MXPA97001965A - Transmission of control messages in telephone digi - Google Patents

Abstract

In a communications network that involves the transmission of data packets, the control messages are assigned priorities depending on the type of message. Hosting the messages to the TDM / TDMA time segments depends on priority assignments

Description

TRANSMISSION OF CONTROL MESSAGES IN DIGITAL TELEPHONY The invention relates to the transmission of control messages in time segments within time frames of fixed length, in particular, in digital telephony time division multiplexing / time division multiple access (TDM / TDMA). The present invention is defined in the claims to which reference should now be made. The present invention relates to a method of transmitting control messages between nodes in a TDM / TDMA network in which control messages are assigned priorities depending on the type of message and the housing of messages for time segments TDM / TDMA depends on the assigned priorities. Each message has an assigned priority that can be designated by a value. For some messages, the associated priority value is increased for each transmitted frame in which the message is of a very low priority to be sent. The method is particularly applicable when a plurality of control messages are to be sent by means of a shared TDM / TDMA link. The different types of messages The present invention also relates to a transmitter TDM / TDMA which includes operational allocation means for assigning priorities for controlling messages and operational hosting means for assigning channels to TDM / TDMA time segments for transmission. The node or transmitter can be a base station or a subscriber unit. A preferred embodiment of the invention will now be described, by way of example, with reference to the drawings in which: Figure 1 is a schematic diagram illustrating the system including a base station (BTE-Base Terminal Equipment) and a Subscriber unit (NTE-Network Terminal Equipment); Figure 2 is a diagram illustrating the frame structure and time control for a double lace; Figure 3 is a schematic illustration of the priority assignment of the control message in normal data packets for transmission in respective time segments; and Figure 4 is a schematic illustration of the priority assignment of the control message in uplink pilot packets for transmission in respective time slots.

The Basic System As shown in Figure 1, the preferred system is part of a telephone system in which the local wired circuit since the switch to the subscriber has been replaced by a link full double radio between a fixed base station and a fixed subscriber unit. The preferred system includes the double radio link and the transmitters and receivers to implement the necessary protocol. There are similarities between the preferred system and digital cellular mobile phone systems such as GSM that are known in the art. This system uses a protocol based on a layered model, in particular, the following layers: PHY (Physical), -MAC (Medium Access Control), DLC (Data Link Control), NWK (Network). A difference compared to GSM is that, in the preferred system, the subscriber units are in fixed locations and there is no need for loose layouts or other features that relate to mobility. This means, for example, that directional antenna and main electricity can be used in the preferred system. Each base station in the preferred system provides six double radio links on twelve frequencies selected from the general frequency housing, to minimize interference between nearby base stations. The frame structure v r.nntrnl rto tipmnn nara ol ßnlarß rlnhla eo mu Descending are TDM and the uplinks are TDMA. The modulation of all the links is p / 4 - DPQ PS K and the basic structure for all the links is ten segments per 2560-bit frame. The bit rate is 512 kbps. Downlinks are continuously transmitted and incorporate a transmission channel for essential system information. When there is no user information to be transmitted, the downlink transmissions continue to use the basic quad and segment structure and contain an adequate fill pattern. Both for downlink and uplink transmissions, there are two types of segments, normal segments that are used after call set-up, and pilot segments that are used during call set-up. Each normal downlink segment comprises 24 bits of synchronization information followed by 24 bits designated S-field including an 8-bit header, followed by 160 bits designated D-field. These are followed by 24 bits of Error Correction for Forward and an end of pulse of 8 bits, followed by 12 bits of transmission channel. The transmission channel consists of segments in each one of the elements, such as a superframe, messages without connection and other basic information for the operation of the system. The D-field may contain either I or FAS data channels and, the S-field may contain either MS or SAS channel data. I denotes information data, which in the case of normal telephone use is digital speech although other digital data may be such as fax / modulator communications and ISDN data. MS, FAS and SAS are system control messages of which MS messages tend to be for call establishment and MAC protocol control. The associated slow signaling SAS tends to be used for in-call system control and the associated signaling FAS messages are sent for fast call setup when the information data I has not yet been sent. During call set-up, each downlink pilot segment contains frequency correction data and a tracking sequence for initializing the receiver with only a short S-field and no field information. D. The link segments Ascending basically contain two different types of data packet. The first type of packet, called the pilot packet, is used before a connection is established, for example, for a call request Aloha and to allow for adaptive time alignment. The other type of data packet, called the normal packet, is used when a call has been established and is a larger data packet, due to the use of adaptive time alignment.

Each normal uplink packet contains a 244-bit data packet that is preceded and followed by a 4-bit duration ramp. The ramps and the remaining bits outside the 256-bit segment provide a guard space against interference from nearby segments due to time control errors. Each subscriber unit adjusts the time control of its segment transmission to compensate for the time the signals take to reach the base station. Each normal uplink data packet comprises 24 bits of synchronization data followed by an S-field and a D-field of the same number of bits as in each normal downlink segment. Each uplink pilot segment contains a pilot data packet that is 196 bits long preceded and followed by 4-bit ramps that define an extended 60-bit guard space. This larger guard space is necessary since there is no time control information available and without it the propagation delays would cause nearby segments to interfere. The pilot packet comprises 64 synchronization bits followed by 104 bits of the S-field that start with an 8 bit header and end with a Cyclic Redundancy Check of 16 bits, 2 reserved bits, 14 FEC bits and 8 bits of end of pulse . There is no D-field. The S-field of an uplink pilot packet may contain a short information message, known as a UC message without an uplink connection. The S-field downlink may include a short information message of a DC message without a downlink connection. In the preferred system, the subscriber unit authentication using a polling response protocol is provided. General coding is provided by the combination of speech or data with an unpredictable sequence of digit bits produced by a key current generator that is synchronized to the transmitted superframe number. In addition, the transmitted signal is mixed to remove the components.

Multiplexing Control Messages Signaling messages from two or more sources that share a common communications channel are multiplexed by assigning priorities to messages and transmitting in each frame the message that has the highest priority. Unsent messages may have selectively increased their priority each frame until they are sent. In this way the available bandwidth is shared between the different message sources in some predetermined way, although all the bandwidth is available for any source if there is no traffic from the others. This technique is used to multiplex MS signals (known as MAC Signaling) with upper layer frame data segments ie SAS messages. MS messages have a fixed priority depending on their type considering that the SAS data segments have increased their priority for each frame in which they remain unsent. If neither MAC Signaling nor a SAS data segment is available then a filling message (MS-Unoccupied) is sent.

Priority Assignment Scheme for MS and SAS Control Messages Normal packages can carry control messages Ms or SAS. The Priority Allocation Scheme is designed to ensure that the message sources are granted adequate actions of the available bandwidth. However, all bandwidth can be available for any source if there is no traffic from the others. The rules are as follows: 1. The multiplexer has 4 input rows, one for each category of the MS message (each of a length message) and one for SAS (of a length segment). 2. MS messages are given a fixed priority. 3. The SAS segments are given an initial priority value that is incremented by 2 for each carrier for which it has been delayed. 4. The multiplexer transmits on each available carrier the message with the highest priority that can be transmitted on those carriers unless 16 consecutive segments on that carrier have been transmitted. 5. If 16 consecutive SAS segments have been sent on any carrier and there is no other Ms message for sending then the MS-Unoccupied-2 message will be sent. Priorities are assigned as shown in the Table C uad ro 1 P riori da d es M S / SAS The assignment of these different message types is illustrated schematically in Figure 3.

Priority Assignment Scheme for MS v U C messages in pilot packets The uplink packets of the Uplink sent in AIoha segments can carry either MS system control messages or U C messages (called uplink without connection). The Priority Assignment Scheme is designed to ensure that the message sources have assigned appropriate actions of the available bandwidth. However, all the bandwidth can be available for any source if there is no traffic from the others. The rules are as follows: 1. The multiplexer has 2 input rows, one for MS messages and one for UC messages (each of a length message). 2. MS messages are given a fixed priority. 3. The UC segments are given an initial priority value that is increased by 2 considering that an MS message is passed to the AIoha protocol. 4. The multiplier moves to the containment protocol the message with the highest priority. The priorities are assigned as shown in table 2: C oad ro 2 P riorities MS / UC The prioritization of these different message types is illustrated in Figure 4. A subscriber unit (NTE) is able to access at least one aloha segment. Subscriber units may be able to access more than one segment aloha per frame provided that the random access rules are respected.

Priorities granted to MS v DC messages in the Transmission Channel. The downlink transmission signaling MS is multiplexed in the Transmission channel with the DC signals without downlink connection. Consequently, the Transmission channel may contain addressed messages and / or system transmission messages. For terminals that operate in light duty cycle mode any directed message must be sent in the appropriate box within the multiple frame. In the transmission channel, the MS messages are labeled as follows: A Request for Notice Request for Multiple Carrier Warning B Channel Accommodation Resource Request Recognition C can to the logic DC D Segment-List E Transmission messages of the system (Carrier-Numbered Number Chart) MS-Unoccupied-B Messages in categories A and C when used to move their scripters into Lightweight Workload operation must be sent in the multipleset corresponding to the base station warning g roup. Messages in category B can be sent in any box. Only tables 0 to 7 can be used for groups of notice to subscribers in light duty operation. A subscriber in warning group M needs to attend only the M box of each multiple frame for messages in categories A and C. The priority of transmission MS messages and data on the DC channel are shown in Table 3.

Table 3: Transmission Priority Table Notes: 1. Since there are 10 octets in length, the Ch-Alloc message and Multiple Carrier Warning Request and the DC logical channel messages may appear only as Message 1 and in the boxes where they are used there will be no message 2. 2. Since there are 1 0 octets in length, the Ch-Alloc message and the Multiple Carrier Warning Request and the can messages to the DC logic may not appear in tables 8, 9, 12 or 13 to guarantee the contents of a second message 3. It is guaranteed that the segment list appears in at least tables 8, 9, 12 and 13. 4. It is guaranteed that the system transmission information appears in at least table 15. The message MS-Unemployed-B Use only when another message is not available. The messages in priorities A, B, and D are addressed to the subscribing units. The Warning Request and control messages when used to direct subscriber units in the light duty cycle mode must be sent in the correct box in the multiple box. The channel housing (Ch-Alloc) can be sent in any box. Except for segment-list messages, when two MS messages are sent in a frame the second message does not repeat the first one, for example, a transmission data unit may contain two Warning Request messages, but only if they are rigid. to different subscriber units. The MS messages are five binary octets except the Multiple Carrier Alert Request and Ch Alloc messages that are 10 octets in length. DC messages are also 1 0 octets. Only frames 0 to 7 of the multiple frame can be used for warning groups of the subscribing units that are in a reduced duty cycle operation. The reduced duty cycle operation allows a unit to remain in a ready state to receive a call while conserving power.

Claims (21)

1. CLAIMS 1 . A method of transmitting control messages in time segments within time frames of fixed length in which control messages are assigned priorities depending on the type of control message in accordance with a rule where each set of The control message types have a corresponding predetermined priority and, the control messages are housed into time segments depending on their assigned priority.
2. 2. A method of transmitting control messages according to claim 1, wherein each message has a priority assigned by a value.
3. 3. A control message transmission method according to claim 2, wherein for the selected message type (s), the assigned priority values are incremented for each frame in which another priority message was sent highest.
4. 4. A method of transmitting control messages according to any preceding claim, wherein the data constituting a control message is housed in predetermined portions of at least one time segment.
5. 5. A method of transmitting control messages according to any preceding claim, wherein the control messages are transmitted from a subscribing unit to a base unit.
6. A method of transmitting control messages according to claim 5, wherein for the transmission in time segments after the adaptive time alignment of the transmissions between the subscriber unit and the base station is given a priority The default setting to a call set-up control (MS) message and a locked control message (SAS) is given an increased priority for each frame for which the call control message (SAS) is not sent.
7. 7. A method according to claim 6, wherein the MS messages include the related bearer messages, the related connection messages and the Access Medium Control (MAC) messages.
8. 8. A method according to claim 7, wherein to a carrier-related message is assigned a priority value of 6, an Access Medium Control message is given a priority value of four already In-call control messages were given an initial priority value of 1.
9. 9. A method according to any of claims 6 to 8, wherein the priority value of in-call control messages (SAS) is increased by 2 in each quad.
10. A method of transmitting control messages according to claim 5, wherein for the transmission in time segments before the adaptive time alignment of the transmission between the subscriber unit and the base station, the messages of control include a call set-up control (MS) message and data messages (UC). eleven .
11. A method of transmitting control messages according to any preceding claim, wherein the frames are grouped in a repeating sequence (multiple frame) of frame groupings, the messages having priorities that depend on which current frame group they are on. .
12. 12. A method according to claim 1, wherein the control messages are sent from the base station to the subscriber unit, a selected message type being sent only in selected frame groupings. 3.
13. A method according to claim 12, in which the warning messages are sent only in frame groupings for which the subscriber units are waiting for a possible warning message.
14. 14. A method according to claim 13, wherein the warning messages are sent in any of frames 0 to 7 of a sixteen frame repetition sequence.
15. 15. A method according to claim 13 or claim 14, wherein the warning messages are expected only by a subscriber unit in a reduced duty cycle mode.
16. 16. A method of transmitting control messages according to any of claims 1 to 15, wherein the aloha segment messages are transmitted only in frame groupings of the repeated sequence.
17. 17. A method of transmitting control messages according to any preceding claim, wherein the transmissions are by radio.
18. 18. A transmitter for transmitting data packets in time segments within fixed-length time frames including operational allocation means for assigning priorities to the control messages in accordance with a rule whereby each set of message types of The control has a predetermined corresponding priority depending on the type of control message and operative hosting means for assigning the messages to time segments for transmission depending on their assigned priorities.
19. 19. A transmitter according to claim 18, comprising a base station that transmits data pa- pers in multiple format by time division and receives data packets in time division multiple access format.
20. 20. A transmitter according to claim 18, comprising a subscriber unit in a fixed location that transmits data packets in time division multiple access format and receives data packets in the latest format by time division. . twenty-one . A method of transmitting digital messages in time segments within time frames of fixed length, in which control messages are assigned priorities depending on the type of control message in accordance with a rule by which each set of Control message types have a corresponding predetermined priority dependent on the type of control message and control messages are housed in time segments for transmission depending on their assigned priorities.