Multiplex communications – Data flow congestion prevention or control – Flow control of data transmission through a network
Reexamination Certificate
2000-01-05
2004-01-27
Pham, Chi (Department: 2667)
Multiplex communications
Data flow congestion prevention or control
Flow control of data transmission through a network
C370S522000, C709S232000, C455S445000, C710S029000
Reexamination Certificate
active
06683851
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The invention relates to communication systems. More particularly, the invention relates to communication of digital data over a shared link.
II. Description of the Related Art
FIG. 1
is an exemplifying embodiment of a terrestrial wireless communication system
10
.
FIG. 1
shows three remote units
12
A,
12
B and
12
C and two base stations
14
. In reality, typical wireless communication systems may have many more remote units and base stations. In
FIG. 1
, the remote unit
12
A is shown as a mobile telephone unit installed in a car.
FIG. 1
also shows the portable computer remote unit
12
B and the fixed location remote unit
12
C such as might be found in a wireless local loop or meter reading system. In the most general embodiment, the remote units may be any type of communication unit. For example, the remote units can be hand-held personal communication system (PCS) units, portable data units such as a personal data assistant, or fixed location data units such as meter reading equipment.
FIG. 1
shows a forward link signal
18
from the base stations
14
to the remote units
12
and a reverse link signal
20
from the remote units
12
to the base stations
14
.
In the discussion that follows, to aid in illustration, the invention is described with reference to a commonly known, wireless link industry standard and the accompanying data standards which have been developed for use in conjunction with that standard. In fact, the generic principles of the invention can be directly applied to many environments. The discussion that follows assumes operation in accordance with the system described in TIA/EIA/IS-95-A published by the Telephone Industry Association entitled “Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” commonly referred to as IS-95.
In addition, a family of data transmission standards compatible with IS-95 have been adopted to provide data services over a wireless link. Examples of data services are FAX, digital file transfer, network access, standard modem functions and the like. An early standard is described in TIA/EIA/IS-99 entitled “Data Services Option Standard for Wideband Spread Spectrum Digital Cellular System.” Another more recent standard is described in TIA/EIA/IS-707 entitled “Data Service Options for Spread Spectrum Systems.” The IS-99 and IS-707 define radio link protocols which allow the remote unit to emulate standard modem functions. In addition to these two standards, TIA/EIA/IS-657 entitled “Packet Data Services Option for Wideband Spread Spectrum Systems” defines a radio link protocol which allows the remote unit to pass packetized data over the wireless link.
FIG. 2
is a block diagram of a standard remote unit
36
which comprises voice and data functionality. A central control unit
26
controls all of the functions needed for wireless voice and data services in addition to personal interface management (PIM), such as voice recording and play back. For example, the central control unit
26
may receive a telephone number entered by a user via a keypad
34
and command a communication unit
24
to establish a voice call to that telephone number.
The communication unit
24
provides the actual wireless voice and wireless data access capability in addition to other inherent functions such as voice playback, translation of wireless voice data to digital format for storage by the central control unit
26
and indications of wireless access status. In one embodiment, the communication unit
24
communicates with a base station according to IS-95. The communication unit
24
exchanges audio signals with a earpiece/microphone unit
28
.
A display
30
is used to provide visual information to the remote unit user. The central control unit
26
passes information received from both the keypad
34
and the communication unit
24
to the display
30
. For example, the central control unit
26
receives information about the current signal level received from the base station and passes the information to the display
30
where it is displayed for the user—whether or not a wireless channel has been established. In addition, the central control unit
26
passes information concerning the current wireless status to the display
30
during a call. For example, the display
30
may indicate that the channel is connected, disconnected or in the process of being connected. When an incoming call is detected by the communication unit
24
, the central control unit
26
enables a ringer
36
to alert the user.
In one embodiment, the central process
26
passes digital data between the communication unit
24
and an external source (not shown) directly. The transfer of data to and from the external source is accomplished by way of a external serial connector
32
. For example, a lap top or personal computer running a data service or a diagnostic monitor may be attached to the remote unit
36
via the external serial connector
32
. In another embodiment, the central control unit
26
passes serial data directly to and from a lap top or personal computer without involvement from the communication unit
24
.
In addition to cellular phones, other forms of portable electronics have become prevalent in the business and personal sectors. One device which is becoming increasingly popular is the personal data assistant (PDA). A PDA is like a miniature palm-held computer which allows the user to perform basic computer functions such as word processing, scheduling, spreadsheets and other such functions.
In order to increase the utility of a PDA, wireless functionality has been introduced to the PDA. When PDA and wireless functions are combined into a single unit having a common palm-sized casing, the resulting unit is referred to as a smartphone. A smartphone may send and retrieve e-mail, access the Internet, act as a pager and cellular telephone and provide many other wireless functions.
When the functionality of a remote unit is combined with the functionality of a PDA, typically a single display is used to provide information concerning the wireless link and concerning the operations of the PDA. For example, the same screen which is used to display the dialed digits and the received signal strength is also used to display e-mail messages and soft key functions. Therefore, the central processor in the remote unit must communicate with a central processor of the PDA to provide such information for display. In addition to wireless status, other functionality in the smartphone may require the transfer of information between the two portions of the smartphone. For example, the smartphone may incorporate an answering machine or voice-memo function. The digital voice samples may be stored in memory associated with the PDA portion of the smartphone. The samples are passed to the remote unit portion of the smartphone when accessed by the user so that the vocoder and speaker portion of the remote unit may be used to replay the message. In a like manner, when an incoming message is recorded, digital voice samples must be passed from the remote unit portion of the smartphone to the PDA portion.
When building a remote unit module for integration into a smartphone, it is advantageous to avoid extensive modification of the existing remote unit design. In this way, development costs as well as on-going production costs may be reduced due to economies of scale.
When an electronic device is designed such that a first plurality of modules communicate with a second plurality of modules over a common data link, some means of controlling the flow of data and regulating access to the common data link must be used. In some environments, it is advantageous if the modules themselves operate transparent to the use of the common data link. For example, the modules may be designed as part of an application specific integrated circuit (ASIC) which is configured to be directly connected to a set of modules rather than connected over a common data link. In order to avoid re-des
Scott Clifton Eugene
Willkie James J.
Brown Charles D.
Cheatham Kevin T.
Pham Chi
Qualcomm Incorporated
Qureshi Afsar M.
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