Wireless communications device with a state model

Details Wireless communications device with a state model Wireless communications device with a state model

2001-07-04

2004-09-28

Patel, Ajit (Department: 2664)

Multiplex communications

Communication over free space

Combining or distributing information via time channels

C370S469000, C370S310000

Reexamination Certificate

active

06798764

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a state model for a wireless communications device. In particular, the present invention discloses a finite state machine for the wireless device that includes a reset/suspend state.
2. Description of the Prior Art
Technological advances have moved hand in hand with more demanding consumer expectations. Devices that but ten years ago were considered cutting edge are today obsolete. These consumer demands in the marketplace spur companies towards innovation. The resulting technological advances, in turn, raise consumer expectations. Presently, portable wireless devices, such as cellular telephones, personal data assistants (PDAs), notebook computers, etc., are a high-growth market. However, the communications protocols used by these wireless devices are quite old. Consumers are demanding faster wireless access with greater throughput and flexibility. This has placed pressure upon industry to develop increasingly sophisticated communications standards. The 3
rd
Generation Partnership Project (3GPP™) is an example of such a new communications protocol.
The 3GPP™ standard utilizes a three-layered approach to communications. Please refer to FIG.
1
.
FIG. 1
is a simplified block diagram of the prior art communications model. A prior art wireless system includes a first device
20
and a second device
30
, both of which are in wireless communications with each other. As an example, the first device
20
may be a mobile unit, such as a cellular telephone, and the second device
30
may be a base station. An application
24
on the first device
20
needs to send data
24
d
to an application
34
on the second device
30
. The application
24
connects with a layer
3
interface
23
(termed the radio resource control (RRC)), and passes the data
24
d
to the layer
3
interface
23
. The layer
3
interface
23
uses the data
24
d
to form a layer
3
protocol data unit (PDU)
23
p
. The layer
3
PDU
23
p
includes a layer
3
header
23
h
and data
23
d
, which is identical to the data
24
d
. The layer
3
header
23
h
in the layer
3
PDU
23
p
contains information needed by the corresponding layer
3
interface
33
on the second device
30
to effect proper communications. The layer
3
interface
23
then passes the layer
3
PDU
23
p
to a layer
2
interface
22
. The layer
2
interface
22
(also termed the radio link control (RLC)) uses the layer
3
PDU
23
p
to build one or more layer
2
PDUs
22
p
. Generally speaking, each layer
2
PDU
22
p
has the same fixed size. Consequently, if the layer
3
PDU
23
p
is quite large, the layer
3
PDU
23
p
will be broken into chunks by the layer
2
interface
22
to form the layer
2
PDUs
22
p
, as is shown in FIG.
1
. Each layer
2
PDU
22
p
contains a data region
22
d
, and a layer
2
header
22
h
. In
FIG. 1
, the data
23
d
has been broken into two layer
2
PDUs
22
p
. Also note that the layer
3
header
23
h
is placed in the data region
22
d
of a layer
2
PDU
22
p
. The layer
3
header
23
h
holds no significance for the layer
2
interface
22
, and is simply treated as data. The layer
2
interface
22
then passes the layer
2
PDUs
22
p
to a layer
1
interface
21
. The layer
1
interface
21
is the physical interface, and does all the actual transmitting and receiving of data. The layer
1
interface
21
accepts the layer
2
PDUs
22
p
and uses them to build layer
1
PDUs
21
p
. As with the preceding layers, each layer
1
PDU
21
p
has a data region
21
d
and a layer
1
header
21
h
. Note that the layer
3
header
23
h
and layer
2
headers
22
h
are no more important to the layer
1
interface
21
than the application data
24
d
. The layer
1
interface
21
then transmits the layer
1
PDUs
21
p
to the second device
30
.
A reverse process occurs on the second device
30
. After receiving layer
1
PDUs
31
p
from the first device
20
, a layer
1
interface
31
on the second device
30
removes the layer
1
headers
31
h
from each received layer
1
PDU
31
p
. This leaves only the layer
1
data regions
31
d
, which are, in effect, layer
2
PDUs. These layer
1
data regions
31
d
are passed up to a layer
2
interface
32
. The layer
2
interface
32
accepts the layer
2
PDUs
32
p
and uses the layer
2
headers
32
h
to determine how to assemble the layer
2
PDUs
32
p
into appropriate layer
3
PDUs. In the example depicted in
FIG. 1
, the layer
2
headers
32
h
are stripped from the layer
2
PDUs
32
p
, leaving only the data regions
32
d
. The data regions
32
d
are appended to each other in the proper order, and then passed up to the layer
3
interface
33
. The layer
3
interface
33
accepts the layer
3
PDU
33
p
from the layer
2
interface
32
, strips the header
33
h
from the layer
3
PDU
33
p
, and passes the data region
33
d
to the application
34
. The application
34
thus has data
34
d
that should be identical to the data
24
d
sent by the application
24
on the first device
20
.
Please refer to
FIG. 2
in conjunction with FIG.
1
.
FIG. 2
is simplified block diagram of a layer
2
PDU
40
. The layer
2
PDU
40
has a layer
2
header
41
and a data region
45
. As noted above, the data region
45
is used to carry layer
3
PDUs
23
p
received from the layer
3
interface
23
. The layer
2
header
41
includes a data/control indicator bit
42
, a sequence number field
43
, and additional fields
44
. The additional fields
44
are not of direct relevance to the present invention, and so will not be discussed. The data/control bit
42
is used to indicate if the layer
2
PDU
40
is a data PDU or a control PDU. Data PDUs are used to carry layer
3
data. Control PDUs are generated internally by the layer
2
interface
22
,
32
and are used exclusively for signaling between the layer
2
interfaces
22
and
32
, such as the passing of reset and reset acknowledgment signals. Control PDUs are thus never passed up to the layer
3
interface
23
,
33
. The sequence number field
43
contains a 12-bit or 7-bit value that is used to reassemble the layer
2
PDUs
40
into layer
3
PDUs
33
p
. Each layer
2
PDU
22
p
is transmitted with a successively higher value in the sequence number field
43
, and in this manner the layer
2
interface
32
knows the correct ordering of received layer
2
PDUs
32
p.
Please refer to
FIGS. 3 and 4
in conjunction with
FIGS. 1 and 2
.
FIGS. 3 and 4
are state model diagrams of a prior art layer
2
interface. The prior art layer
2
interface
22
,
32
is designed as a finite state machine.
FIG. 3
depicts the state model for the layer
2
interface
22
,
32
when a reset command is performed.
FIG. 4
depicts the state model when a local suspend command is performed. Transitions between states are noted by arrows in
FIGS. 3 and 4
. Received signals associated with a state transition are noted above a horizontal line, and signals sent in response to the state transition are noted below the horizontal line. The layer
2
interface
22
,
32
includes a null state
50
, a data transfer ready state
52
, a reset pending state
54
and a local suspend state
56
. To explain these state models, the first device
20
will be used as an example. When the layer
2
interface
22
is in the null state
50
, the layer
2
interface
22
has no established wireless channel
11
with the second device
30
. The layer
2
interface
22
of the first device
20
thus cannot transmit any layer
2
PDUs
22
p
to the second device
30
. When the application
24
determines that it wishes to send the data
24
d
to the application
34
, the application
24
signals this intent to the layer
3
interface
23
. The layer
3
interface
23
then performs whatever functions are necessary to establish the channel
11
with the second device
30
. In particular, the layer
3
interface
23
sends an establish primitive to the layer
2
interface
22
. On reception of the establish primitive,

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