Title: Data transmission device
Abstract: In a device for data transmission having a central station and a plurality of subscribers, in addition to useful signal data phases, signaling data phases are provided for the downlink and uplink in a transmission frame (3). The signaling data phases for the downlink are divided into signaling data phases related to the central station and related to the protocol. The positions of these two signaling data phases are identified directly or indirectly by identifiers.
Patent Number: 7,023,834 Issued on 04/04/2006 to Radimirsch
| Inventors:
|
Radimirsch; Markus (Laatzen, DE)
|
| Assignee:
|
Robert Bosch GmbH (Stuttgart, DE)
|
| Appl. No.:
|
807710 |
| Filed:
|
August 27, 1999 |
| PCT Filed:
|
August 27, 1999
|
| PCT NO:
|
PCT/DE99/02685
|
| 371 Date:
|
April 17, 2001
|
| 102(e) Date:
|
April 17, 2001
|
| PCT PUB.NO.:
|
WO00/24158 |
| PCT PUB. Date:
|
April 27, 2000 |
Foreign Application Priority Data
| Oct 16, 1998[DE] | 198 47 777 |
| Current U.S. Class: |
370/349; 370/470; 370/522; 455/434; 455/515 |
| Current Intern'l Class: |
H04J 3/16 (20060101); H04B 7/00 (20060101) |
| Field of Search: |
370/280,294,328,345,349,420,458,463,465,470,522
455/422.1,434,450,509,515
|
References Cited [Referenced By]
U.S. Patent Documents
| 6016319 | Jan., 2000 | Kshirsagar et al.
| |
| 6363267 | Mar., 2002 | Lindskog et al.
| |
| 6512779 | Jan., 2003 | Vollmer et al.
| |
| 6622251 | Sep., 2003 | Lindskog et al.
| |
| 6728550 | Apr., 2004 | Bohnke et al.
| |
| Foreign Patent Documents |
| 197 26 120 | Dec., 1998 | DE.
| |
Other References
Gibson, "The Mobile Communications Handbook", 1999, Springer Verlag, Heidelberg.
Bradner; Mankin, "The Recommendation for the IP Next Generation Protocol", Online,
Jan. 1995, Retrieved from the Internet: <URL: http://hlapic.srce.hr/cgi-bin/rfc/rfc11752.txt>,
Apr. 10, 2000, p. 22, lines 15-30.
A Kramling et al., "Performance Evaluation of MAC Schemes for Wireless ATM Systems
with Centralized Control Considering Processing Delays," EPMCC, Bonn, 1997.
Karsten Brüninghaus, Markus Radimirsch, "Coarse Frame Synchronization for
OFDM-Based Wireless Communication Systems", PIMRC, Boston, 1998.
|
Primary Examiner: Hsu; Alpus H.
Attorney, Agent or Firm: Kenyon & Kenyon
Claims
What is claimed is:
1. A method for transmitting data on a common medium in a system including a
central station and a plurality of subscribers, data packets in the system being
transmitted from the central station to the subscribers (downlink) and from the
subscribers to the central station (uplink), the central station being responsible
for coordinating media access via a protocol-oriented transmission frame, the transmission
frame including a useful signal data phase and a signaling data phase for the uplink
and the downlink, the method comprising:
dividing the signaling data phase for the downlink into a signaling data phase
related to the central station and a protocol-related signaling data phase;
providing at least one identifier of a position in time of the protocol-related
signaling data phase of the downlink in the transmission frame; and
including the at least one identifier directly in the signaling data phase for
the downlink.
2. The method according to claim 1, further comprising:
announcing the position of the protocol-related signaling data phase, the position
being announced in an announcement in the signaling data phase related to the central
station, the announcement for indirectly identifying the protocol-related signaling
data phase.
3. The method according to claim 1, wherein the announcement contains a time
interval of the protocol-related signaling data phase.
4. The method according to claim 1, further comprising:
providing a subscriber-related signaling data phase at a beginning of the transmission frame.
5. The method according to claim 1, further comprising:
providing a first one of the at least one identifier immediately before the signaling
data phase related to the central station, the first one of the at least one identifier
for identifying a beginning of the transmission frame.
6. The method according to claim 1, wherein a time interval between the signaling
data phase related to the central station and the protocol-related signaling data
phase is a fixed value.
7. The method according to claim 1, further comprising:
communicating to the subscribers via the central station a time interval between
the signaling data phase related to the central station and the protocol-related
data signaling data phase, the time interval between the signaling data phase related
to the central station and the protocol-related signaling data phase being variable.
8. The method according to claim 1, wherein a time interval between the signaling
data phase related to the central station and the protocol-related signaling data
phase is filled with useful data.
9. The method according to claim 1, wherein the signaling data phase related
to the central station is at a constant distance from a beginning of the transmission frame.
10. The method according to claim 1, further comprising:
providing reference points in time for the signaling data phase related to the
central station and the protocol-related signaling data phase, the reference points
in time being located one of: i) in a beginning of a respective signaling data
phase, ii) in a middle of a respective signaling data phase, and iii) in at least
one of the at least one identifier.
11. The method according to claim 10, further comprising:
providing a first one of the at least one identifier before the signaling data
phase related to the central station and a second one of the at least one identifier
before the protocol-related signaling data phase, the first one of the identifier
and the second one of the at least one identifier being different from one another.
12. The method according to claim 11, wherein the first one of the identifier
and the second one of the identifier being different from one another regardless
of whether a position of the protocol-related signaling data phase is announced
in the signaling data phase related to the central station.
13. The method according to claim 1, further comprising:
providing the at least one identifier only before the protocol-related signaling
data phase regardless of whether a position of the protocol-related signal data
phase is announced in the signaling data phase related to the central station.
14. The method according to claim 1, further comprising:
providing an additional identifier of the transmission frame independently of
the at least one identifier.
15. A method for transmitting data on a common medium in a system including a
central station and a plurality of subscribers, data packets in the system being
transmitted from the central station to the subscribers (downlink) and from the
subscribers to the central station (uplink), the central station being responsible
for coordinating media access via a protocol-oriented transmission frame, the transmission
frame including a useful signal data phase and a signaling data phase for the uplink
and the downlink, the method comprising:
dividing the signaling data phase for the downlink into a signaling data phase
related to the central station and a protocol-related signaling data phase;
providing a first identifier of a position in time of the protocol-related signaling
data phase of the downlink in the transmission frame; and
deriving the first identifier of the position in time of the protocol-related
signaling data phase of the downlink from a second identifier, the second identifier
being provided for a position of the signal data phase related to the central station.
Description
FIELD OF THE INVENTION
The present invention relates to a data transmission device on a common medium
having a central station and a plurality of subscribers, which is controllable
by transmitting data packets from the central station to the subscribers (downlink)
and from the subscribers to the central station (uplink).
BACKGROUND INFORMATION
German Patent Application No. 197 26 120 describes a device where the central
station assumes the coordinating function for media access via a protocol-oriented
transmission frame referred to there as signaling periods. This transmission frame
contains, in addition to the useful signal data phases, signaling data phases for
the uplink and the downlink.
The method described in German Patent Application No. 197 26 120 includes the
step that the position of the downlink signaling is announced in the previous downlink
signaling. This method presents the problem that a subscriber (terminal) that wishes
to log into the communication process has no previous information regarding the
position of the downlink signaling (Broadcast Channel, BCH). Therefore, this terminal
must demodulate the transmission channel until it has found a BCH and has demodulated
the information about the position of the next BCH. Access to the transmission
channel can therefore only take place in the following transmission frame.
SUMMARY
In accordance with an example embodiment of the present invention, faster access
to the transmission channel is made possible. By dividing the downlink signaling
data phase into signaling data phases related to the central station and related
to the protocol, these two signaling data phases can be flexibly positioned at
different points of the transmission frame. This allows the available transmission
capacity to be fully utilized, in particular in the case where the DL-PDUs (Downlink
Protocol Data Units) are composed of elements having different lengths. If the
position of the BCH were constant, it might not be possible to fill the entire
period between the start of the transmission frame and the protocol-related signaling
data phase with useful data due to the flexible duration of the DL-PDUs. This would
result in loss of transmission capacity.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a communication network having a central station and subscribers
connected through a common medium.
FIG. 2 shows the basic structure of a transmission frame according to an example
embodiment of the present invention.
FIG. 3 shows an example of a transmission frame according to the present invention.
FIG. 4 shows a transmission frame having identifiers before the protocol-related
and the central station-related signaling data phases.
FIG. 5 shows a transmission frame having a direct identifier only before the
protocol-related signaling data phase.
FIG. 6 shows a transmission frame having an identifier immediately before the
signaling data phase related to the central station.
DETAILED DESCRIPTION
FIG. 1 shows a communication network for a communication system. A central station
1 communicates via a common transmission medium
11 having subscribers
21,
22,
23, etc. in the form of terminals, central station
1 being responsible for the coordinating function for media access (Medium
Access Control, MAC) to the jointly utilized medium. Central station
1 may
be connected to a higher-level network, so that terminals can connect to one another
and to other subscribers in the network. It is, however, also possible that the
central station
1 is not connected to a network, so that the terminals can
only communicate with central station
1 and with one another. In this case,
the traffic always goes through central station
1 or the direct exchange
between terminals must be coordinated by central station
1. A jointly utilized
transmission medium
11 is a wireless channel, for example, but can also
be a PON (Passive Optical Network) or an HFC (Hybrid Fiber Coax) network.
FIG. 2 shows the structure of a transmission frame for the communication network
illustrated in FIG. 1. Transmission frames
3 are labeled here as MAC frames,
contrary to German Patent Application No. 197 26 120 or A. Krämling et al.
"Performance Evaluation of MAC Schemes for Wireless ATM Systems with Centralised
Control Considering Processing Delays" EPMCC, Bonn, 1997, where they are labeled
as signaling periods. At the beginning of a transmission frame
3, downlink
signaling data phase
42—BCH (Broadcast Channel)—appears. It
is followed by useful signal data phase
41 for the downlink. It is labeled
as DLCH (Downlink Channel) and includes N useful data time slots for the DL-PDUs
(Downlink Protocol Data Units). Similarly, M useful data time slots are provided
for the UL-PDUs (Uplink Protocol Data Units) for useful signal data phase
51
of the uplink ULCH (Uplink Channel). Uplink signaling data phase
52 is labeled
as RACH (Random Access Channel).
Download signaling data phase BCH is divided into two categories as shown
in FIG. 2: a signaling data phase
421 related to the central station—BCCH
(Broadcast Control Channel)—and a protocol-related signaling data phase
422—FCCH
(Frame Control Channel). In BCCH
421, central station
1 can forward
information to the terminals that is of global relevance for central station
1
and the communication with the connected terminals. This includes information such
as capabilities of the central station, manufacturer information, current operating
modes, and address of the central station. On the other hand, FCCH
422 determines
the structure and the contents of the remaining transmission frame
3 (MAC
frame). Thus, FCCH has primarily local, MAC frame-related importance. In FIG. 2,
which only shows the principle of the frame structure, BCCH and FCCH are shown
directly following one another without taking into consideration the frame structure
according to the present invention which is explained below.
Initially we shall assume that the position of the BCCH which contains
the global information is always located at the beginning of MAC frame
3.
In this case, it is advantageous if the position of FCCH
422 is announced
in BCCH
421. Furthermore, it can be advantageous if a special identifier
is transmitted immediately before the occurrence of FCCH
422 in addition
to the identifier at the beginning of MAC frame
3 (see, German Patent Application
No. 197 26 120 and Karsten Brüninghaus, Markus Radimirsch, "Coarse Frame Synchronisation
for OFDM-Based Wireless Communication Systems," PIMRC, Boston, 1998). It is advantageous
if this identifier is different from the identifier at the beginning of MAC frame
3; however, in principle, it may also be identical to it.
An exemplary MAC frame
3 for a device according to the present invention
is illustrated in FIG. 3. MAC frame
3 begins with an identifier
6,
which unambiguously indicates that this is the beginning of the MAC frame. An example
of such an identifier is described, for example, in German Patent Application No.
197 26 120. It is followed by signaling data phase
421—BCCH—which
contains, among other things, the time interval (indirect identifier) between BCCH
and FCCH-T index (BCCH-FCCH). This information is evaluated by terminals
21,
22,
23, etc., so that FCCH can be demodulated in a controlled manner
as needed.
For this purpose, reference points in time are established; these are the end
of the BCCH and the beginning of the FCCH in the example according to FIG. 3. The
time reference of the BCCH may also be located at the beginning or at a point in
time in the middle of the BCCH or it may be the identifier itself. The reference
point in time of the FCCH could also be at the beginning or at some point in the
middle of the FCCH. A terminal may also receive this time interval T index (BCCH-FCCH)
as a fixed value from the manufacturer. This interval can also be determined on
the basis of manufacturer-specific considerations or from a standard.
Another option is a flexible interval T index (BCCH-FCCH), which is calculated
by central station
1 as a function of the requirements of each situation
and communicated to the terminals. The current interval can be transmitted to the
terminals in the BCCH. This allows the entire DLCH
41 (Downlink Useful Data
Signal Phase
41) to be filled if the length of the DL-PDUs is not constant,
as explained previously, but is composed of elements having different durations.
The granularity of this time interval can be measured in system cycles; in general,
the system clock is specified in a standard. Another option is the explicit specification
of a time granularity which may be the duration of the smallest unit from which
a DL-PDU can be composed, for example. This time granularity is a common divisor
of the durations of all possible DL-PDUs. The function of the FCCH is described
in detail in German Patent Application No. 197 26 120 and A. Krämling et al.
"Performance Evaluation of MAC Schemes for Wireless ATM Systems with Centralised
Control Considering Processing Delays" EPMCC, Bonn, 1997; it assigns time slots
to the terminals for reception and transmission. Both the chronological sequence
of the individual elements of a MAC frame
3 and the effects of the FCCH
are specified there. A terminal that wishes to log onto the network can calculate
the position in time of the remaining elements of MAC frame
3 and, of course,
also of the RACH from the information of the FCCH and, using this information,
begin communicating with the central station.
Additional possible embodiments of the present invention are presented below:
BCCH
421 is not located directly at the beginning of MAC frame
3,
but has a constant distance from the beginning of the MAC frame.
It is also possible to identify the position of FCCH
422 through an additional
identifier. In this case, the following combinations are possible:
an additional identifier
62 is transmitted before FCCH
422; this
identifier can be advantageously distinguished in the receiver from identifier
61 located before BCCH
421. It is also possible that FCCH
422
is announced in BCCH
421 or that BCCH
421 announces the position
of FCCH
422. This is illustrated in FIG. 4.
no identifier is inserted before BCCH
421, so the identifier
62
before FCCH
422 is unique and it unambiguously identifies the position of
FCCH
422. Also in this case, FCCH
422 may or may not be announced
in BCCH
421. This is illustrated in FIG. 5.
If the position of BCCH
421 is not located at the beginning of MAC frame
3, which is provided with identifier
6 as a frame identifier, it
may be advantageous to transmit an easy-to-detect additional identifier
61
immediately before BCCH
421. This is illustrated in FIG. 6. Here too, an
additional identifier may be inserted before FCCH
422; identifier
61
may be present before BCCH
421 or it may be omitted.
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