Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-12-23
2003-06-10
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S063300, C370S433000, C370S528000
Reexamination Certificate
active
06577862
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to telecommunications, and more specifically, to transmitting comfort noise across a mobile communications network, such as a third generation mobile system.
BACKGROUND OF THE INVENTION
System Background
As terminal devices (also called mobile communication devices), such as mobile phones, Personal Digital Assistants (PDAs), and Mobile Computing Devices (PCDs), for example, continue to proliferate, mobile communications network providers are seeking to provide economical networks and radio protocols to deliver seamless service across multiple networks. Third generation mobile systems (3G systems), such as the Universal Mobile Telecommunications Systems (UMTS, now known as INT-2000), Mobile Broadband Systems (MBS), Wireless Local Area Networks (WLAN), and Global System for Mobile Communications (GSM) derivatives, for example, address the increasing demand for mobile communication services.
FIG. 1
(Prior Art) illustrates a generic 3G system of a GSM-type mobile communications network that incorporates both a mobile phone air interface and a satellite-phone air interface. Though the 3G system of
FIG. 1
is illustrated as a GSM system, it should be understood that the 3G system architecture illustrated in
FIG. 1
generally applies to any 3G system. In addition, though much of the following discussion is directed at unidirectional information flow (from a mobile phone to another terminal device), it should be understood that the flow of information may also take place in the opposite direction from that discussed.
Accordingly, a mobile phone
110
, which could be any terminal device, is shown in communication with an antenna
114
across an air interface. Communications take place across the mobile phone air interface in a first channel
112
(and an optional second channel
116
) which carries information, such as sound or data, between the mobile phone
110
and the antenna
114
as a data unit contained in a time slot
118
. Then communications traveling through the antenna
114
pass to a Base Station (BS)
120
(which is also known as a Base Transceiver Subsystem, or BTS).
Similarly, a satellite-phone
170
uses a first channel
172
a
to transmit and receive information in a timeslot
178
a
, across the satellite-phone air interface, to or from a satellite
174
. An optional second channel
176
a
is shown to illustrate that availability of multi-channel communications. The satellite
174
is one of a network of satellites that orbit the Earth, typically in a geosynchronous orbit. The satellite
174
provides for communication, perhaps by communicating with a second satellite (not shown), with the base station
122
via a first channel
172
b
and/or second channel
176
b
, and transfers information in a timeslot
178
b
. Although
FIG. 1
illustrates communication occurring across the air interfaces in a single timeslot and in a single channel, it should be understood that communication in a 3G system may use multiple timeslots in a single channel, single timeslots in multiple channels, or multiple timeslots in a plurality of channels.
Traditionally, in a mobile communications network, the transfer of control commands (the pathway of which is called a control plane), and the transfer of user voice or data (the pathway of which is called a user plane), have occurred through the same transmission path and devices. However, one distinguishing characteristic of some implementations of third generation mobile communication systems is the physical separation of the control plane from the user plane. Accordingly, the connections which comprise the control plane are shown as dotted lines, such as a dotted line
180
, which connects base station
120
with a control node
140
through a Radio Network Controller (RNC)
132
. Likewise, the connections that comprise the user plane are shown as solid lines, such as a solid line
186
, which connects the base station
120
with a media gateway
130
which in 3G will be a Transmission Control Node (TCN)
130
.
Accordingly, the devices and connections existing on the land-based portion of the mobile communications network (called the Public Land Mobile Network, or PLMN) which transfer voice, data, or video information (collectively, “information”) between terminal devices define a user plane. Though the following discussion is directed at unidirectional information flow (from the mobile phone
110
to another terminal device), it should be understood that the flow of information also takes place in the opposite direction from that discussed. Thus, the user plane of
FIG. 1
is defined by the route information travels from the antenna
114
, through the BS
120
, and on to the media gateway
130
. The user plane continues from the media gateway
130
to a core transport network
150
that passes information onto a media gateway associated with the other terminal device. For example, if the other terminal device were the satellite-phone
170
, the media gateway base station controller combination MGW/BSC
138
, and the second base station
122
would further define the user plane. A control plane is similarly defined by the devices that execute the control commands in a PLMN, and the pathway the control commands travel from device to device in the PLMN.
To control the transfer of information through the third generation mobile system, the control node (CN)
140
[which is associated with a Mobile Switching Center (MSC) in a second generation system, or, as shown here, is a UMSC (UMTS Mobile Switching Center) server in 3G GSM] communicates with the base stations
120
,
122
, as well as the media gateways
130
,
132
,
134
,
136
and MGW/BSC
138
. Thus, the UMTS server
140
directs control commands traditionally associated with a control channel signal in second generation and first generation mobile communications systems. By separating the control plane and the user plane, user data can be transferred more efficiently between media gateways, and the control plane can be separately configured for Quality of Service and security. Thus, 3G systems employing this architecture increase flexibility and transmission efficiency in the transport network.
Though the third generation mobile system of
FIG. 1
is illustrated as a 3G Global System for Mobile Communication (GSM), it should be understood that the 3G system architecture illustrated in
FIG. 1
generally applies to any third generation mobile system. Thus, while the media gateway
130
will be a Base Station Control (BSC) in second generation GSM, it will be a Radio Network Controller (RNC) or Transmission Control Node (TCN) in UMTS.
Channel Communications and Transport Network Communications
In GSM, sound communications (or hereinafter, “voice communications”) pass across an air interface in at least one channel, in a discreet time unit known as a frame. Each frame is subdivided into a number of smaller discrete time units, known as timeslots. For example, in GSM, a single frame is subdivided into eight timeslots. Each timeslot is further divided in time into bit slots, and the bit slots are organized so that the time slot can accommodate two words of 57 bits each, as well as other bits that are needed for the transmission of the words. Similar methods of time division as well as frequency division are used across the air interfaces associated with other mobile communications networks.
In operation, to provide for predictable communication, each mobile phone call is assigned at least one time slot in a frame. However, to improve communication quality or throughput, multiple timeslots (in a single frame) in a single channel, a single timeslot in multiple channels, or multiple timeslots in a plurality of channels may be allocated to a communication.
A collection of bits representing voice communication, whether organized as a word or other assemblage, is referred to as a voice data unit. Typically, when transferring voice communications, voice samples (or data units) arriving from a mobile phone are interleaved and extr
Davidson Lee
Hameleers Heino
Hundscheidt Frank
Valentine Eric
Cong Le Thanh
Ericsson Inc.
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