SCRAMBLING CODE PLANNING DEVICE AND METHOD FOR USING SAME IN WIRELESS COMMUNICATION NETWORK

• US 20130039281A1
• Filed: 08/08/2011
• Published: 02/14/2013
• Est. Priority Date: 08/08/2011
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Sen, Ayan, Sarkar, Debasish
• Granted Patent: US 8,717,887 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]

Abstract

A scrambling code planning device and method are described herein for allocating primary scrambling codes to sites (e.g., Node B'"'"'s sites) within a wireless communication network. In addition, a wireless communication network is described herein that includes the scrambling code planning device which allocates the primary scrambling codes to the sites (e.g., Node B'"'"'s sites).

Claims

1. A scrambling code planning device for allocating a plurality of primary scrambling codes to sites within a wireless communication network, the scrambling code planning device comprising:

a processor; and

a memory that stores processor-executable instructions therein where the processor interfaces with the memory and executes the processor-executable instructions to enable the following;

forming a plurality of clusters, wherein each cluster includes one or more of the sites of the wireless communications network, and wherein each cluster will not include more than a first predetermined number of sites;

allocating one of a plurality of primary scrambling code sets to each of the formed clusters, wherein there are a predetermined number of primary scrambling code sets and each primary scrambling code set includes a predetermined number of the primary scrambling codes; and

allocating to the sites in each of the formed clusters which have the same primary scrambling code set allocated thereto the predetermined number of the primary scrambling codes associated with the same primary scrambling code set.

2. The scrambling code planning device of claim 1, wherein there are eight primary scrambling code sets and each primary scrambling code set includes sixty four primary scrambling codes.

3. The scrambling code planning device of claim 1, wherein during the first allocating operation one of the plurality of primary scrambling code sets is reserved and not allocated to the formed clusters.

4. The scrambling code planning device of claim 1, wherein the processor further executes the processor-executable instructions in the memory to perform the forming operation by:

initially forming the plurality of clusters by placing a second predetermined number of sites into each cluster, wherein the first predetermined number of sites is larger than the second predetermined number of sites;

absorbing any non-placed sites into one or more of the initially formed clusters taking into account proximity of the non-placed sites with respect to the initially formed clusters while ensuring each of the initially formed clusters which absorb the non-placed sites do not include more than the first predetermined number of sites; and

if there still remains non-placed sites after the absorbing step, then forming a new cluster in which the remaining non-placed sites are placed so long as the new cluster does not include more than the first predetermined number of sites.

5. The scrambling code planning device of claim 4, wherein the first predetermined number of sites is twenty one sites and the second predetermined number of sites is seventeen sites.

6. The scrambling code planning device of claim 1, wherein the processor further executes the processor-executable instructions in the memory to perform the first allocating operation by:

creating a neighboring table which identifies neighboring clusters associated with each of a plurality of source clusters, where the source clusters and the neighboring clusters make-up the formed clusters; and

allocating one of the primary scrambling code sets to each of the source clusters so as not to use anyone of the primary scrambling code sets that was allocated to the associated neighboring clusters.

7. The scrambling code planning device of claim 1, wherein the processor further executes the processor-executable instructions in the memory to perform the second allocating operation by:

identifying the formed clusters that have been allocated the same primary scrambling code set; and

assigning the predetermined number of primary scrambling codes associated with the same primary scrambling code set to the sites in the identified formed clusters in a manner that maintains a maximum tier separation when reusing the same primary scrambling codes.

8. The scrambling code planning device of claim 7, wherein the processor further executes the processor-executable instructions in the memory to perform the assigning operation by:

maintaining at least a predetermined number of tier separation when reusing the same primary scrambling codes in the identified formed clusters and if not possible then maintain a lower predetermined number of tier separation when reusing the same primary scrambling codes in the identified formed clusters and if this is not possible and a single tier separation is not possible without reusing the same primary scrambling codes in the identified formed clusters then the primary scrambling codes are shuffled between the identified formed clusters in an attempt to create at least one tier separation between successive co-primary scrambling codes allocations and if this is not possible then use the primary scrambling codes from a reserved primary scrambling code set.

9. A method for allocating a plurality of primary scrambling codes to sites within a wireless communication network, the method implemented by a scrambling code planning device comprising the steps of:

forming a plurality of clusters, wherein each cluster includes one or more of the sites of the wireless communications network, and wherein each cluster will not include more than a first predetermined number of sites;

allocating one of a plurality of primary scrambling code sets to each of the formed clusters, wherein there are a predetermined number of primary scrambling code sets and each primary scrambling code set includes a predetermined number of the primary scrambling codes; and

allocating to the sites in each of the formed clusters which have the same primary scrambling code set allocated thereto the predetermined number of the primary scrambling codes associated with the same primary scrambling code set.

10. The method of claim 9, wherein there are eight primary scrambling code sets and each primary scrambling code set includes sixty four primary scrambling codes.

11. The method of claim 9, wherein during the first allocating step one of the plurality of primary scrambling code sets is reserved and not allocated to the formed clusters.

12. The method of claim 9, wherein the forming step further comprises the steps of:

initially forming the plurality of clusters by placing a second predetermined number of sites into each cluster, wherein the first predetermined number of sites is larger than the second predetermined number of sites;

absorbing any non-placed sites into one or more of the initially formed clusters taking into account proximity of the non-placed sites with respect to the initially formed clusters while ensuring each of the initially formed clusters which absorb the non-placed sites do not include more than the first predetermined number of sites; and

if there still remains non-placed sites after the absorbing step, then forming a new cluster in which the remaining non-placed sites are placed so long as the new cluster does not include more than the first predetermined number of sites.

13. The method of claim 12, wherein the first predetermined number of sites is twenty one sites and the second predetermined number of sites is seventeen sites.

14. The method of claim 9, wherein the first allocating step further comprises the steps of:

creating a neighboring table which identifies neighboring clusters associated with each of a plurality of source clusters, where the source clusters and the neighboring clusters make-up the formed clusters; and

allocating one of the primary scrambling code sets to each of the source clusters so as not to use anyone of the primary scrambling code sets that was allocated to the associated neighboring clusters.

15. The method of claim 9, wherein the second allocating step further comprises the steps of:

identifying the formed clusters that have been allocated the same primary scrambling code set; and

assigning the predetermined number of primary scrambling codes associated with the same primary scrambling code set to the sites in the identified formed clusters in a manner that maintains a maximum tier separation when reusing the same primary scrambling codes.

16. The method of claim 15, wherein the assigning step further comprises the steps of:

maintaining at least a predetermined number of tier separation when reusing the same primary scrambling codes in the identified formed clusters and if not possible then maintain a lower predetermined number of tier separation when reusing the same primary scrambling codes in the identified formed clusters and if this is not possible and a single tier separation is not possible without reusing the same primary scrambling codes in the identified formed clusters then the primary scrambling codes are shuffled between the identified formed clusters in an attempt to create at least one tier separation between successive co-primary scrambling codes allocations and if this is not possible then use the primary scrambling codes from a reserved primary scrambling code set.

17. A wireless communication network comprising:

an operational support system;

a plurality of nodes each of which manages a site;

a controller coupled to the operational support system and configured to manage the plurality of nodes;

a scrambling code planning device coupled to the operational support system and configured to allocate a plurality of primary scrambling codes to the sites, wherein the scrambling code planning includes a primary scrambling code generation unit which;

forms a plurality of clusters, wherein each cluster includes one or more of the sites, and wherein each cluster will not include more than a first predetermined number of sites;

allocates one of a plurality of primary scrambling code sets to each of the formed clusters, wherein there are a predetermined number of primary scrambling code sets and each primary scrambling code set includes a predetermined number of the primary scrambling codes; and

allocates to the sites in each of the formed clusters which have the same primary scrambling code set allocated thereto the predetermined number of the primary scrambling codes associated with the same primary scrambling code set.

18. The wireless communication network of claim 17, wherein the scrambling code planning device further includes a primary scrambling code reuse check unit that interacts with the operational support system to fetch an existing primary scrambling code plan and then prepares a primary scrambling code reuse summary by calculating a reuse factor for any given primary scrambling code as well as the distance and tier corresponding to each reuse of the given primary scrambling code.

19. The wireless communication network of claim 17, wherein the scrambling code planning device further includes a primary scrambling code conflict analyzer that uses an existing primary scrambling code plan to compute tier 1 and tier 2 primary scrambling code conflicts.

20. The wireless communication network of claim 17, wherein the scrambling code planning device further includes a handover matrix based primary scrambling code replan unit that creates a primary scrambling code plan by correlating tier two conflicts and handover matrix data.