Base Station Subsystem

Feature Description

ii Huawei Technologies Proprietary Issue 02 (2007-06-30)

Figures

Figure 23-1 I/Q diagram of EDGE modulation................................................................................................23-4

Figure 23-2 Rate comparison between GPRS single channel and EDGE single channel ................................23-6

Figure 23-3 Configure the type of EDGE TRX..............................................................................................23-10

Figure 23-4 Configure the type of EDGE TRX..............................................................................................23-11

Figure 23-5 Set BIE Property .........................................................................................................................23-12

Figure 23-6 Port Idle Timeslot Assignment....................................................................................................23-13

Figure 23-7 Configure the type of EDGE Cell...............................................................................................23-14

Figure 23-8 TRX Property[No.5 TRX] ..........................................................................................................23-15

Figure 23-9 Cell Handover Data ....................................................................................................................23-16

M900/M1800 Base Station Subsystem Feature Description Tables

Issue 02 (2007-06-30) Huawei Technologies Proprietary iii

Tables

Table 23-1 Software versions to support EDGE...............................................................................................23-2

Table 23-2 Mapping between 8PSK symbol parameter I and modulating bit ..................................................23-4

Table 23-3 EDGE coding schemes ...................................................................................................................23-5

Table 23-4 Configure the EDGE function ........................................................................................................23-8

Table 23-5 Parameters related to EDGE function.............................................................................................23-9

Table 23-6 Performance indexes related to EDGE function...........................................................................23-16

M900/M1800 Base Station Subsystem Feature Description 23 EDGE Function

Issue 02 (2007-06-30) Huawei Technologies Proprietary 23-1

23 EDGE Function

About This Chapter

The following table lists the contents of this chapter.

Section Describes

23.1 Introduction Introduces the EDGE.

23.2 Technical Description Describes the technology of the EDGE.

23.3 Function Configuration Describes the configuration about the EDGE.

23.4 Maintenance Information Describes the maintenance information about the EDGE.

23 EDGE Function M900/M1800 Base Station Subsystem

Feature Description

23-2 Huawei Technologies Proprietary Issue 02 (2007-06-30)

23.1 Introduction

23.1.1 Application

The Enhanced Data Rate for GSM Evolution (EDGE) greatly improves the data rate of the GSM. It increases the radio interface rate about three times by adopting new modulation method and coding scheme.

EDGE includes two parts: Enhanced GPRS (EGPRS) and Enhanced Circuit Switched Data (ECSD).

EGPRS adds the 8PSK modulation. It improves the rate of single channel to about 59.2 kbit/s maximally.

ECSD is enhanced from High Speed Circuit Switched Data (HSCSD). Huawei BSS system only implements the EGPRS function. Therefore, unless otherwise stated, the EDGE mentioned in the text refers to EGPRS.

With EDGE function, you can provide high speed data service for users.

23.1.2 Availability

EDGE function needs the support of the ETR board of BTS. ETR includes RETR and DETR. RETR supports GSM900, including EGSM and RGSM. DETR supports GSM1800.

The software of BSC, BTS and PCU needs to be upgraded, as shown in Table 23-1.

Table 23-1 Software versions to support EDGE

Object Version to Support This Function

BSC G3BSC32.10101.07.1120A, G3BSC32V300R002C09 or later

PCU G3PCU35.10000.00.04.0410A or later

BTS G3BTS33.30000.00.0601A or later

23.1.3 Restrictions

The restrictions are as follows:

If the EDGE service is opened, the number of TRXs that one E1 supports is reduced under each networking mode. Thus, the number of TRXs that one BM supports is reduced.



The number of idle timeslots and TRXs configured to an E1 must meet the following conditions:

The actual number of TRXs + [the number of idle timeslots configured/8] ≤ the maximum number of TRXs allowed.

For example, under 4E1*6TRX networking mode, the maximum number of TRXs of one E1 is six, if the E1 is configured with four idle timeslots, then the E1 can be configured with five TRXs at most.

If the EDGE function is opened, the capacity of PCU RPPU is reduced. The number of PDCH that a RPPU board can activated is reduced from 120 to 100.

23.2 Technical Description

23.2.1 Function Overview

EDGE function includes:

8PSK modulation

MCS-1 to MCS-9 coding schemes

Link quality control

Dynamic Additional Sub-TS

EDGE handover algorithm

23.2.2 8PSK Modulation

GSM uses the Gaussian minimum shift keying (GMSK) modulation. GMSK represents the bit 0 or bit 1 by shifting the phase of signal. Each shifting of phase corresponds to a symbol.

EDGE uses the 8-phase shift keying (8PSK) modulation. EDGE represents the symbols through the absolute phase of signal. There are eight symbols. Each symbol is mapped into three bits, as shown in Figure 23-1. Thus, EDGE can theoretically reach to three times GSM rate.


Feature Description


Figure 23-1 I/Q diagram of EDGE modulation

Table 23-2 Mapping between 8PSK symbol parameter I and modulating bit

Modulating bits d3i,, d3i+1, d3i+2 Symbol parameter l

(1,1,1) 0

(0,1,1) 1

(0,1,0) 2

(0,0,0) 3

(0,0,1) 4

(1,0,1) 5

(1,0,0) 6

(1,1,0) 7

The performance of 8PSK is better than that of GMSK. However, the modulation threshold of 8PSK is higher than that of GMSK.

EDGE uses both 8PSK and GMSK. Different radio environments use different modulation methods. PCU automatically adjusts the modulation method according to the BEP report sent from MS.

23.2.3 Transmit Power of EDGE

From the view point of network operation, the EDGE transceiver must have the same spectrum feature as the common transceiver.



When the EDGE transceiver transmits the signal with the 8PSK modulation, its average transmit power shall be 2dB–5dB lower than that with the GMSK to meet the spectrum requirement.

When the BCCH uses the 8PSK, the transmit power can be 4dB lower than that when using GMSK at most.

23.2.4 MCS-1 to MCS-9 Coding Schemes

EDGE uses the MCS-1 to MCS-9 coding schemes, as shown in Table 23-3.

Table 23-3 EDGE coding schemes

Coding scheme Modulation Number of valid payload bits

Rate (kbit/s)

MCS-9 2 x 592 59.2

MCS-8 2 x 544 54.4

MCS-7 2 x 448 44.8

MCS-6 592

544 + 48

29.6

27.2

MCS-5

8PSK

448 22.4

MCS-4 352 17.6

MCS-3 296

272 + 24

14.8

13.6

MCS-2 224 11.2

MCS-1

GMSK

176 8.8

Among which, 544+48 and 272+24 means valid bits plus additional bits.


Feature Description


Figure 23-2 Rate comparison between GPRS single channel and EDGE single channel

23.2.5 Link Quality Control

Link quality control refers to improving the quality of link by adjusting the modulation and coding scheme to be adapted to the radio environment during the data transmission.

EDGE adopts a high efficient link quality control algorithm. The algorithm defines two link quality control modes:

link adaptation (LA)

Incremental Redundancy (IR)

The principle of LA is as follows:

Retransmit the original data block. The receiving side needs not to store the error data block.

The principle of IR is as follows:

Step 1 Without considering the radio environment, transmit the data through the coding scheme with high speed, weak protection ability first.

Step 2 If the data is accepted incorrectly, retransmit the additional coding information.

Step 3 The receive party combines the new information and history information

Step 4 The receive party decodes the combined information.



Step 5 Repeat the above steps till the decoding succeeds.

----End

For the uplink data transmission, the system notifies the MS to use the IR mode by indicating "RESEGMENT=0" in the uplink resource allocation message by default.

The IR mode reacquires that the MS has enough memory to store the history information. If the memory is not enough, the system notifies the MS by indicating " RESEGMENT=1" in the uplink response message.

For the downlink data transmission, when the MS memory is not enough, the MS notifies the network side through the downlink response message DOWNLINK ACK/NACK that "MS OUT OF MEMORY". Thus, the network side cannot use the IR mode in the downlink.

23.2.6 Dynamic Additional Sub-TS

The rate of the timeslot in the Abis interface is 16 kbit/s. If EDGE function is used, the rate can reach 59.2 kbit/s.

The rate is improved through software method. That is, map multiple timeslots of Abis interface to one traffic channel, and then assemble and disassemble the timeslots in the transmit and receive end respectively.

The dynamic additional sub-timeslot function in EDGE is the same as that in GPRS. In the GPRS, each PDCH can only have one additional timeslot. In the EDGE, each PDCH can have three sub-timeslots.

23.2.7 EDGE Handover Algorithm

EDGE handover algorithm is a special algorithm developed by Huawei. The basic principle is as follows:

When a circuit service (CS) user accesses to the EDGE network, hand over the CS user to other network that provides CS service unconditionally after a fixed period.

With the EDGE handover algorithm, you can add a dedicated network to provide EDGE or GPRS service on the current CS network. When the MS switches on, it registers to and resides in the EDGE network.

Because the EDGE network needs to provide CS service, the EDGE network must have enough TCH channels. Thus it can hold the access of CS service and then hand over the CS users to the CS network.

When a MS initiates a CS call, the call is accessed to the EDGE network, and then be hand over to dedicated CS network after several seconds (the waiting time is set in the EDGE handover algorithm).

When the call ends, the MS returns to the EDGE network. When the MS initiates a GPRS or EDGE service call, the EDGE network provides the service for the MS directly.


Feature Description


The EDGE handover algorithm requires planning the cell reselection parameter reasonably to make the MS reside in the EDGE after switch-on. If a cell is configured to support the EDGE handover algorithm, the cell cannot be the neighbor cell of anther cell. Otherwise, the pingpang handover between the two cells occurs.

When you use the EDGE handover algorithm to set up an overlapped network, all the MSs reside in the EDGE network first. When the call begins, the MSs are handed over out. When the call ends, the MSs return to the original cell. Thus, the traffic in the A interface is very heavy. Pay attention to the planning of the A interface capacity.

23.3 Function Configuration

23.3.1 Configuration Process

To open the EDGE function, do as shown in Table 23-4.

Table 23-4 Configure the EDGE function

Step Configuration sequence Dynamic configuration Operation

1 Configure the TRXs to support the EDGE function

BTS/Modify Board Type

2 Configure idle timeslot to the BTS BTS/ Configure Site Idle TimeSlot

3 Configure the cell to support GPRS and EDGE

Cell/Modify GPRS Function

4 Configure whether the cell support the EDGE handover algorithm according to the actual requirement

Cell/Modify Cell's Handover Parameter

For details, see M900/M1800 BSC data configuration Manual –Dynamic Configuration

When configure idle timeslot for the BTS, you need to calculate the number of PDCH and the number of idle timeslot of each PDCH according to the network planning. Then you can calculate the number of idle timeslots each cell needs and then calculate the number of idle timeslot all the cells of the BTS need.



23.3.2 Parameter

Table 23-5 lists the parameters related to EDGE function.

Table 23-5 Parameters related to EDGE function

Name Unit Range Default Description

TRX Board type - - - If the PDCH of a TRX is to provide EDGE service, the TRX must be configured as RETR or DETR.

Support EDGE - 0, 1 0 Determines whether the cell supports EDGE or not.

Cell 8PSK modulation power attenuation level

0.2dB 0–50 0 If the BCCH of a cell is EDGE TRX, you need to configure the timeslot 7 of the BCCH TRX to attenuate and the attenuation value is 50 levels. Each level attenuates by 0.2db. The specific level is decided by this field. The attenuation level of other timeslots of the main BCCH carrier is decided by the carrier’s “8PSK modulation power level.

8PSK modulation power attenuation level

0.2dB 0–50 0 This value controls the power attenuation level of the timeslot that uses 8PSK modulation on the EDGE carrier.

EDGE HO allowed

- 0, 1 - Whether it initiates EDGE handover algorithm.

EDGE HO min time (s)

- 3–60 3 When the system allows EDGE handover, this value decides for how long to execute.

23.3.3 Typical Cases

A cell has two TRXs, TRX 0 and TRX 1. Among the timeslots of TRX 0, timeslot 0, timeslot 1 and timeslot 2 are configured as BCCH, SDCCH/8 and static PDCH. Timeslot 3 and timeslot 4 are configured as dynamic PDCH. Other timeslots are configured as full rate TCH.

Step 1 Configure the type of TRX 3 as RETR (configure the TRX 1 according to the actual situation).


Feature Description


Figure 23-3 Configure the type of EDGE TRX



Figure 23-4 Configure the type of EDGE TRX

Configure nine idle timeslots to the BTS that the cell resides in, as shown in Figure 23-5 and Figure 23-6.

Suppose other cells of the BTS do not support GPRS function. Because the BTS can have three PDCH at most, when all the PDCHs use the MCS-9 coding scheme, each PDCH needs three idle timeslots, the BTS needs nine idle timeslots.


Feature Description


Figure 23-5 Set BIE Property



Figure 23-6 Port Idle Timeslot Assignment

Step 2 Set the “Support for EDGE”. Set the “Cell 8PSK Level” according to network planning, as shown in Figure 23-7.


Feature Description


Figure 23-7 Configure the type of EDGE Cell

Step 3 As shown in Figure 23-8, set the value of “TRX 8PSK Level”.



Figure 23-8 TRX Property[No.5 TRX]

Step 4 Configure “EDGE HO Allowed” as : “No”, “EDGE HO Min Times(S) ” as default value, As shown in Figure 23-9.


Feature Description


Figure 23-9 Cell Handover Data

----End

23.4 Maintenance Information

23.4.1 Related Alarm

None

23.4.2 Related Traffic Statistic

Table 23-6 lists the traffic statistic items related to EDGE function.

Table 23-6 Performance indexes related to EDGE function

No. Performance index

1 Attempted Handovers for EDGE

2 Configured static EDGEs



No. Performance index

3 Configured Dynamic EDGEs

4 Average available EDGEs

5 Max num. of availabled EDGE

6 Min num. of availabled EDGE

For details, see M900/M1800 BSC Traffic Statistic Manual.

Documents

59754961-23-EDGE-Function.pdf