Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W56/00—Synchronisation arrangements
  • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
  • H04W56/0045—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by altering transmission time
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2662—Arrangements for Wireless System Synchronisation
  • H04B7/2671—Arrangements for Wireless Time-Division Multiple Access [TDMA] System Synchronisation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W24/00—Supervisory, monitoring or testing arrangements
  • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements

Definitions

• CD 0- 0 pi iQ ⁇ rt P- PJ P- 0 0 ⁇ 0 pj: C ⁇ 0 ⁇ ⁇ ⁇ P ) 0 C ⁇ ⁇ p P> rf 1 0 J ⁇ 0 ⁇ 0 P. rt P- N P. 0 3 p- 1 ⁇
• the invention is based on the insight that, although the tatsumble ⁇ Liche synchronism error between two base stations in the individual case a specific handover can not be specified, but that it is generally possible to specify the accuracy of the Synchronitat the two base stations, that is, an upper limit for estimate the amount of the synchronism error, which it will not exceed with a predetermined probability.
• Time difference between the time standards of the two base stations determined timing advance value i.e. a delay in transmission by the subscriber station, depending on the known accuracy of the synchronicity, is achieved that the radio signal of the terminal device transmitted with reduced timing advance may be at the second base station does not arrive immediately at the beginning of the allocated time slot, but in no case before the beginning of the time slot.
• reaching the radio signal into the guard period following the time slot can be tolerated.
• the reduction in the timing advance value is preferably twice the accuracy of the synchronicity specified in time units.
• the accuracy of the synchronicity is too poor, a reduction in the timing advance value corrected on the basis of the measured time shift could result in essential parts of the radio signal falling into the guard period or even into the subsequent time slot of another station on the base station. In such a case, it is more appropriate to completely refrain from correcting the timing advance value and to use a timing advance value of 0 for transmission to the second base station. In this case, a new measurement of the timing advance by the second base station is essential.
• the accuracy of the synchronicity of the two base stations involved in the handover is preferably signaled to the terminal in the course of the handover process.
• heuristic estimates of the accuracy of the synchronicity are also conceivable. For example, Assume that the accuracy of the synchronicity is proportional to the distance between two base stations. The distance to the first base station is known to the terminal from its timing advance used before the handover. If one assumes that the distance to the second base station will be of the same order of magnitude as that to the first, the terminal can derive an estimate of the accuracy of the synchronicity directly from the timing advance value.
• the pairs of base stations of the radio communication system are classified into one of several classes depending on the accuracy of their synchronicity, and the terminal is signaled in each case to the class to which the pair of stations belongs between which the Handover takes place.
• the signaling of the accuracy of the synchronicity can be limited to the transmission of a small number of bits. If the terminal takes the upper limit of such a class as the value for the accuracy of the synchronicity, a premature arrival of the signal at the base station is reliably avoided, regardless of the actual value of the accuracy.
• the number of classes is preferably at least three. These classes preferably include one where the accuracy the synchronicity is so good that a reduction in the timing advance value corrected on the basis of the measured time shift can be completely dispensed with. Such a class expediently comprises pairs of stations at which the accuracy of the synchronicity does not exceed a limit in the range 100-500 ns.
• a further division of the classes expediently distinguishes those pairs of stations where a reduction in the timing advance value by a value derived from the accuracy of the synchronicity makes sense from those pairs where the accuracy of the synchronicity is so bad that a complete redefinition timing advance by the second base station is more advantageous.
• the limit for this subdivision is expediently between 500 ns and 2.5 ⁇ s in the calculation.
• FIG. 1 is a schematic block diagram of a radio communication system in which the present invention is applicable;
• FIG. 2 shows a time diagram to explain the determination of the timing advance value by a terminal in the event of a handover
• dl the path length between the base station BS1 and the terminal MS.
• This delay dl / c is also the value of the timing ad vance ⁇ TA1, which the terminal MS is used for transmitting to the base station BSl.
• the subscriber station MS uses a local time scale for the time control of its tasks before the handover, which is based on the time standard transmitted by the base station BS1. You can see the time of arrival
• the distance .DELTA.t between the arrival times of the two time standards denotes the amount by which the terminal MS must correct its timing advance value in order to be able to communicate correctly with the base station BS: the terminal MS 00 oo ro ro P> P 1
• TA2 TAl + ⁇ t-2Gsync
• the timing advance value is thus 3Gsync smaller than in the case of FIG. 2;
• the reception window for the signal of the terminal MS at the base station BS2 is premature by Gsync, so that the signal of the terminal MS arrives at the base station BS2 with a delay of 4Gsync against its reception window in the time interval F a .
• the timing advance value is therefore smaller by Gsync than with perfect synchronization.
• the reception window of the base station BS2 is also delayed by Gsync compared to that of the base station BS1, so that the signal of the terminal MS at the base station BS2 coincides exactly with the reception window F d assigned to it.
• the risk that the signal of the terminal MS at the Basissta ⁇ tion BS2 arrives too early to be evaluated to correct, is thus eliminated regardless of the amount and direction of the actual synchronization error Esync.
• the handover between two base stations does not necessarily signal the accuracy of the synchronicity to the terminal that has been determined for the two base stations, but rather only an indication of the affiliation of the relevant pair of base stations to one transferred from several accuracy classes.
• the number of bits required for signaling the accuracy is reduced to the two-logarithm of the number of classes.
• a second class comprises pairs of base stations with an average accuracy of the synchronicity Gsync of typically ⁇ 500 ns. With such a value of Gsync, taking it into account when determining TA2 in the worst case can lead to a delayed arrival of the signal at the base station BS2 by 2 ⁇ s.
• a third accuracy class contains those pairs of base stations already mentioned above in which the accuracy of the synchronicity is so poor that taking them into account when determining TA2 can lead to unusually large delays in the signal at the base station BS2.
• the terminal MS uses the upper accuracy limit of this class as Gsync to determine TA2.
• all pairs of base stations with Gsync ⁇ 200 ns can enter the first Class, those with 200 ns ⁇ Gsync ⁇ 1 ⁇ s in the second and all with Gsync> 1 ⁇ s in the third class.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Time-Division Multiplex Systems (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2000
  • 2000-08-16 DE DE10039967A patent/DE10039967B4/de not_active Expired - Fee Related
• 2001
  • 2001-08-10 WO PCT/DE2001/003079 patent/WO2002015624A1/de not_active Application Discontinuation
  • 2001-08-10 US US10/344,675 patent/US20040128095A1/en not_active Abandoned
  • 2001-08-10 EP EP01964898A patent/EP1310133A1/de not_active Withdrawn
  • 2001-08-10 CA CA002419615A patent/CA2419615A1/en not_active Abandoned
  • 2001-08-10 JP JP2002519362A patent/JP2004506392A/ja not_active Withdrawn
  • 2001-08-10 CN CNA018173071A patent/CN1470146A/zh active Pending

Non-Patent Citations (1)

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