Telecommunications – Radiotelephone system – Auxiliary data signaling
Reexamination Certificate
2000-07-13
2004-08-03
Kincaid, Lester G. (Department: 2686)
Telecommunications
Radiotelephone system
Auxiliary data signaling
C370S466000
Reexamination Certificate
active
06771975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wireless application protocol, and more particularly, to a method of processing data to transmit in a wireless application protocol for wireless applications using Unstructured Supplementary Service Data (USSD).
2. Description of the Related Art
The worldwide market for mobile telecommunication terminals, which provide convenient communication, is rapidly expanding. The technological era of mobile telecommunication terminals which began with analogue cellular phones has seen the introduction of digital cellular phones, and now, personal communications services (PCS) phones. In line with the development of mobile telecommunications technologies, it has become possible to access data networks such as the Internet via a mobile telecommunications terminal. Accordingly, diverse wireless application services, such as Internet content services and voice services are now being offered by mobile telecommunications networks.
Due to the characteristics of devices, however, mobile telecommunications terminals have many limitations in available resources, for example due to power supply capacity, the size and visibility of a display, transmission rate, and capacities of a processor and a memory. Therefore, compared to a protocol supporting access to the Internet via a computer for using web services, protocols supporting use of diverse wireless application services from a mobile telecommunications terminal are designed in relatively simple form, considering the limited resources of the mobile telecommunications terminal.
Among protocols which have been standardized or are being standardized in order to support the use of wireless application services via a mobile telecommunications terminal, one of the leading protocols is Wireless Application Protocol (WAP) proposed by WAP Forum.
WAP has a configuration similar to that of the protocol used for computers. For example, WAP uses a Wireless Markup Language (WML) in the presentation layer, a substitution for a HyperText Markup Language (HTML), and a Wireless Session Protocol (WSP) in the session layer, similar to a HyperText Transfer Protocol (HTTP). WAP uses a Wireless Transport Protocol (WTP) which is an integration of a Transport Control Protocol (TCP) and an Internet Protocol (IP), or a Wireless Datagram Protocol (WDP) which is an integration of a User Datagram Protocol (UDP) and the IP, in its transport and network layer.
Contrary to other bearers applied to the WAP, however, if the Global System for Mobile Communication (GSM) USSD is used as a lower bearer, the WAP must include an additional layer. That is, a USSD Dialogue Control Protocol (UDCP) layer is used as a WAP adaptation layer.
FIG. 1
is a schematic diagram showing the protocol stack of the WAP
100
when the GSM USSD is used as a lower bearer.
Included in
FIG. 1
is a Wireless Application Environment (WAE) layer
110
, which provides an integrated wireless application environment independent of the kinds of network or lower bearer. The WAE includes a WML which is a display language, a WML script which is a script language, and a Wireless Telephone services application program interface and Architecture (WTA) which is an application program interface for call services. A WSP layer
120
provides session services to upper layers and is primarily based on the HTTP.
A WTP layer
130
, which is a transport layer for wireless application services, plays the roles of existing TCP(UDP)/IP and Point-to-Point Protocol (PPP) to ensure independency of the kinds of underlying network. The WDP layer
140
is a kind of WTP using a datagram (also called WTP/D), and provides a connection-less, unreliable data service method.
A UDCP layer
150
is an adaptation layer used to control an additional USSD dialogue for a lower GSM USSD
160
bearer. The USSD layer
160
supports transmission of text between mobile telecommunications terminals through wireless telecommunications networks, and is used for a variety of supplementary services which are not defined in the GSM specification.
The GSM specification is one of the standard specifications for wireless communications in digital cellular mobile telecommunications networks. The GSM specification is based on a Time Division Multiple Access (TDMA) technique, and is mainly used in the U.S. and European countries. Meanwhile, mobile telecommunications services in Korea are provided through a Code Division Multiple Access (CDMA) technique instead of the GSM.
The packet structure in each layer will now be described by focusing on the WDP and UDCP layers.
FIG. 2
is a schematic diagram showing the packet structure, that is, a Protocol Data Unit (PDU), in the WDP and UDCP layers in WAP's protocol stack for the GSM USSD of FIG.
1
.
As illustrated in
FIG. 2
, user data
200
in an upper layer, for example the WSP layer, is encapsulated without any change into a data field
200
a
in a PDU
210
of the WDP layer, and then added to a WDP header which is an information element (IE) having information about the user data field
200
a
, forming an entire PDU
210
of the WDP layer. In
FIG. 2
, the IE includes an IE_PORT field
212
which has information on a port, which is an access point to the WDP layer from the upper layer, and an IE_SAR field
214
which has information on Segmentation And Reassembly (SAR).
SAR is a technique of segmenting the data received from an upper layer and then forwarding the segmented data, or reassembling received segmented data and then passing the reassembled data to an upper layer when the size of data that can be transmitted through a lower telecommunications network is limited.
Next, the PDU
210
of the WDP layer is encapsulated unchanged into a user data field
210
a
in the PDU
220
of the UDCP layer, and then a UDCP header is added thereto to form a UDCP PDU
220
. The UDCP header includes an IE_UDCP field
226
which has dialogue control information, an UDH_LEN field
224
which has information on the length of a user data header, and a TOT_LEN field
222
which has information on the length of the UDCP PDU
220
in the UDCP layer. In
FIG. 2
, the user data header includes the IE_UDCP field
226
, and the IE_PORT field
212
and the IE_SAR field
214
which are included in the WDP layer.
The protocol operation in the WDP and UDCP layers according to the conventional WAP will now be described focusing on the aspect of memory management.
FIG. 3
is a schematic diagram showing the protocol operation in WDP and UDCP layers in wireless application protocols for wireless application services using the existing USSD, from the viewpoint of memory management.
As illustrated in
FIG. 3
, when user data
301
and
302
of an upper layer passed down to the WDP layer along the WAP protocol stack, the WDP layer sequentially stores data
301
a
and
302
a
in a WDP buffer
310
, adds WDP headers to the user data, and then passes data with headers,
311
and
312
, to the UDCP layer. If the size of the user data
301
a
and
302
a
stored in the WDP buffer
310
is bigger than that of a transmission unit of the lower telecommunication network USSD, the WDP layer adds a WDP header to each segment after carrying out the SAR.
The UDCP layer sequentially stores the data
311
and
312
transferred from the WDP layer in a UDCP buffer
320
and transmits the data
321
and
322
, to which the UDCP headers have been added, from storage in a UDCP buffer
320
through the USSD layer to a destination node at an appropriate point in time, that is, when a dialogue control is set up.
Because the WAP is a protocol that supports wireless application services using a mobile telecommunications terminal, the WAP needs to be designed to minimize memory use in consideration of limited resources of the mobile telecommunication terminal.
In conventional methods, however, when a lower bearer is the USSD, additional memory is needed in the UDCP layer in addition to that of the WDP layer, because of a separate UDCP adaptation layer for the USSD dialogue contro
Kincaid Lester G.
Mehrpour Naghmeh
Samsung Electronics Co,. Ltd.
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