U.S. patent application number 12/212387 was filed with the patent office on 2009-01-15 for received signal quality determination.
This patent application is currently assigned to Spyder Navigations L.L.C.. Invention is credited to Tommy Kristensen Bysted, Benoist Sebire.
Application Number | 20090016473 12/212387 |
Document ID | / |
Family ID | 35096188 |
Filed Date | 2009-01-15 |
United States Patent
Application |
20090016473 |
Kind Code |
A1 |
Bysted; Tommy Kristensen ;
et al. |
January 15, 2009 |
RECEIVED SIGNAL QUALITY DETERMINATION
Abstract
A method of generating a received signal quality signal in a
communication system, the method comprising: receiving a signal
from a physical channel, extracting a transport channel format
combination indicator from the received signal, processing one or
more transport channel signals, contained in the received signal,
in accordance with the extracted transport channel format
combination indicator, said processing including at least channel
decoding, and generating a received signal quality signal in
dependence on the quality of the or each transport channel signal
prior to channel decoding.
Inventors: |
Bysted; Tommy Kristensen;
(Smoerum, DK) ; Sebire; Benoist; (Beijing,
CN) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
1875 EYE STREET, N.W., SUITE 1100
WASHINGTON
DC
20006
US
|
Assignee: |
Spyder Navigations L.L.C.
Wilmington
DE
|
Family ID: |
35096188 |
Appl. No.: |
12/212387 |
Filed: |
September 17, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10825401 |
Apr 15, 2004 |
7437174 |
|
|
12212387 |
|
|
|
|
Current U.S.
Class: |
375/346 |
Current CPC
Class: |
H04L 1/203 20130101;
H04B 17/309 20150115 |
Class at
Publication: |
375/346 |
International
Class: |
H04B 1/10 20060101
H04B001/10 |
Claims
1.-20. (canceled)
21. A method of generating a received signal quality signal in a
communication system, the method comprising: receiving a signal
from a physical channel, the signal comprising a plurality of
bursts each including a training sequence; and generating a
received signal quality signal in dependence on the bit error rate
of the training sequence of a received burst.
22. The method according to claim 21, wherein the determined bit
error rates of the training sequences of a plurality of bursts are
averaged.
23. The method according to claim 21, wherein the bit error rate of
a training sequence is produced by comparing a received training
sequence with a reference training sequence.
24. The method according to claim 21, further including
transmitting the received signal quality signal in a control
channel.
25. A communication device comprising: a receiver to receive a
signal from a physical channel, the signal comprising a plurality
of bursts, each including a training sequence; and processing means
configured to generate a received signal quality signal in
dependence on the bit error rate of the training sequence of a
received burst.
26. The device according to claim 25, wherein the processing means
is configured to average the determined bit error rates of the
training sequences of a plurality of bursts.
27. The device according to claim 25, wherein the processing means
is configured to produce the bit error rate of a training sequence
by comparing a received training sequence with a reference training
sequence.
28. The device according to claim 25, further including a
transmitter, wherein the processing means is configured to cause
the transmitter to transmit the received signal quality signal in a
control channel of a communication network.
29. A processor-readable medium containing processor-executable
instructions that, when executed by a processor, cause the
processor to implement a method of generating a received signal
quality signal in a communication system, the method comprising:
receiving a signal from a physical channel, the signal comprising a
plurality of bursts each including a training sequence; and
generating a received signal quality signal in dependence on the
bit error rate of the training sequence of a received burst.
30. The medium according to claim 29, wherein the determined bit
error rates of the training sequences of a plurality of bursts are
averaged.
31. The medium according to claim 29, wherein the bit error rate of
a training sequence is produced by comparing a received training
sequence with a reference training sequence.
32. The medium according to claim 29, wherein the method further
includes transmitting the received signal quality signal in a
control channel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the determination of
received signal quality in a radio communication system.
BACKGROUND TO THE INVENTION
[0002] In a radio communication network, such as a mobile phone
network, mobile stations monitor the quality of received signals
and report the received signal quality back to a base station,
typically in a control channel.
[0003] It has been proposed that a mobile station report received
signal quality in a slow associated control channel (SACCH) using a
three bit code. The signal quality is determined as the bit error
rate (BER) of the received signal before channel decoding and is
averaged over one SACCH multiframe, for example 480 ms.
[0004] The BER is only used if the a block is correctly received,
i.e. it passes a CRC (cyclic redundancy code) check. If a block is
not correctly received, a default notional BER of, for example 50%,
is assumed.
SUMMARY OF THE INVENTION
[0005] According to a first aspect of the present invention, there
is provided a method of generating a received signal quality signal
in a communication system, the method comprising: [0006] receiving
a signal from a physical channel; [0007] extracting a transport
channel format combination indicator from the received signal;
[0008] processing one or more transport channel signals, contained
in the received signal, in accordance with the extracted transport
channel format combination indicator; said processing including at
least channel decoding; and [0009] generating a received signal
quality signal in dependence on the quality of the or each
transport channel signal prior to channel decoding.
[0010] According to the first aspect of the present invention,
there is also provided a communication device comprising: [0011] a
receiver for receiving a signal from a physical channel; [0012]
processing means configured for: [0013] extracting a transport
channel format combination indicator from the received signal;
[0014] processing one or more transport channel signals, contained
in the received signal, in accordance with the extracted transport
channel format combination indicator; said processing including at
least channel decoding; and [0015] generating a received signal
quality signal in dependence on the quality of the or each
transport channel signal prior to channel decoding.
[0016] The or each transport channel signal may comprise a sequence
of data blocks. The quality of the or each transport channel signal
may be represented by a block bit error rate determined prior to
channel decoding. The determined bit error rate of a transport
channel signal may be averaged over period comprising a plurality
of data blocks. In the case of there being a plurality of transport
channel signals, the bit error rates of each transport channel
signal may be averaged over the same period. An average bit error
rate may be calculated across the transport channel signals with
the averaging being weighted in dependence on the transport formats
used for said transport signals.
[0017] The received signal quality signal may be transmitted in a
control channel.
[0018] According to a second aspect of the present invention, there
is provided a method of generating a received signal quality signal
in a communication system, the method comprising: [0019] receiving
a signal from a physical channel, the signal comprising one or more
transport channels; [0020] extracting a transport channel format
combination indicator from the received signal and determining the
bit error rate therefore, and [0021] generating a received signal
quality signal in dependence on the bit error rate of the extracted
transport channel format combination indicator.
[0022] According to the second aspect of the present invention,
there is also provided a communication device comprising: [0023] a
receiver for receiving a signal from a physical channel, the signal
comprising one or more transport channels; and [0024] processing
means configured for: [0025] extracting a transport channel format
combination indicator from a received signal and determining the
bit error rate therefore; and [0026] generating a received signal
quality signal in dependence on the bit error rate of the extracted
transport channel format combination indicator.
[0027] The determined bit error rates of a plurality of transport
channel format combination indicator instances may be averaged.
[0028] The received signal quality signal may be transmitted in a
control channel.
[0029] According to a third aspect of the present invention, there
is provided a method of generating a received signal quality signal
in a communication system, the method comprising: [0030] receiving
a signal from a physical channel, the signal comprising a plurality
of bursts each including a training sequence; and [0031] generating
a received signal quality signal in dependence on the bit error
rate of the training sequence of a received burst.
[0032] According to the third aspect of the present invention,
there is also provided a communication device comprising: [0033] a
receiver for receiving a signal from a physical channel, the signal
comprising a plurality of bursts each including a training
sequence; and [0034] processing means configured for generating a
received signal quality signal in dependence on the bit error rate
of the training sequence of a received burst.
[0035] The determined bit error rates of the training sequences of
a plurality of bursts may be averaged.
[0036] The bit error rate of a training sequence may be produced by
comparing a received training sequence with a reference training
sequence.
[0037] The received signal quality signal may be transmitted in a
control channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 shows a mobile communication system according to the
present invention;
[0039] FIG. 2 is a block diagram of a mobile station;
[0040] FIG. 3 is a block diagram of a base transceiver station;
[0041] FIG. 4 illustrates the frame structure;
[0042] FIG. 5 illustrates a packet data channel;
[0043] FIG. 6 illustrates the sharing of a radio channel between
two half-rate packet channels;
[0044] FIG. 7 illustrates the lower levels of a protocol stack;
[0045] FIG. 8 is a block diagram illustrating the processing of the
transport channels of a received physical layer signal;
[0046] FIG. 9 is a block diagram illustrating received signal
quality determination;
[0047] FIG. 10 is a flowchart of a first part of a received signal
quality determination process;
[0048] FIG. 11 is a flowchart of a second part of a received signal
quality determination process;
[0049] FIG. 12 is a block diagram illustrating another approach to
signal quality determination;
[0050] FIG. 13 is a flowchart illustrating another received signal
quality determination process;
[0051] FIG. 14 is a block diagram illustrating yet another approach
to signal quality determination; and
[0052] FIG. 15 is a flowchart illustrating yet another received
signal quality determination process.
DETAILED DESCRIPTION OF EMBODIMENTS
[0053] Embodiments of the present invention will now be described,
by way of example, with reference to the accompanying drawings.
[0054] Referring to FIG. 1, a mobile phone network 1 comprises a
plurality of switching centres including first and second switching
centres 2a, 2b. The first switching centre 2a is connected to a
plurality of base station controllers including first and second
base station controllers 3a, 3b. The second switching centre 2b is
similarly corrected to a plurality of base station controllers (not
shown).
[0055] The first base station controller 3a is connected to and
controls a base transceiver station 4 and a plurality of other base
transceiver stations. The second base station controller 3b is
similarly connected to and controls a plurality of base transceiver
stations (not shown).
[0056] In the present example, each base transceiver station
services a respective cell. Thus, the base transceiver station 4
services a cell 5. However, a plurality of cells may be serviced by
one base transceiver station by means of directional antennas. A
plurality or mobile stations 6a, 6b are located in the cell 5. It
will be appreciated what the number and identities of mobile
stations in any given cell will vary with time.
[0057] The mobile phone network 1 is connected to a public switched
telephone network 7 by a gateway switching centre 8.
[0058] A packet service aspect of the network includes a plurality
of packet service support nodes (one shown) 9 which are connected
to respective pluralities of base station controllers 3a, 3b. At
least one packet service support gateway node 10 connects the or
each packet service support node 10 to the Internet 11.
[0059] The switching centres 3a, 3b and the packet service support
nodes 9 have access to a home location register 12.
[0060] Communication between the mobile stations 6a, 6b and the
base transceiver station 4 employs a time-division multiple access
(TDMA) scheme.
[0061] Referring to FIG. 2, the first mobile station 6a comprises
an antenna 101, an rf subsystem 102, a baseband DSP (digital signal
processing) subsystem 103; an analogue audio subsystem 104, a
loudspeaker 105, a microphone 106, a controller 107, a liquid
crystal display 108, a keypad 109, memory 110, a battery 111 and a
power supply circuit 112.
[0062] The rf subsystem 102 contains if and rf circuits of the
mobile telephone's transmitted and receiver and a frequency
synthesizer for tuning the mobile station's transmitter and
receiver. The antenna 101 is coupled to the rf subsystem 102 for
the reception and transmission of radio waves.
[0063] The baseband DSP subsystem 103 is coupled to the rf
subsystem 102 to receive baseband signals therefrom and for sending
baseband modulation signals thereto. The baseband DSP subsystems
103 includes codec functions which are well-known in the art.
[0064] The analogue audio subsystem 104 is coupled to the baseband
DSP subsystem 103 and receives demodulated audio therefrom. The
analogue audio subsystem 104 amplifies the demodulated audio and
applies it to the loudspeaker 105. Acoustic signals, detected by
the microphone 106, are pre-amplified by the analogue audio
subsystem 104 and sent to the baseband DSP subsystem 4 for
coding.
[0065] The controller 107 controls the operation of the mobile
telephone. It is coupled to the rf subsystem 102 for supplying
tuning instructions to the frequency synthesizer and to the
baseband DSP subsystem 103 for supplying control data and
management data for transmission. The controller 107 operates
according to a program stored in the memory 110. The memory 110 is
shown separately from the controller 107. However, it may be
integrated with the controller 107.
[0066] The display device 108 is connected to the controller 107
for receiving control data and the keypad 109 is connected to the
controller 107 for supplying user input data signals thereto.
[0067] The battery 111 is connected to the power supply circuit 112
which provides regulated power at the various voltages used by the
components of the mobile telephone.
[0068] The controller 107 is programmed to control the mobile
station for speech and data communication and with application
programs, e.g. a WAP browser, which make use of the mobile
station's data communication capabilities.
[0069] The second mobile station 6b is similarly configured.
[0070] Referring to FIG. 3, greatly simplified, the base
transceiver station 4 comprises an antenna 201, an rf subsystem
202, a baseband DSP (digital signal processing) subsystem 203, a
base station controller interface 204 and a controller 207.
[0071] The rf subsystem 202 contains the if and rf circuits of the
base transceiver station's transmitter and receiver and a frequency
synthesizer for tuning the base transceiver station's transmitter
and receiver. The antenna 201 is coupled to the rf subsystem 202
for the reception and transmission of radio waves.
[0072] The baseband DSP subsystem 203 is coupled to the rf
subsystem 202 to receive baseband signals therefrom and for sending
baseband modulation signals thereto. The baseband DSP subsystems
203 includes codec functions which are well-known in the art.
[0073] The base station controller interface 204 interfaces the
base transceiver station 4 to its controlling base station
controller 3a.
[0074] The controller 207 controls the operation of the base
transceiver station 4. It is coupled to the rf subsystem 202 for
supplying tuning instructions to the frequency synthesizer and to
the baseband DSP subsystem for supplying control data and
management data for transmission. The controller 207 operates
according to a program stored in the memory 210.
[0075] Referring to FIG. 4, each TDMA frame, used for communication
between the mobile stations 6a, 6b and the base transceiver
stations 4, comprises eight 0.577 ms time slots. A "26 multiframe"
comprises 26 frames and a "51 multiframe" comprises 51 frames.
Fifty one a "26 multiframes" or twenty six "51 multiframes" make up
one superframe. Finally, a hyperframe comprises 2048
superframes.
[0076] The data format within the time slots varies according to
the function of a time slot. A normal burst, i.e. time slot,
comprises three tail bits, followed by 58 encrypted data bits, a
26-bit training sequence, another sequence of 58 encrypted data
bits and a further three tail bits. A guard period of eight and a
quarter bit durations is provided at the end of the burst. A
frequency correction burst has the same tail bits and guard period.
However, its payload comprises a fixed 142 bit sequence. A
synchronization burst is similar to the normal burst except that
the encrypted data is reduced to two clocks of 39 bits and the
training sequence is replaced by a 64-bit synchronization sequence.
Finally, an access burst comprises eight initial tail bits,
followed by a 41-bit synchronization sequence, 36 bits of encrypted
data and three more tail bits. In this case, the guard period is
68.25 bits long.
[0077] When used for circuit-switched speech traffic, the
channelisation scheme is as employed in GSM.
[0078] Referring to FIG. 5, full rate packet switched channels make
use of 12 4-slot radio packets spread over a "51 multiframe". Idle
slots follow the third, sixth, ninth and twelfth radio packet.
[0079] Referring to FIG. 6, for half rate, packet switched
channels, both dedicated and shared, slots are allocated
alternately to two sub-channels.
[0080] The baseband DSP subsystems 103, 203 and controllers 107,
207 of the mobile stations 6a, 6b and the base transceiver stations
4 are configured to implement two protocol stacks. The first
protocol stack is for circuit switched traffic and is substantially
the same as employed in conventional GSM systems. The second
protocol stack is for packet switched traffic.
[0081] Referring to FIG. 7, the layers relevant to the radio link
between a mobile station 6a, 6b and a base station controller 4 are
the radio link control layer 401, the medium access control layer
402 and the physical layer 403.
[0082] The radio link control layer 401 has two modes: transparent
and non-transparent. In transparent mode, data is merely passed up
or down through the radio link control layer without
modification.
[0083] In non-transparent mode, the radio link control layer 401
provides link adaptation and constructs data blocks from data units
received from higher levels by segmenting or concatenating the data
units as necessary and performs the reciprocal process for data
being passed up the stack. It is also responsible for detecting
lost data blocks or reordering data block for upward transfer of
their contents, depending on whether acknowledged mode is being
used. This layer may also provide backward error correction in
acknowledged mode.
[0084] The medium access control layer 402 is responsible for
allocating data blocks from the radio link control layer 401 to
appropriate transport channels and passing received radio packets
from transport channels to the radio link control layer 403.
[0085] The physical layer 403 is responsible to creating
transmitted radio signals from the data passing through the
transport channels and passing received data up through the correct
transport channel to the medium access control layer 402.
[0086] Referring to FIG. 8, data produced for applications 404a,
404b, 404c propagates up the protocol stack from the medium access
control layer 402. The data from the applications 404a, 404b, 404c
can belong to any of a plurality of classes for which different
qualities of service are required. Data belonging to a plurality of
classes may be required by a single application. The medium access
control layer 402 directs data to the applications 404a, 404b, 404c
from different transport channels 405, 406, 407 according to class
to which it belongs.
[0087] Each receive transport channel 405, 406, 407 can be
configured to process received signals according to a plurality of
processing schemes 405a, 405b, 405c, 406a, 406b, 406c, 407a, 407b,
407c. The configuration of the transport channels 405, 406, 407 is
established during call setup on the basis of the capabilities of
the mobile station 6a, 6b and the network and the nature of the
application or applications 404a, 404b, 404c being run.
[0088] The processing schemes 405a, 405b, 405c, 406a, 406b, 406c,
407a, 407b, 407c are unique combinations of cyclic redundancy check
405a, 406a, 407a, channel decoding 405b, 406b, 407b and rate
matching 405c, 406c, 407c. These unique processing schemes are the
reciprocals of transmitter processing schemes which define
different "transport formats". An interleaving scheme may be
selected for each transport channel 405, 406, 407 and require
corresponding de-interleaving 405d, 406d, 407d. Thus, different
transport channels may use different interleaving schemes and, in
alternative embodiments, different interleaving schemes may be used
at different times by the same transport channel.
[0089] The combined data rate produced for the transport channels
405, 406, 407 must not exceed that of physical channel or channels
allocated to the mobile station 6a, 6b. This places a limit on the
transport format combinations that can be permitted For instance,
if there are three transport formats TF1, TF2, TF3 for each
transport channel, the following combinations might be valid: --
[0090] TF1 TF1 TF2 [0091] TF1 TF3 TF3 but not [0092] TF1 TF2 TF2
[0093] TF1 TF1 TF3
[0094] The received signal is de-interleaved 411 and then
demultiplexed by a demultiplexing process 410, which outputs
transport channel signals to respective transport channel
de-interleaving processes 405d, 406d, 407d.
[0095] A transport format combination indicator is spread across
one radio packet with portions placed in fixed positions in each
burst, on either side of the training symbols (FIG. 9) in this
example. The complete transport format combination indicator
therefore occurs at fixed intervals, i.e. the block length 20 ms.
This makes it possible to ensure transport format combination
indicator detection when different interleaving types are used e.g.
8 burst diagonal and 4 burst rectangular interleaving. Since the
transport format combination indicator is not subject to variable
interleaving, it can be readily located by the receiving station
and used to control processing of the received data.
[0096] The transport format combination indicator is extracted from
the received data stream by a transport format combination
indicator extraction process 414 after the deinterleaving process
411.
[0097] The transport format combination indicator from the
transport format combination indicator extraction process 414 is
decoded by a decoding process 413. The decoded transport format
combination indicator is then processed by a transport format
combination detecting process 412 which provides information on the
current transport format combination to the medium access control
layer 402. This information is then used in the medium access
control layer 402 to select the appropriate decoding and
de-interleaving process for the transport formats used in the
received signal.
[0098] FIG. 9 illustrates received signal quality determination in
the case where the received physical layer signal carries a data
stream comprising three transport channels using respective
formats. Of course, the data stream may comprise more or fewer
transport channels and the same transport format may be used by
more than one of the transport channels.
[0099] Referring to FIG. 9, first, second and third transport
channel quality determiners 501, 502, 503 receive the cyclic
redundancy check results from respective cyclic redundancy check
processes 405a, 406a, 407a and a bit error rate estimate from
respective channel decoding processes 405b, 406b, 407b.
[0100] The operation of the first transport channel quality
determiner 501 will now be described with reference to FIG. 10.
[0101] Referring to FIG. 10, at the start of a SACCH multiframe
period (also known as the SACCH reporting period), the CRC result
for a first transport block is received from the first cyclic
redundancy check process 405a (step s1). If the result is
determined to be true, i.e. the CRC is correct, (step s2), the BER
for the first transport block is obtained from the first channel
decoder 405b (step s3) and stored (step s4). A block counter is
then incremented (step s5). It is then determined whether the
current SACCH multiframe period has come to an end (step s6).
[0102] If the current SACCH multiframe period has not come to an
end (step s6), the program flow returns to step s1 where the CRC
for the next block is obtained.
[0103] If, at step s2, it is determined that the cyclic redundancy
check result is determined to be false, steps s3 to s5 are
skipped.
[0104] When all of the blocks of the current the current SACCH
multiframe period have been processed (step s6), the BER is
averaged over a period corresponding to the product of the block
period and the number of correctly received transport blocks, i.e.
the value accumulated by the step s5.
[0105] The second and third transport channel quality determiners
502, 503 operate in the same way as the first transport channel
quality determiners 501 except that the cyclic redundancy check
result and the BE R estimates are obtained from the corresponding
cyclic redundancy check process 406a, 407a and channel decoders
406b, 407b.
[0106] The transport channel quality determiners 501, 502, 503
output their average BERs and transport block counts to a physical
channel quality determiner 504.
[0107] The operation of the physical channel quality determiner 504
will now be described with reference to FIG. 11.
[0108] Referring to FIG. 11, the physical channel quality
determiner 504 obtains the TFCI applicable to the most recent
transport channel quality determinations (step s11) and then
receives the transport block counts from the transport channel
quality determiners 501, 502, 503 (step s12).
[0109] The TFCI information determines what percentage of each
radio packet is used by each transport channel. This information is
used to convert the transport block counts into the percentage of
the data in the transmitted data stream that was correctly received
in one SACCH multiframe, according to:
P = c = 1 n b ( c ) p ( c ) b T ( c ) ##EQU00001##
where c is the transport channel number, n is the number of
transport channels, b is the number of correctly received bits in
the transport block, b.sub.T is the number of bits in the transport
block in the transmitted signal and p is the percentage of the data
stream used by a particular transport channel.
[0110] If the result P is greater than or equal to 50%, the BERs
are obtained from the transport channel quality determiners 501,
502, 503 (step s15). The BERs are then averaged (step s16). In the
present embodiment, the BERs are averaged in accordance with the
following:
B = c = 1 n b ( c ) p ( c ) c = 1 n p ( c ) ##EQU00002##
where B is the average BER.
[0111] If, however, the percentage of the data in the transmitted
data stream that was incorrectly received is greater than 50% (step
s14), the average bit error rate B is set arbitrarily to 50%.
[0112] The average bit error rate B is then quantized and encoded
into 3 bits which are made available for transmission to a base
transceiver station 4 by the mobile station 6a in the SACCH as a
received signal quality report.
[0113] It will be appreciated that the formulae given above are
examples of the effect required and that the value ranges and
scaling factors actual used may vary.
[0114] A second embodiment of the present invention will now be
described.
[0115] A mobile station is as described above with the exception of
the generation of the received signal quality report. In this
embodiment, the report is based on the quality of the TFCI
signal.
[0116] Referring to FIG. 12, TFCI BERs are fed from the TFCI
decoder 413 (FIG. 8) to a received signal quality determiner 601.
The received signal quality determiner 601 generates a received
signal quality signal in dependence on the TFCI BERs from the TFCI
decoder 413 and outputs it for transmission in the SACCH.
[0117] Referring to FIG. 13, the received signal quality determiner
601 obtains a first TFCI BER for the first TFCI transmitted in a
SACCH multiframe period (step s31) and stores it (step s32).
Successive TFCI BERs are then obtained (step s31) and stored (step
s32) until the BER for the last TCFI of the current SACCH
multiframe period ends (step s33).
[0118] When the last BER has been obtained and stored, the stored
BERs are averaged (step s34) and then the average quantized and
encoded (step s35) and output (step s36) for transmission to a base
transceiver station 4 by the mobile station 6a in the SACCH as a
received signal quality report.
[0119] A third embodiment of the present invention will now be
described.
[0120] A mobile station is as described above with the exception of
the generation of the received signal quality report. In this
embodiment, the report is based on the quality of the received
training sequences.
[0121] As shown in FIG. 4, each burst comprises a training sequence
sandwiched between two blocks of data bits. The training sequences
are predetermined.
[0122] Referring to Referring to FIG. 14, received training
sequences are fed to a received signal quality determiner 701. The
received signal quality determiner 701 generates a received signal
quality signal in dependence on the received training sequences and
outputs it for transmission in the SACCH.
[0123] Referring to FIG. 12, TFCI BERs are fed from the TFCI
decoder 413 (FIG. 8) to a received signal quality determiner 601.
The received signal quality determiner 601 generates a received
signal quality signal in dependence on the TFCI BERs from the TFCI
decoder 413 and outputs it for transmission in the SACCH.
[0124] Referring to FIG. 15, the received signal quality determiner
701 obtains a first training sequence in a SACCH multiframe period
(step s41) and compares it with a reference copy (step s42). The
number of differences between the received training sequence and
the reference is added to a record of the errors for the current
SACCH multiframe period (step 43). The errors in successive
training sequences are then obtained (step s42) and added to the
error record (step s43) until the training sequence of the last
burst in the current SACCH multiframe period has been processed
(step s44).
[0125] When the last training sequence has been processed, the
accumulated error count is quantized (step s45) and output (step
s46) for transmission to a base transceiver station 4 by the mobile
station 6a in the SACCH as a received signal quality report.
[0126] The three embodiments described above may be combined to
produce additional embodiments. For instance, bit error rates
obtained by two or three techniques may be averaged to produce a
bit error rate that is then quantized, encoded and transmitted to a
base transceiver station 4 by the mobile station 6a in the SACCH as
a received signal quality report.
[0127] It is to be understood that the foregoing embodiments are
merely examples and that many modifications are possible without
departing from the spirit and scope of the appended claims.
* * * * *