Wimax Network Access and Trouble Shooting

7/29/2019 Wimax Network Access and Trouble Shooting

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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

Security Level: Internal

www.huawei.com

WIMAX NETWORK

ACCESS AND

TROUBLESHOOTING



HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2

Chapter 1 NETWORK ACCESS

Chapter 2 TROUBLESHOOTING CPE

ACCESS




The ms performs DL physical

synchronization. If synch

succeeds, an indication

Is given

The MS demodulates

messages DL/UL MAP,

DCD/UCD to obtain the

UL/DL channel parameters

and keeps MAC UL/DL

synchronization

After the ms obtains UL

parameters it initializes the

ranging process. After the

ranging process succeeds,

the MS obtains basic CID

and PRIMARY CID

The MS negotiates the basic

capabilities with the BS

through the SBC-REQ?SBC-RSP

message, they negotiate

mainly parameters related

to the physical layer

and authentication

ACCESS FLOW




The MS performs

registration by

communicating with

the BS through the

REG-REQ//REG-RSP

message

The IP connection setup,

Time and date setup

and operation

parameters sending are

optional according to theprotocol. The implementation

of these phases depends

on product realization

Then the BS sends the

DSA-REQ message to

the ms and sets up thetraffic flow and assigns

it to the MS, the ms

responds with the DSA-RSP

message and Obtains the

service CID

ACCESS FLOW CONT’D




The capture above shows the actual flow as the CPE tries to

Access the WIMAX network




THE MAINTENANCE NETWORK INTERFACE

This is used to check, as well as make modificationsTo various physical layer parameters to enable access

or during troubleshooting.

There are 3 ways in which the maintenance interface can

be accessed.

•BWA

•IE

•COMMAND PROMPT




When BWA is launched, the diagram

On the left appears, making

Modifications on physical parameters

Is possible through expert login

BWA

CLICK Tools,

Expert Login

Input the username and

Password in the space

Provided, as shown below

If the CPE has not been connected to the

System, this would be displayed at the bottom

Of the BWA interface




From this expert mode,

Modifications can be made to the

Bandwidth, and frequency settings,

Also username and password

Click frequency setting to

make modifications on

Frequency settings




3 important command used when troubleshooting

Network Access

“Showss”

“Showssphy”

“Showmacdl”




INTERNET EXPLORER

Input user name

and password in

The area provided




Once the correct user name and password has been inputed

the interface shown above appears which shows the device information




Click WIMAX

Under WIMAX Status, various physical

Layer parameters can be viewed




By clicking SCAN INFO the stored DL frequency settings can be viewed




By clicking on security under WIMAX the user nameand password can be changed




From SCANSET modifications in the frequency settings

can be made.




After modifications have been made it is important to reboot the

the CPE for the modifications to take effect, this is done by clicking

DEVICE under Maintain




COMMAND PROMPT

Using command prompt, it

Is possible to telnet intoThe maintenance interface,

as shown

A username and password

would be prompted




Once access to the maintenance interface is permitted

The 3 important commands can be executed, cmd and a

Space must be included before the command




Chapter 1 NETWORK ACCESS

Chapter 2 TROUBLESHOOTING CPE

ACCESS




The main factors that cause network entry failure, are

•Interference

•Poor Coverage

•Rejection by AAA

TROUBLESHOOTING CPE ACCESS

When getting to the customers premise, the first thing to do is to execute

the 3 commands from the maintenance interface to check parameters like

RSSI, CINR and current FEC code, from this the problem can be determined.

Next, locate the position of the user on the map.




If co-channel interference

exists, the CINR is affected,

So also the AMC, and the

transmission rate. When CINRis below 10db, the CPE would

not be able to synchronize

With the down link

transmission of the BS

If the distance of the CPE is large or obstructions exist between

the CPE and the BS, the signal received by the CPE would be

Weak (RSSI), hence the CPE would not be able to receive

parameters used for UL ACQUISITION and RANGING.




How can interference be detected

Using the simple formula /RSSI/ + /CINR/ > 90,

we can determine if co-channel interference exists

The CPE has been located

On the map as shown

CPE




Firstly the cause of the co-channel interference

has to be determined, this can be done by blocking adjacent sector

carriers that are using the same frequency channel one by one until the

source of Interference is determined.

This is done using MML COMMAND on M2000

Adjacent sector carriers on

The same frequency channel




In this case there two possible solutions

•Change the azimuth or tilt on the interfering BS

•Change the azimuth of the CPE




Poor Coverage

>2km

Here the received signal (RSSI) would

Be weak, resulting in network entry

Failure. The solution would be toChange the location of the CPE to a place

Were stronger signals can be received




Rejection by AAA

Rejection of the user by

AAA also causes networkentry failure.

This could be as a result

of forgotten passwords or

Account expiration

The authentication failure

flow is shown



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