Method and apparatus for searching for modes and frequencies

• US 8,467,787 B2
• Filed: 05/13/2010
• Issued: 06/18/2013
• Est. Priority Date: 12/27/2007
• Status: Expired due to Fees

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Wu, Gengshi
• Primary Examiner(s): Wendell, Andrew
• Assistant Examiner(s): Tran, Paul P
• Application Number:
  US12/779,712
• Publication Number:
  US 20100222056A1
• Time in Patent Office: 1,132 Days
• Field of Search: 455/67.11, 455/127.4, 455/160.1, 455/161.2, 455/161.3, 455/182.1, 455/303, 455/434, 455/432.1, 455/435.1, 455/435.2, 455/435.3, 455/437, 455/447, 455/450, 455/452.1, 455/502, 455/512, 455/513, 455/515, 455/69, 455/226.1, 455/422.1, 455/552.1, 370/328, 370/329, 370331-332, 370/335, 370/336, 370/338, 370/341, 370/342, 370/343, 370/348, 370/337, 375/145, 375/344, 375/147, 375/346, 375/350
• US Class Current: 455/434
• CPC Class Codes: H04B 1/0053 with common antenna for more than one band
• CPC Class Codes: H04B 1/70758 Multimode search, i.e. using multiple search strategies
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04B 1/7087 Carrier synchronisation aspects
• CPC Class Codes: H04J 11/0083 Multi-mode cell search, i.e. where several modes or systems can be used, e.g. backwards compatible, dual mode or flexible systems
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

The present invention discloses a method and an apparatus for searching for modes and frequencies. The method includes: obtaining signal energy of all frequency grids within a frequency range; obtaining energy of each mode on a smallest bandwidth according to the signal energy of the grids; sorting the energy on the smallest bandwidths of all modes; and accessing a specified number of frequencies and modes of the highest energy in the sorting result. With the present invention, energy on the smallest bandwidths of all modes at a frequency band is obtained and sorted and then an access mode is determined according to the sorting result. Thus the access mode to use for a specified frequency can be quickly determined so as to improve the access success rate of a terminal in the subsequent access process.

Claims

1. A method for searching for modes and frequencies by a User Equipment (UE), the method comprising:

obtaining, by the UE, signal energy of all frequency grids within a frequency range;

obtaining for each mode, using the obtained signal energy of all frequency grids, the signal energy in each of a plurality of smallest bandwidths within the mode over the frequency range;

sorting the energy on the smallest bandwidths of all modes;

accessing a specified number of frequencies and modes of highest energy in the sorting result; and

wherein obtaining the signal energy in each of a plurality of smallest bandwidths within the mode over the frequency range comprises;

opening a window according to the smallest bandwidth of a selected mode, wherein the number of the frequency grids included in the window is equal to the number of the frequency grids of the smallest bandwidth of the selected mode,

sliding over the frequency range the smallest bandwidth window by one frequency grid in each slide and obtaining a sum of signal energy of frequency grids in the smallest bandwidth window in each slide as the energy on each smallest bandwidth of the mode, and

marking the energy on each smallest bandwidth of the mode according to the amount of energy.

2. The method of claim 1, wherein after obtaining the signal energy of all frequency grids within the frequency range, the method further comprises:

correcting the obtained signal energy of all grids.

3. The method of claim 2, wherein correcting the obtained signal energy of all grids comprises:

obtaining a grid of highest energy within the frequency range and marking the grid as correction not required;

deducting a first adjacent frequency attenuation of the highest energy from the energy of the first adjacent frequency of the grid of the highest energy and deducting a second adjacent frequency attenuation of the highest energy from the energy of the second adjacent frequency of the grid of the highest energy; and

obtaining a grid of highest energy except the grid marked as correction not required and repeating the correction process until all grids are marked as correction not required.

4. The method of claim 3, wherein accessing the specified number of frequencies and modes of the highest energy in the sorting result comprises:

performing synchronization, cell detection, and reception of cell broadcast on each of the specified number of frequencies and modes of the highest energy;

receiving mode and frequency information via cell broadcast and ending the search if cell broadcast is received and camping on a cell is successful;

if cell broadcast is not received and camping on a cell is unsuccessful, proceeding to search in a next possible frequency band until an available mode and frequency are found.

5. The method of claim 1, further comprising:

judging the mode of the strong frequency when a strong frequency of another mode exists on a smallest bandwidth of one mode.

6. The method of claim 5, wherein judging the mode of the strong frequency comprises:

a possible first mode, whose smallest bandwidth is f₁ and whose signal energy is E₁;

a possible second mode, whose smallest bandwidth is f₂ and whose signal energy is E₂;

judging whether E₁>

T*E₂/(f₂/f₁) is satisfied, where T is a predetermined threshold; and

determining that the strong frequency belongs to the first mode if the inequation is satisfied;

determining that the strong frequency belongs to the second mode if the inequation is not satisfied.

7. The method of claim 1, wherein accessing the specified number of frequencies and modes of the highest energy in the sorting result comprises:

performing synchronization, cell detection, and reception of cell broadcast on each of the specified number of frequencies and modes of the highest energy;

receiving mode and frequency information via cell broadcast and ending the search if cell broadcast is received and camping on a cell is successful;

if cell broadcast is not received and camping on a cell is unsuccessful, proceeding to search in a next possible frequency band until an available mode and frequency are found.

8. An apparatus for searching for modes and frequencies, the apparatus comprising:

a grid energy obtaining unit, adapted to obtain signal energy of all frequency grids within a frequency range;

a mode energy obtaining unit, adapted to obtain for each mode, using the obtained signal energy of all frequency grids, the signal energy in each of a plurality of smallest bandwidths within the mode over the frequency range;

a sorting unit, adapted to sort the energy on the smallest bandwidths of all modes obtained by the mode energy obtaining unit;

an accessing unit, adapted to access a specified number of frequencies and modes of highest energy in the sorting result of the sorting unit; and

wherein the mode energy obtaining unit comprises;

a window opening open a window according to the smallest bandwidth of a selected mode, wherein the number of the frequency grids included in the window is equal to the number of the frequency grids of the smallest bandwidth of the selected mode,

a window sliding subunit, adapted to slide over the frequency range the smallest bandwidth window opened by the window opening subunit by one frequency grid in each slide,

an energy recording subunit, adapted to obtain a sum of signal energy of frequency grids in the smallest bandwidth window in each slide of the window sliding subunit, that is, to obtain energy on every smallest bandwidth of the mode at the frequency band, and

an energy marking subunit, adapted to mark the energy on every smallest bandwidth of the mode recorded by the energy recording subunit according to the amount of energy.

9. The apparatus of claim 8, further comprising:

a grid energy correcting unit, adapted to correct the signal energy of all grids obtained by the grid energy obtaining unit and send the corrected signal energy of the grids to the mode energy obtaining unit.

10. The apparatus of claim 9, wherein the grid energy obtaining unit comprises:

a grid obtaining subunit, adapted to obtain a grid of highest signal energy in the frequency range;

a marking subunit, adapted to mark the grid obtained by the grid obtaining unit as correction not required;

a correcting subunit, adapted to deduct a first adjacent frequency attenuation of the highest energy from the energy of the first adjacent frequency of the grid of the highest energy and deduct a second adjacent frequency attenuation of the highest energy from the energy of the second adjacent frequency of the grid of the highest energy; and

a cycling subunit, adapted to control the grid obtaining subunit to obtain a grid of the highest energy except the grid marked as correction not required after the correcting subunit completes correcting the grid of the highest energy, and the correcting subunit to repeat the energy correction process until all grids are marked as correction not required.

11. The apparatus of claim 8, further comprising:

a mode judging subunit, adapted to judge the mode of the strong frequency when a strong frequency of another mode is found on a smallest bandwidth of one mode.

12. The apparatus of claim 11, wherein:

the mode judging subunit may be a first judging unit, adapted to judge whether E₁>

T*E₂/(f₂/f₁) is satisfied and if the inequation is satisfied, determine that the strong frequency belongs to a first mode, and if the inequation is not satisfied, determine that the strong frequency belongs to a second mode, where f₁ is the smallest bandwidth of the possible first mode, E₁ is the signal energy of the possible first mode, f₂ is the smallest bandwidth of the possible second mode, E₂ is the signal energy of the possible second mode, and T is a predetermined threshold.

13. The apparatus of claim 8, wherein the accessing unit comprises:

a synchronizing subunit, adapted to perform synchronization, cell detection, and reception of cell broadcast on each of the specified number of frequencies and modes of highest energy;

a judging subunit, adapted to determine that the synchronization is successful and that the search is complete after broadcast is received from a cell synchronized by the synchronizing subunit and camping on the cell is successful, and notify the synchronizing subunit to search in a next possible frequency band if broadcast is not received from a cell synchronized by the synchronizing subunit or camping on the cell is unsuccessful; and

a receiving subunit, adapted to receive mode and frequency information via cell broadcast after the judging subunit determines that the synchronization is successful.