CA2035489C - Signalling interference protection - Google Patents
Signalling interference protectionInfo
- Publication number
- CA2035489C CA2035489C CA002035489A CA2035489A CA2035489C CA 2035489 C CA2035489 C CA 2035489C CA 002035489 A CA002035489 A CA 002035489A CA 2035489 A CA2035489 A CA 2035489A CA 2035489 C CA2035489 C CA 2035489C
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- voice channel
- odd
- channel
- adjacent
- voice
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Radar Systems Or Details Thereof (AREA)
- Time-Division Multiplex Systems (AREA)
Abstract
There is provided a mechanism for signalling interference protection comprising: transmitting, along with adjacent channel frequencies, an odd/even bit associated with odd/even channels that differentiates adjacent channel frequencies from one another, receiving transmitted an odd/even bit associated with odd/even channels that differentiates adjacent channel frequencies from one another, and responding to ~(s) of interest while remaining unresponsive to other than that of ~ St.
Description
2~~~~~~
SIGNALLING INTERFERENCE PROTECTION
This invention is concerned with signalling interterence protection.
More particularly, this invention is concerned with signalling interference protection in a (cellular radiotelephone) channel reuse network.
BACKGROUND OF THE INVENTION
In systems employing channel reuse schemes, it is a common problem to determine whether one is using the channel intended or an unintended reuse of that channel. In cellular radiotelephone systems exhibiting geographical frequency reuse, the problem is worse because cellular radiotelephones are not fully capable of rejecting not only the same frequency reused at the geographic separation distance, but also insufficiently capable of rejecting adjacent frequencies within the reuse perimeter.
US Patent No. 4,128,740 to Graziano, assigned in the instant assignee, is useful to demonstrate the point. Figure 4 of Graziano (substantially reproduced here as Figure 1 ) illustrates a conventional cellular frequency reuse plan common known as the seven-cell repeat pattern. It consists of a central cell (1 ) ringed in a clockwise direction beginning at
SIGNALLING INTERFERENCE PROTECTION
This invention is concerned with signalling interterence protection.
More particularly, this invention is concerned with signalling interference protection in a (cellular radiotelephone) channel reuse network.
BACKGROUND OF THE INVENTION
In systems employing channel reuse schemes, it is a common problem to determine whether one is using the channel intended or an unintended reuse of that channel. In cellular radiotelephone systems exhibiting geographical frequency reuse, the problem is worse because cellular radiotelephones are not fully capable of rejecting not only the same frequency reused at the geographic separation distance, but also insufficiently capable of rejecting adjacent frequencies within the reuse perimeter.
US Patent No. 4,128,740 to Graziano, assigned in the instant assignee, is useful to demonstrate the point. Figure 4 of Graziano (substantially reproduced here as Figure 1 ) illustrates a conventional cellular frequency reuse plan common known as the seven-cell repeat pattern. It consists of a central cell (1 ) ringed in a clockwise direction beginning at
3-o'clock by six ring cells (2-7), completing a seven-cell pattern. That seven-cell pattern is then itself surrounded by six other identical seven-cell patterns. Thus, the frequencies operating in each cell are geographically reused at a geographical reuse separation distance. It is W. ~~~~~~g~
this geographical frequency reuse that provides the (frequency) channel capacity to allow a large number of radiotelephone users to share a limited amount of (frequency) spectnrm. However, the neat geographical reuse separation illustrated is not quite so neat when local propagation conditions such as antenna height, buildings and obstructions) etc.) are taken into account. Accordingly) additional protection is provided against co-channel (same frequency) interference in the signalling by allocating seven differentiating codes to each of the surrounding patterns. This signalling provides some protection in that a radiotelephone is able to differentiate the frequency on which he is speaking from an interferer of the same frequency at the reuse separation distance but having a different code. In conventional analog cellular systems, these codes are Supervisory Audio Tones (SAT) and in proposed narrower band, split-channel systems, known as Digital SAT or DSAT.
The problem solved by the instant invention is that there is insufficient rejection in radiotelephones to fully reject adjacent channels just one frequency above or below the one of interest.
In his patent (US 4,128,740), Graziano teaches that greater frequency reuse (and therefore spectrum utilization) can be obtained with narrow beam, sectored antennas. The resulting four-cell pattern is still surrounded by six reuses of that same four cell pattern, advantageously employing seven DSATs for improved signalling protection against co-channel interterence. Figure 9 of Graziano (substantially reproduced here as Figure 2) illustrates a frequency plan for his "four-cell" pattern. It illustrates how 208 frequency channels are divided among 4 cells) each having 6 sectors, for a total of 24 sectors (CS1-CS24). Thus, each sector has one supervisory frequency (S1-S24) and either 7 or 8 voice frequency channels, allowing that many simultaneous conversations in each sector. The problem is that, although any given frequency being used in Sector 3 of a first pattern can be differentiated from that same co-channel frequency in Sector 3 of the pattern behind it by its DSAT, there is no protection for a radiotelephone user in Sector 3 using frequency 196 from the next higher adjacent frequency 197 directly behind it in .. IUN - 6 1994 Sector 4, or from the next lower adjacent frequency 195 in Sector 2 behind and to the side of it.
This invention takes as its object to overcome these shortcomings and to realize certain advantages presented below.
SUMMARY OF THE INVENTION
There is provided a method of signalling interference protection comprising: transmitting, in a desired channel and an interfering channel each within a reuse pattern, signalling information that differentiates the desired channel and the interfering channel from one another, receiving that transmitted differentiating information, and responding to the desired channel while remaining unresponsive to the interfering channel based on the differentiating information.
In addition, there is provided an apparatus for signalling interference protection in a channel reuse radio network, comprising, operatively coupled in series: means, in a desired channel or an interfering channel within a reuse pattern, for transmitting signalling information that differentiates the desired channel from interfering channels within the reuse pattern, means for receiving that transmitted differentiating information, and means for responding to the desired channel while remaining unresponsive to the interfering channel based on the differentiating information.
DESCRIPTION OF THE DRAWINGS
Additional objects, features and advantages of the invention will be more clearly understood and the best mode contemplated for practicing it in its preferred embodiment will be appreciated (by way of unrestricted example) from the following detailed description, taken together with the accompanying drawings in which:
_ UUN-6199 2~35~t89 - 3(a) -Figure 1 is a cellular geographical reuse diagram which is a substantial reproduction of Figure 4 of US Patent No. 4,128,740 to Graziano, assigned in the instant assignee.
Figure 2 is a cellular frequency reuse plan which is a substantial reproduction of Figure 9 of US Patent No. 4,128,740 to Graziano, assigned in the instant assignee.
~0 35 ~ ss Figure 3 is a cellular geographical reuse diagram and cellular frequency reuse plan of the network in which the invention operates in accordance with the preferred embodiment.
Figure 3 is a cellular geographical reuse diagram and cellular frequency reuse plan of the network in which the invention operates in accordance with the preferred embodiment.
Once again) the problem illustrated in Figure 3 is that, although any given frequency being used in Sector 3 of a first pattern of a mobile radiotelephone subscriber can be differentiated from that same co-channel frequency in Sector 3 of the pattern behind it by its DSAT, there is no protection for a radiotelephone user in Sector 3 using frequency 196 from the next higher adjacent frequency 197 directly behind it in Sector 4, or from the next lower adjacent frequency 195 in Sector 2 behind and to the side of it: Present systems simply do not provide protection against the most likely source of interference) an adjacent channel within its own pattern.
The instant invention provides a solution to the problem by utilizing the signalling to provide additional interference protection, not from co-channel (same frequency) interferences at the geographic reuse separation distance but from adjacent channels within the same pattern. It provides that radiotelephone receivers (and base cell site equipment) reject adjacent interferers on the basis of evenness and oddness of the frequency. For example) if a mobile radiotelephone subscriber in Sector 3 is assigned nominal channel frequency 196 (actual frequency abc.xyz MHz) - an "even" channel, his receiver would reject adjacent channel frequency 197 (actually some 12.5, 15) 25 or 30 KHz higher) in Sector 4 directly behind and channel frequency 195 (actually some 12.5, 15, 25 or 30 KHz below) in Sector 2 behind and to the side, based upon their "oddness". This substantially reduces the possibility of a receiver improperly acting upon a transmission intended for another on an adjacent channel.
If "evenness" and "oddness" were not otherwise determinable (and inherently associated with each carrier), a bit could be transmitted along with each carrier frequency to indicate "evenness" and "oddness" as by either setting or clearing that bit field. Similarly) if additional protection from interferers were desired) a one-of-n state binary word could be included in the signalling protocol for each of n partitions of the frequency spectrum. However, the usual distance 5 BCH code provides sufficient assurance that the single bit will be recoverable.
The attendant advantage of this invention clearly includes signalling protection against adjacent channel interferers within the pattern in addition to the usual SAT co-channel interference protection from outside the pattern.
Thus, there has been provided a mechanism for signalling interterence protection comprising: transmitting) along with adjacent channel frequencies, an odd/even bit associated with odd/even channels that differentiates adjacent channel frequencies from one another, receiving transmitted an odd/even bit associated with odd/even channels that differentiates adjacent channel frequencies from one another, and responding to ones) of interest while remaining unresponsive to other than that of interest.
It will be appreciated by those ordinarily skilled in the art that the means for carrying out the invention are readily available and their operation well understood. While the preferred embodiment of the invention has been described and shown, it will be appreciated by those skilled in this field that other variations and modifications of this invention may be implemented. For example) "evenness" and "oddness" could be determined from frequencies discrimination (channel spacing) or made inherent to the channels through slight variations in the bit rates used on "odd" versus "even" channels. Although the foregoing discussion has included a discussion in terms of channel frequencies, the technique is 2~~~ ~$~9 equally applicable to other channel structures such as, time slot channels or code division channels and the like.
These and all other variations and adaptations are expected to fall within the ambit of the appended claims.
this geographical frequency reuse that provides the (frequency) channel capacity to allow a large number of radiotelephone users to share a limited amount of (frequency) spectnrm. However, the neat geographical reuse separation illustrated is not quite so neat when local propagation conditions such as antenna height, buildings and obstructions) etc.) are taken into account. Accordingly) additional protection is provided against co-channel (same frequency) interference in the signalling by allocating seven differentiating codes to each of the surrounding patterns. This signalling provides some protection in that a radiotelephone is able to differentiate the frequency on which he is speaking from an interferer of the same frequency at the reuse separation distance but having a different code. In conventional analog cellular systems, these codes are Supervisory Audio Tones (SAT) and in proposed narrower band, split-channel systems, known as Digital SAT or DSAT.
The problem solved by the instant invention is that there is insufficient rejection in radiotelephones to fully reject adjacent channels just one frequency above or below the one of interest.
In his patent (US 4,128,740), Graziano teaches that greater frequency reuse (and therefore spectrum utilization) can be obtained with narrow beam, sectored antennas. The resulting four-cell pattern is still surrounded by six reuses of that same four cell pattern, advantageously employing seven DSATs for improved signalling protection against co-channel interterence. Figure 9 of Graziano (substantially reproduced here as Figure 2) illustrates a frequency plan for his "four-cell" pattern. It illustrates how 208 frequency channels are divided among 4 cells) each having 6 sectors, for a total of 24 sectors (CS1-CS24). Thus, each sector has one supervisory frequency (S1-S24) and either 7 or 8 voice frequency channels, allowing that many simultaneous conversations in each sector. The problem is that, although any given frequency being used in Sector 3 of a first pattern can be differentiated from that same co-channel frequency in Sector 3 of the pattern behind it by its DSAT, there is no protection for a radiotelephone user in Sector 3 using frequency 196 from the next higher adjacent frequency 197 directly behind it in .. IUN - 6 1994 Sector 4, or from the next lower adjacent frequency 195 in Sector 2 behind and to the side of it.
This invention takes as its object to overcome these shortcomings and to realize certain advantages presented below.
SUMMARY OF THE INVENTION
There is provided a method of signalling interference protection comprising: transmitting, in a desired channel and an interfering channel each within a reuse pattern, signalling information that differentiates the desired channel and the interfering channel from one another, receiving that transmitted differentiating information, and responding to the desired channel while remaining unresponsive to the interfering channel based on the differentiating information.
In addition, there is provided an apparatus for signalling interference protection in a channel reuse radio network, comprising, operatively coupled in series: means, in a desired channel or an interfering channel within a reuse pattern, for transmitting signalling information that differentiates the desired channel from interfering channels within the reuse pattern, means for receiving that transmitted differentiating information, and means for responding to the desired channel while remaining unresponsive to the interfering channel based on the differentiating information.
DESCRIPTION OF THE DRAWINGS
Additional objects, features and advantages of the invention will be more clearly understood and the best mode contemplated for practicing it in its preferred embodiment will be appreciated (by way of unrestricted example) from the following detailed description, taken together with the accompanying drawings in which:
_ UUN-6199 2~35~t89 - 3(a) -Figure 1 is a cellular geographical reuse diagram which is a substantial reproduction of Figure 4 of US Patent No. 4,128,740 to Graziano, assigned in the instant assignee.
Figure 2 is a cellular frequency reuse plan which is a substantial reproduction of Figure 9 of US Patent No. 4,128,740 to Graziano, assigned in the instant assignee.
~0 35 ~ ss Figure 3 is a cellular geographical reuse diagram and cellular frequency reuse plan of the network in which the invention operates in accordance with the preferred embodiment.
Figure 3 is a cellular geographical reuse diagram and cellular frequency reuse plan of the network in which the invention operates in accordance with the preferred embodiment.
Once again) the problem illustrated in Figure 3 is that, although any given frequency being used in Sector 3 of a first pattern of a mobile radiotelephone subscriber can be differentiated from that same co-channel frequency in Sector 3 of the pattern behind it by its DSAT, there is no protection for a radiotelephone user in Sector 3 using frequency 196 from the next higher adjacent frequency 197 directly behind it in Sector 4, or from the next lower adjacent frequency 195 in Sector 2 behind and to the side of it: Present systems simply do not provide protection against the most likely source of interference) an adjacent channel within its own pattern.
The instant invention provides a solution to the problem by utilizing the signalling to provide additional interference protection, not from co-channel (same frequency) interferences at the geographic reuse separation distance but from adjacent channels within the same pattern. It provides that radiotelephone receivers (and base cell site equipment) reject adjacent interferers on the basis of evenness and oddness of the frequency. For example) if a mobile radiotelephone subscriber in Sector 3 is assigned nominal channel frequency 196 (actual frequency abc.xyz MHz) - an "even" channel, his receiver would reject adjacent channel frequency 197 (actually some 12.5, 15) 25 or 30 KHz higher) in Sector 4 directly behind and channel frequency 195 (actually some 12.5, 15, 25 or 30 KHz below) in Sector 2 behind and to the side, based upon their "oddness". This substantially reduces the possibility of a receiver improperly acting upon a transmission intended for another on an adjacent channel.
If "evenness" and "oddness" were not otherwise determinable (and inherently associated with each carrier), a bit could be transmitted along with each carrier frequency to indicate "evenness" and "oddness" as by either setting or clearing that bit field. Similarly) if additional protection from interferers were desired) a one-of-n state binary word could be included in the signalling protocol for each of n partitions of the frequency spectrum. However, the usual distance 5 BCH code provides sufficient assurance that the single bit will be recoverable.
The attendant advantage of this invention clearly includes signalling protection against adjacent channel interferers within the pattern in addition to the usual SAT co-channel interference protection from outside the pattern.
Thus, there has been provided a mechanism for signalling interterence protection comprising: transmitting) along with adjacent channel frequencies, an odd/even bit associated with odd/even channels that differentiates adjacent channel frequencies from one another, receiving transmitted an odd/even bit associated with odd/even channels that differentiates adjacent channel frequencies from one another, and responding to ones) of interest while remaining unresponsive to other than that of interest.
It will be appreciated by those ordinarily skilled in the art that the means for carrying out the invention are readily available and their operation well understood. While the preferred embodiment of the invention has been described and shown, it will be appreciated by those skilled in this field that other variations and modifications of this invention may be implemented. For example) "evenness" and "oddness" could be determined from frequencies discrimination (channel spacing) or made inherent to the channels through slight variations in the bit rates used on "odd" versus "even" channels. Although the foregoing discussion has included a discussion in terms of channel frequencies, the technique is 2~~~ ~$~9 equally applicable to other channel structures such as, time slot channels or code division channels and the like.
These and all other variations and adaptations are expected to fall within the ambit of the appended claims.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a channel reuse radio network, a method of signalling interference protection, the method comprising the steps of:
transmitting signalling information in a desired voice channel and an interfering voice channel which is adjacent to the desired voice channel, each voice channel being utilized within a reuse pattern, the signalling information differentiating the desired voice channel and the interfering voice channel from one another, receiving that transmitted differentiating information, and responding only to the desired voice channel based on the differentiating information.
transmitting signalling information in a desired voice channel and an interfering voice channel which is adjacent to the desired voice channel, each voice channel being utilized within a reuse pattern, the signalling information differentiating the desired voice channel and the interfering voice channel from one another, receiving that transmitted differentiating information, and responding only to the desired voice channel based on the differentiating information.
2. In a channel reuse radio network, a method of signalling interference protection, the method comprising the steps of:
receiving information transmitted in a desired voice channel and in an interfering voice channel which is adjacent to the desired voice channel, the transmitted information differentiating the desired voice channel from the interfering voice channel, each voice channel utilized within a reuse pattern, and responding only to transmissions of the desired voice channel based on the differentiating information.
receiving information transmitted in a desired voice channel and in an interfering voice channel which is adjacent to the desired voice channel, the transmitted information differentiating the desired voice channel from the interfering voice channel, each voice channel utilized within a reuse pattern, and responding only to transmissions of the desired voice channel based on the differentiating information.
3. In a channel reuse radio network, a method of signalling interference protection, the method comprising the steps of:
providing information in a desired voice channel and an interfering voice channel which is adjacent to the desired voice channel, the information differentiating the interfering voice channel from the desired voice channel, and transmitting, within a reuse pattern and in at least the interfering voice channel, the information differentiating the interfering voice channel from the desired voice channel.
providing information in a desired voice channel and an interfering voice channel which is adjacent to the desired voice channel, the information differentiating the interfering voice channel from the desired voice channel, and transmitting, within a reuse pattern and in at least the interfering voice channel, the information differentiating the interfering voice channel from the desired voice channel.
4. In a channel reuse radio network, a method of signalling interference protection, the method comprising the steps of:
differentiating, within a reuse pattern, between a desired voice channel and an interfering voice channel which is adjacent to the desired voice channel, and responding to the desired voice channel while remaining unresponsive to the interfering voice channel based on the differentiation.
differentiating, within a reuse pattern, between a desired voice channel and an interfering voice channel which is adjacent to the desired voice channel, and responding to the desired voice channel while remaining unresponsive to the interfering voice channel based on the differentiation.
5. A method as claimed in any one of claims 1-4, wherein the interfering voice channel comprises a voice channel having a frequency adjacent to the frequency of the desired voice channel.
6. In a channel reuse radio network, a method of adjacent voice channel interference protection, the method comprising the steps of:
transmitting, in adjacent voice channels, an odd/even bit associated with odd/even voice channels that differentiates adjacent voice channels from one another, receiving the transmitted odd/even bit associated with odd/even voice channels differentiating adjacent voice channels from one another, and responding only to a desired one of the adjacent voice channels based on the odd/even bit associated with the desired adjacent voice channel.
transmitting, in adjacent voice channels, an odd/even bit associated with odd/even voice channels that differentiates adjacent voice channels from one another, receiving the transmitted odd/even bit associated with odd/even voice channels differentiating adjacent voice channels from one another, and responding only to a desired one of the adjacent voice channels based on the odd/even bit associated with the desired adjacent voice channel.
7. In a channel reuse radio network, a method of adjacent voice channel interference protection, the method comprising the steps of:
transmitting, in voice channels having adjacent frequencies, an odd/even bit associated with odd/even frequencies that differentiates adjacent voice channel frequencies from one another, receiving the transmitted odd/even bit associated with odd/even frequencies differentiating adjacent voice channel frequencies from one another, and responding only to a voice channel as a desired frequency based on the odd/even bit associated with the voice channel at the desired frequency.
transmitting, in voice channels having adjacent frequencies, an odd/even bit associated with odd/even frequencies that differentiates adjacent voice channel frequencies from one another, receiving the transmitted odd/even bit associated with odd/even frequencies differentiating adjacent voice channel frequencies from one another, and responding only to a voice channel as a desired frequency based on the odd/even bit associated with the voice channel at the desired frequency.
8. An apparatus for providing adjacent voice channel interference protection in a channel reuse radio network, comprising, operatively coupled in series:
means for transmitting, in adjacent voice channels, an odd/even bit associated with odd/even voice channel that differentiates adjacent voice channels from one another, means for receiving the transmitted odd/even bit associated with odd/even voice channels differentiating adjacent voice channels from one another, and means for responding only to a desired one of the adjacent voice channels based on the odd/even bit associated with the desired adjacent voice channel.
means for transmitting, in adjacent voice channels, an odd/even bit associated with odd/even voice channel that differentiates adjacent voice channels from one another, means for receiving the transmitted odd/even bit associated with odd/even voice channels differentiating adjacent voice channels from one another, and means for responding only to a desired one of the adjacent voice channels based on the odd/even bit associated with the desired adjacent voice channel.
9. An apparatus for providing adjacent voice channel interference protection in a channel reuse radio network, comprising, operatively coupled in series:
means for transmitting, in voice channels having adjacent frequencies, an odd/even bit associated with odd/even frequencies that differentiates adjacent voice channel frequencies from one another, means for receiving the transmitted odd/even bit associated with odd/even frequencies differentiating adjacent voice channel frequencies from one another, and means for responding only to a voice channel as a desired frequency based on the add/even bit associated with the voice channel at the desired frequency.
means for transmitting, in voice channels having adjacent frequencies, an odd/even bit associated with odd/even frequencies that differentiates adjacent voice channel frequencies from one another, means for receiving the transmitted odd/even bit associated with odd/even frequencies differentiating adjacent voice channel frequencies from one another, and means for responding only to a voice channel as a desired frequency based on the add/even bit associated with the voice channel at the desired frequency.
10. In a channel reuse radio network, a method of signalling interference protection, the method comprising the steps of:
transmitting, in odd/even voice channels which are adjacent to each other, an odd/even bit associated with the odd/even voice channels that differentiates the odd voice channel and the adjacent even voice channel from one another, receiving the transmitted odd/even bit associated with the odd/even voice channels differentiating the odd and even voice channels from one another, and responding to a desired one of the odd or even voice channels based on reception of the odd/even bit associated therewith.
transmitting, in odd/even voice channels which are adjacent to each other, an odd/even bit associated with the odd/even voice channels that differentiates the odd voice channel and the adjacent even voice channel from one another, receiving the transmitted odd/even bit associated with the odd/even voice channels differentiating the odd and even voice channels from one another, and responding to a desired one of the odd or even voice channels based on reception of the odd/even bit associated therewith.
11. The method of claim 10 wherein the step of responding further comprises the steps of responding to an odd voice channel upon reception of an odd bit and rejecting adjacent even voice channels based on their associated even bits, and vice versa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002035489A CA2035489C (en) | 1991-02-01 | 1991-02-01 | Signalling interference protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002035489A CA2035489C (en) | 1991-02-01 | 1991-02-01 | Signalling interference protection |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2035489A1 CA2035489A1 (en) | 1992-08-02 |
| CA2035489C true CA2035489C (en) | 1999-09-07 |
Family
ID=4146930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002035489A Expired - Fee Related CA2035489C (en) | 1991-02-01 | 1991-02-01 | Signalling interference protection |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2035489C (en) |
-
1991
- 1991-02-01 CA CA002035489A patent/CA2035489C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2035489A1 (en) | 1992-08-02 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDC | Correction of dead application (reinstatement) | ||
| MKLA | Lapsed |