Methods and systems for allocation of macro cell resources in a distributed femto cell network and a distributed relay station network
View Patent ↗Methods and systems for reusing macro cell resources in femto cell base stations or relay stations in a non-collaborative manner are disclosed. In addition, orthogonal resource allocation between a macro cell base station and femto cell base stations/relay stations may be dynamically adjusted by considering user-population variance. Moreover, an additional level of spatial reuse by femto cell base stations or relay stations can be provided by employing macro cell user location information.
1. A method for uncoordinated allocation of tiles corresponding to time-frequency resource blocks of orthogonal frequency division multiple access (OFDMA) frames between distributed extension cell base stations, said method being performed at a given extension cell base station and comprising:
selecting a prime number (P) based on a total number (N) of extension cell base stations contending for said tiles;
generating a hash function by randomly choosing a hash vector with components selected from a hash table of size P, and dividing said tiles into sets of P tiles each;
allocating tiles from said sets of P tiles to the given extension cell base station by applying the hash function to each set; and
assigning said allocated tiles to clients of the given extension cell and transmitting assignment messages to said clients to permit communication on said allocated tiles.
2. The method of claim 1 , wherein said generating further comprises representing an identifier of said given extension cell in binary form, splitting the
identifier in binary form into r components of an identifier vector, wherein r is
⌈
log
2
N
⌊
log
2
P
⌋
⌉
,
and performing modulo-P addition on the dot product of the hash vector and the identifier vector.
3. The method of claim 1 , wherein said steps of claim 1 are performed during an initialization time frame and wherein said method further comprises performance of the following steps during subsequent time frames:
determining which tiles of said allocated tiles collide with signals transmitted by other extension cell base stations;
generating a second hash function by randomly choosing a second hash vector with components selected from a hash table of size two;
reallocating tiles from the colliding tiles to the given extension cell base station by applying the second hash function to each of the colliding tiles; and
assigning said reallocated tiles to the clients of the given extension cell and transmitting assignment messages to said clients to permit communication on said reallocated tiles.
4. The method of claim 3 , wherein said generating a second hash function further comprises:
splitting the identifier in binary form into R components of a second identifier vector, where R is ┌log 2 N┐, and performing modulo-2 addition on the dot product of the second hash vector and the second identifier vector.
5. The method of claim 3 , wherein said reallocating comprises retaining allocated tiles that do not collide with signals transmitted by other extension cell base stations for use by the given extension cell base station and wherein said assigning said reallocated tiles comprises assigning said reallocated tiles and said retained tiles to the clients of the given extension cell and transmitting assignment messages to said clients to permit communication on said reallocated tiles and said retained tiles.
6. The method of claim 5 , wherein said steps of claim 3 are iterated until all tiles assigned by the extension cell base station do not collide with signals transmitted by other extension cell base stations.
7. The method of claim 1 , wherein said steps of claim 1 are performed during an initialization time frame and wherein said method further comprises performance of the following steps during subsequent time frames:
from a preceding time frame, compiling a group of tiles (S) composed of allocated tiles that are idle tiles and allocated tiles that collide with signals transmitted by other extension cell base stations;
for each set of said sets of P tiles that includes tiles within S:
determining the number (m) of allocated tiles within S that are within the corresponding set,
generating a second hash function by randomly choosing a second hash vector with components selected from a hash table of size q, wherein q is a lowest prime number (q) that is greater than or equal to m, and
reallocating tiles from S to the given extension cell base station by applying the second hash function to the corresponding set; and
assigning said reallocated tiles to the clients of the given extension cell and transmitting assignment messages to said clients to permit communication on said reallocated tiles.
8. The method of claim 7 , wherein said generating a second hash function further comprises:
splitting the identifier in binary form into R components of a second identifier vector, where R is
⌈
log
2
N
⌊
log
2
q
⌋
⌉
,
and performing modulo-q addition on the dot product of the second hash vector and the second identifier vector.
9. The method of claim 7 , wherein said reallocating comprises retaining allocated tiles that do not collide with signals transmitted by other extension cell base stations and are not idle for use by the given extension cell base station and wherein said assigning said reallocated tiles comprises assigning said reallocated tiles and said retained tiles to the clients of the given extension cell and transmitting assignment messages to said clients to permit communication on said reallocated tiles and said retained tiles.
10. The method of claim 9 , wherein said steps of claim 7 are iterated until all tiles assigned by the extension cell base station do not collide with signals transmitted by other extension cell base stations.