Shrink a large table (other options)

I would like to know the opinion from experienced Oracle DBAs on shrinking a fairly large table.

Database: Oracle 11gR2, OLTP

We have a fairly large table (75 Gig) that frequently undergoes with lots of deletes. I tried to shrink the table several times to release the space and improve performance, and I received UNDO segment error every time. The expected amount of space release is 25%.

ORA-30036: unable to extend segment by 8 in undo tablespace 'UNDOTBS'

Our UNDO tablespace size is 32 Gig. Here are the commands I used.

alter table <table name> enable row movement; alter table <table name> shrink space;

I would like to know what are my other options.

Thanks
Bheem Aitha

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