MExE Quality of Service Standards

So the software at the Application layer in the sender’s device has to talk to the software
at the Application layer in the receiver’s device. To do this, it must use protocols
to move through the intermediate layers and must interact with hardware—certainly
at Layer 1, very likely at Layer 2, probably at Layer 3, and possibly at Layer 4.
MExE (the Mobile Execution Group) is a standards group within 3GPP1 working on
software/hardware standardization. Its purpose is to ensure that the end-to-end communication,
described here, actually works, with a reasonable amount of predictability.
MExE is supposed to provide a standardized way of describing software and
hardware form factor and functionality, how bandwidth on demand is allocated, and
how multiple users (each possibly with multiple channel streams) are multiplexed
onto either individual traffic channels or shared packet channels.
MExE also sets out to address algorithms for contention resolution (for example,
two people each wanting the same bandwidth at the same time with equal priority
access rights) and the scheduling and prioritizing of traffic based on negotiated quality
of service rights (defined in a service level agreement). The quality of service profile
subscriber parameters are held in the network operator’s home location register (the
register used to support subscribers logged on to the network) with a copy also held in
the USIM in the subscriber’s handset. The profiles include hardware and software
form factor and functionality, as shown in the following list:
Class mark hardware description. Covers the vendor and model of handset and
the hardware form factor—screen size and screen resolution, display driver
capability, color depth, audio inputs, and keyboard inputs.
Class mark software description. Covers the operating system or systems,
whether or not the handset supports Java-based Web browsers (the ability to
upload and download Java applets), and whether the handset has a Java Virtual
Machine (to make Java byte code instructions run faster).
Predictably, the result will be thousands of different hardware and software form
factors. This is reflected in the address bandwidth needed. The original class mark
(Class Mark 1) used in early GSM handsets was a 2-octet (16-bit) descriptor. The class
mark presently used in GSM can be anything between 2 and 5 octets (16 to 40 bits).
Class Mark 3 as standardized in 3GPP1 is a 14-octet descriptor (112 bits). Class Mark 3
is also known as the Radio Access Network (RAN) class mark. The RAN class mark
includes FDD/TDD capability, encryption and authentication, intersystem measurement
capability, positioning capability, and whether the device supports UCS2 and UCS4. This means that it covers both the source coding, including MPEG4 encoding/
decoding, and channel coding capability of the handset. Capability includes such
factors as how many simultaneous downlink channel streams are supportable, how
many uplink channel streams are supportable, maximum uplink and downlink bit
rate, and the dynamic range of the handset—minimum and maximum bit rates supportable
on a frame-by-frame basis.
MExE is effectively an evolution from existing work done by the Wireless Application
Protocol (WAP) standard groups within 3GPP1.