18. 18
LTE frequency bands
➢ 3GPP Release 8 defines 5 LTE user
equipment categories depending on
maximum peak data rate and MIMO
capabilities support [1]
➢ CAT 3, CAT 4 modules took up a dominant
share of cellular market so far
➢ Some new modules start to support CAT6
LTE Category
➢ The definition is in 3GPP TS 36.101
➢ The available band might be different
in different country
Get Proper Cellular Module
Module PIN definition
➢ Make sure the PIN definition between
slot and module are the same
23. 23
Control Path Protocol Data Path Interface
1. AT commands
2. QMI (after kernel v3.4 )
3. MBIM (after kernel v3.8)
1. ppp (ttyUSB or cdc-acm)
2. RNDIS (cdc-ecm)
3. QMI (cdc-wdm)
4. MBIM (cdc-mbim)
* This table only lists information which I have handled
24. 24
Control Path Protocol Data Path Interface
1. AT commands
2. QMI (after kernel v3.4 )
3. MBIM (after kernel v3.8)
1. ppp (ttyUSB or cdc-acm)
2. RNDIS (cdc-ecm)
3. QMI (cdc-wdm)
4. MBIM (cdc-mbim)
25. 25
AT commands - Hayes command set [2][3]
❏ Developed by Dennis Hayes
❏ A series of short text strings which can be combined to produce commands for operations
• dialing
• hanging up
• changing the parameters
❏ “AT” meaning 'attention’
26. 26
AT commands - Hayes command set [2][3]
Standard format of AT commands
AT+
Proprietary format of AT commands
AT!, AT^ or AT$ etc..
28. 28
Control Path Protocol Data Path Interface
1. AT commands
2. QMI (after kernel v3.4 )
3. MBIM (after kernel v3.8)
1. ppp (ttyUSB or cdc-acm)
2. RNDIS (cdc-ecm)
3. QMI (cdc-wdm)
4. MBIM (cdc-mbim)
29. 29
Dial-up by using PPP [5]
Not a Recommended way
6+ steps to dial up with ppp
1. Install the packages in Debian/ Ubuntu
➢ apt-get install netbase ifupdown ppp
2. Create a file /etc/ppp/peers/gprs with this
content
3. Edit /etc/ppp/chap-secrets
4. Edit /etc/ppp/pap-secrets
5. Edit /etc/network/interfaces
6. ifup gprs
7. !@#$%^&*()_
ref: https://c1.staticflickr.com/5/4150/5067471752_1fa8a4ab15.jpg
33. 33
Control Path Protocol Data Path Interface
1. AT commands
2. QMI (after kernel v3.4 )
3. MBIM (after kernel v3.8)
1. ppp (ttyUSB or cdc-acm)
2. RNDIS (cdc-ecm)
3. QMI (cdc-wdm)
4. MBIM (cdc-mbim)
serial interface
Non serial interface
34. 34
Ethernet Networking Control Model
CDC_ECM + RNDIS - Ethernet over USB [16]
Virtual
Interface
RNDIS
Virtual
Interface
…
Cellular Module – Router mode
IPTABLES - NAT
IP Stack
DHCPDNS➢ RNDIS - Proprietary protocol developed
by Microsoft
➢ “virtual Ethernet” functionality
➢ Support USB high speed
○ Not suitable for the module which
are for more than CAT 6
35. 35
Ethernet Networking Control Model
CDC_ECM + RNDIS - Ethernet over USB
Virtual
Interface
RNDIS
Virtual
Interface
…
Cellular Module – Router mode
IPTABLES - NAT
IP Stack
DHCPDNS
Virtual
Interface
RNDIS
Virtual
Interface
…
Cellular Module – Bridge mode
IPTABLES - NATIP Stack
DHCPDNS
47. 47
Control Path Protocol Data Path Interface
1. AT commands
2. QMI (after kernel v3.4 )
3. MBIM (after kernel v3.8)
1. ppp (ttyUSB or cdc-acm)
2. RNDIS (cdc-ecm)
3. QMI (cdc-wdm)
4. MBIM (cdc-mbim)
➔ extends cdc-ncm (Network Control Model)
48. 48
Mobile Broadband Interface Model (MBIM)
◆USB-IF Standard (Extends NCM)
• Microsoft
• Intel
• HP
• …
◆Linux Kernel 3.8
• cdc_mbim
◆Binary protocol
◆Raw IP
◆MBIM could embedded different protocols
• QMI
• …
49. 49
Mobile Broadband Interface Model (MBIM)
➢ MBIM extends the NCM as a protocol with
the difference that devices transfer raw IP packets
instead of packets with 802.3 headers
➢ NCM
○ 802.3 headers
➢ NCM/ MBIM
○ Raw IP
○ Control path
50. 50
Mobile Broadband Interface Model (MBIM)
Device Driver Owner User-space
cdc_mbim Open Source Community libmbim (freedesktop.org)
umbim (openWRT)
55. 55
Use command “dmesg” to find out the
idVendor and idProduct of cellular module.
Use command “grep -r "1199" drivers/net/usb/” to
find out which driver does it use.
Lazy is the greatest motivation behind progress
56. 56
Hands-on Experience – FAQ
Dial-up failed !
Check steps one by one
• Check the band of SIM card is matched with cellular module
• Check SIM card is ready or not (Make sure PIN code is correct)
• Check cellular signal is good enough
• Make sure SIM card's supporting band is the same with the cellular module
• Make sure the firmware of cellular module is the same with the ISP
• Make sure cellular module is connected properly to your antenna (MAIN/ AUX)
• Make sure the mode of module firmware is configured properly
• Make sure wireless disable function is OFF
57. 57
Hands-on Experience – FAQ
My connection is disconnected !
Check steps one by one
• Check cellular signal from base station
• Make sure cellular module is not in idle mode
• Make sure MTU is configured properly
60. 60
Hands-on Experience – FAQ
Make sure MTU is configured properly
This forces the packet to be fragmented, and the fragmented packets are not be re-assembled.
M2M IoT Network Usage Guidelines [25]
61. 61
Conclusion
Enable LTE-A module require more fundamental
knowledge
➢ Band, carrier, firmware, antenna, etc…
1
2
3
Future Prospects
➢ MBIM
➢ 3GPP Rel. 12
○ LTE-U
➢ 3GPP Rel. 13
○ LTE-LAA
Fault tolerance mechanism
➢ We cannot control status of base station and carrier